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276 views297 pages

UM10120

I2C chapter: multiple errors corrected (Chapter 13) IAP call example updated (Section 20. On page 257) Numerous editorial updated throughout the user manual.

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UM10120

LPC2131/2/4/6/8 User manual

Rev. 3 — 4 October 2010 User manual

Document information
Info Content
Keywords LPC2131, LPC2132, LPC2134, LPC2136, LPC2138, LPC2131/01,
LPC2132/01, LPC2134/01, LPC2136/01, LPC2138/01, LPC2000,
LPC213x, LPC213x/01, ARM, ARM7, embedded, 32-bit, microcontroller
Abstract LPC213x and LPC213x/01 User manual
NXP Semiconductors UM10120
LPC213x and LPC213x/01 UM

Revision history
Rev Date Description
v3 20101004 Modifications:
• New document template applied.
• I2C chapter: multiple errors corrected (Chapter 13).
• IAP call example updated (Section 20.9 on page 257).
• WDFEED register description updated (Section 16.4.3 “Watchdog Feed register
(WDFEED - 0xE000 0008)”).
• RTC usage note updated (Section 17.5 “RTC usage notes”).
• CTCR register bit description corrected (Section 17.4.4 “Clock Tick Counter Register
(CTCR - 0xE002 4004)”).
• PINSEL2 register description updated (Section 6.4.3 “Pin function Select register 2
(PINSEL2 - 0xE002 C014)”).
• PWM TCR register bit 3 description updated (Section 15.4.2 “PWM Timer Control
Register (PWMTCR - 0xE001 4004)”).
• U0IER register bit description corrected (Section 9.3.6 “UART0 Interrupt Enable
Register (U0IER - 0xE000 C004, when DLAB = 0)”).
• U1IER register bit description corrected (Section 10.3.6 “UART1 Interrupt Enable
Register (U1IER - 0xE001 0004, when DLAB = 0)”).
• Pin description updated for VBAT, VREF, and RTCX1/2 (Table 35 “Pin description”).
• SSP CR0 register corrected (Section 12.4.1 “SSP Control Register 0 (SSPCR0 -
0xE006 8000)”).
• ADC maximum voltage updated (Table 213 “ADC pin description”).
• Minimum DLL value for use with fractional divider corrected (Section 9.3.4 “UART0
Fractional Divider Register (U0FDR - 0xE000 C028)” and Section 10.3.4 “UART1
Fractional Divider Register (U1FDR - 0xE001 0028)”).
• CRP levels updated (Section 20.7 “Code Read Protection (CRP)”).
• Numerous editorial updated throughout the user manual.
02 20060918 Updated edition of the User Manual covering both LPC213x and LPC213x/01 devices. For
detailed list of enhancements introduced by LPC213x/01 see Section 1.2 “Enhancements
introduced with LPC213x/01 devices” on page 3.
Other changes applied to Rev 01:
• ECC information in Section 20.6 “Flash content protection mechanism” corrected
• The SSEL signal description corrected for CPHA = 0 and CPHA = 1 (Section 11.2.2
“SPI data transfers”)
• Bit SPIE description corrected in Section 11.4.1 “SPI Control Register (S0SPCR -
0xE002 0000)”
• Details on VBAT setup added in Section 17.5 “RTC usage notes”
01 20050624 Initial version

Contact information
For more information, please visit: http://www.nxp.com
For sales office addresses, please send an email to: salesaddresses@nxp.com
UM10120 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved.

User manual Rev. 3 — 4 October 2010 2 of 297

UM10120
Chapter 1: Introductory information
Rev. 3 — 4 October 2010 User manual

1.1 Introduction
The LPC213x and LPC213x/01 microcontrollers are based on a 16/32 bit ARM7TDMI-S
CPU with real-time emulation and embedded trace support that combines the
microcontroller with embedded high speed Flash memory ranging from 32 kB to 512 kB. A
128-bit wide memory interface and a unique accelerator architecture enable 32-bit code
execution at maximum clock rate. For critical code size applications, the alternative 16-bit
Thumb Mode reduces code by more than 30 % with minimal performance penalty.

Due to their tiny size and low power consumption, these microcontrollers are ideal for
applications where miniaturization is a key requirement, such as access control and
point-of-sale. With a wide range of serial communications interfaces and on-chip SRAM
options of 8/16/32 kB, they are very well suited for communication gateways and protocol
converters, soft modems, voice recognition and low end imaging, providing both large
buffer size and high processing power. Various 32-bit timers, single or dual 10-bit
8 channel ADC(s), 10-bit DAC, PWM channels and 47 fast GPIO lines with up to nine
edge or level sensitive external interrupt pins make these microcontrollers particularly
suitable for industrial control and medical systems.

Important: The term “LPC213x“ in the following text will be used both for devices with and
without /01 suffix. Only when needed “LPC213x/01” will be used to identify the latest ones:
LPC2131/01, LPC2132/01, LPC2134/01, LPC2136/01, and/or LPC2138/01.

1.2 Enhancements introduced with LPC213x/01 devices

• Fast GPIO ports enable pin toggling up to 3.5x faster than the original LPC213x. Also,
Enhanced parallel ports allow for a port pin to be read at any time regardless of the
function selected on it. For details see GPIO chapter on page 79.
• Dedicated result registers for AD converter(s) reduce interrupt overhead. For details
see ADC chapter on page 231.
• UART0/1 include Fractional Baudrate Generator, auto-bauding capabilities and
handshake control fully implemented in hardware. For more details see UART0
chapter on page 93 and UART1 chapter on page 109.
• Enhanced BOD control enables further reduction of power consumption. For details
see Table 30 “Power Control register (PCON - address 0xE01F C0C0) bit description”
on page 41

1.3 Features
• 16/32-bit ARM7TDMI-S microcontroller in a tiny LQFP64 package
• 8/16/32 kB of on-chip static RAM and 32/64/128/256/512 kB of on-chip Flash program
memory. 128 bit wide interface/accelerator enables high speed 60 MHz operation.
• In-System/In-Application Programming (ISP/IAP) via on-chip boot-loader software.
Single Flash sector or full chip erase in 400 ms and 256 bytes programming in 1 ms.

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• EmbeddedICE and Embedded Trace interfaces offer real-time debugging with the
on-chip RealMonitor software and high speed tracing of instruction execution.
• One (LPC2131/2) or two (LPC2134/6/8) 8 channel 10-bit A/D converters provide a
total of up to 16 analog inputs, with conversion times as low as 2.44 μs per channel.
• Single 10-bit D/A converter provides variable analog output. (LPC2132/4/6/8 only).
• Two 32-bit timers/external event counters (with four capture and four compare
channels each), PWM unit (six outputs) and watchdog.
• Low power Real-time clock with independent power and dedicated 32 kHz clock input.
• Multiple serial interfaces including two UARTs (16C550), two Fast I2C (400 kbit/s), SPI
and SSP with buffering and variable data length capabilities.
• Vectored interrupt controller with configurable priorities and vector addresses.
• Up to 47 of 5 V tolerant general purpose I/O pins in a tiny LQFP64 package.
• Up to nine edge or level sensitive external interrupt pins available.
• 60 MHz maximum CPU clock available from programmable on-chip Phase-Locked
Loop (PLL) with settling time of 100 μs.
• On-chip integrated oscillator operates with external crystal from 1 MHz to 25 MHz.
• Power saving modes include Idle and Power-down.
• Individual enable/disable of peripheral functions as well as peripheral clock scaling
down for additional power optimization.
• Processor wake-up from Power-down mode via external interrupt or Real-time Clock.
• Single power supply chip with Power-On Reset (POR) and Brown-Out Detection
(BOD) circuits:
– CPU operating voltage range of 3.0 V to 3.6 V (3.3 V ± 10 %) with 5 V tolerant I/O
pads

1.4 Applications
• Industrial control
• Medical systems
• General purpose applications
• Communication gateway
• Embedded soft modem
• Access control
• Point-of-sale

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1.5 Device information

Table 1. LPC213x and LPC213x/01 device information
Device Pins SRAM FLASH Number of Number of UART1 UARTs UART1 Fast ADC with
10-bit ADC 10-bit DAC with with BRG with hw GPIOs individual
channels channels modem and auto result
interface autobaud CTS/RTS registers
LPC2131 64 8 kB 32 kB 8
LPC2131/01 64 8 kB 32 kB 8 + + +
LPC2132 64 16 kB 64 kB 8 1
LPC2132/01 64 16 kB 64 kB 8 1 + + +
LPC2134 64 16 kB 128 kB 16 1 +
LPC2134/01 64 16 kB 128 kB 16 1 + + + + +
LPC2136 64 32 kB 256 kB 16 1 +
LPC2136/01 64 32 kB 256 kB 16 1 + + + + +
LPC2138 64 32 kB 512 kB 16 1 +
LPC2138/01 64 32 kB 512 kB 16 1 + + + + +

1.6 Architectural overview

The LPC213x consists of an ARM7TDMI-S CPU with emulation support, the ARM7 Local
Bus for interface to on-chip memory controllers, the AMBA Advanced High-performance
Bus (AHB) for interface to the interrupt controller, and the VLSI Peripheral Bus (APB, a
compatible superset of ARM’s AMBA Advanced Peripheral Bus) for connection to on-chip
peripheral functions. The LPC213x configures the ARM7TDMI-S processor in little-endian
byte order.

AHB peripherals are allocated a 2 megabyte range of addresses at the very top of the
4 gigabyte ARM memory space. Each AHB peripheral is allocated a 16 kB address space
within the AHB address space. LPC213x peripheral functions (other than the interrupt
controller) are connected to the APB bus. The AHB to APB bridge interfaces the APB bus
to the AHB bus. APB peripherals are also allocated a 2 megabyte range of addresses,
beginning at the 3.5 gigabyte address point. Each APB peripheral is allocated a 16 kB
address space within the APB address space.

The connection of on-chip peripherals to device pins is controlled by a Pin Connect Block.
This must be configured by software to fit specific application requirements for the use of
peripheral functions and pins.

1.7 ARM7TDMI-S processor

The ARM7TDMI-S is a general purpose 32-bit microprocessor, which offers high
performance and very low power consumption. The ARM architecture is based on
Reduced Instruction Set Computer (RISC) principles, and the instruction set and related
decode mechanism are much simpler than those of microprogrammed Complex
Instruction Set Computers. This simplicity results in a high instruction throughput and
impressive real-time interrupt response from a small and cost-effective processor core.

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Pipeline techniques are employed so that all parts of the processing and memory systems
can operate continuously. Typically, while one instruction is being executed, its successor
is being decoded, and a third instruction is being fetched from memory.

The ARM7TDMI-S processor also employs a unique architectural strategy known as

THUMB, which makes it ideally suited to high-volume applications with memory
restrictions, or applications where code density is an issue.

The key idea behind THUMB is that of a super-reduced instruction set. Essentially, the
ARM7TDMI-S processor has two instruction sets:

• The standard 32-bit ARM instruction set.

• A 16-bit THUMB instruction set.
The THUMB set’s 16-bit instruction length allows it to approach twice the density of
standard ARM code while retaining most of the ARM’s performance advantage over a
traditional 16-bit processor using 16-bit registers. This is possible because THUMB code
operates on the same 32-bit register set as ARM code.

THUMB code is able to provide up to 65% of the code size of ARM, and 160% of the
performance of an equivalent ARM processor connected to a 16-bit memory system.

The ARM7TDMI-S processor is described in detail in the ARM7TDMI-S Data sheet that
can be found on official ARM website.

1.8 On-chip Flash memory system

The LPC213x incorporates a 32, 64, 128, 256 or 512 kB Flash memory system. This
memory may be used for both code and data storage. Programming of the Flash memory
may be accomplished in several ways: over the serial built-in JTAG interface, using In
System Programming (ISP) and UART0, or by means of In Application Programming
(IAP) capabilities. The application program, using the IAP functions, may also erase
and/or program the Flash while the application is running, allowing a great degree of
flexibility for data storage field firmware upgrades, etc. When the LPC213x on-chip
bootloader is used, 32/64/128/256/500 kB of Flash memory is available for user code
and/or data storage.

The LPC213x Flash memory provides minimum of 100,000 erase/write cycles and 20
years of data-retention.

1.9 On-chip Static RAM (SRAM)

On-chip Static RAM (SRAM) may be used for code and/or data storage. The on-chip
SRAM may be accessed as 8-bits, 16-bits, and 32-bits. The LPC213x provide 8/16/32 kB
of static RAM.

The LPC213x SRAM is designed to be accessed as a byte-addressed memory. Word and

halfword accesses to the memory ignore the alignment of the address and access the
naturally-aligned value that is addressed (so a memory access ignores address bits 0 and
1 for word accesses, and ignores bit 0 for halfword accesses). Therefore valid reads and
writes require data accessed as halfwords to originate from addresses with address line 0
being 0 (addresses ending with 0, 2, 4, 6, 8, A, C, and E in hexadecimal notation) and

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Chapter 1: Introductory information

data accessed as words to originate from addresses with address lines 0 and 1 being 0
(addresses ending with 0, 4, 8, and C in hexadecimal notation). This rule applies to both
off and on-chip memory usage.

The SRAM controller incorporates a write-back buffer in order to prevent CPU stalls
during back-to-back writes. The write-back buffer always holds the last data sent by
software to the SRAM. This data is only written to the SRAM when another write is
requested by software (the data is only written to the SRAM when software does another
write). If a chip reset occurs, actual SRAM contents will not reflect the most recent write
request (i.e. after a "warm" chip reset, the SRAM does not reflect the last write operation).
Any software that checks SRAM contents after reset must take this into account. Two
identical writes to a location guarantee that the data will be present after a Reset.
Alternatively, a dummy write operation before entering idle or power-down mode will
similarly guarantee that the last data written will be present in SRAM after a subsequent
Reset.

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1.10 Block diagram

TMS(3) TDI(3) trace XTAL2

TRST(3) TCK(3) TDO(3) signals XTAL1 RESET

LPC2131, LPC2131/01
LPC2132, LPC2132/01 TEST/DEBUG

TRACE MODULE
LPC2134, LPC2134/01 INTERFACE

EMULATION
SYSTEM
LPC2136, LPC2136/01 PLL
FUNCTIONS
LPC2138, LPC2138/01
ARM7TDMI-S
system
P0[31:0] clock VECTORED
FAST GENERAL
AHB BRIDGE INTERRUPT
PURPOSE I/O
P1[31:16] CONTROLLER

AMBA AHB
(Advanced High-performance Bus)
ARM7 local bus

INTERNAL INTERNAL
SRAM FLASH
CONTROLLER CONTROLLER AHB
DECODER

8/16/32 kB 32/64/128/ AHB TO APB APB

SRAM 256/512 kB BRIDGE DIVIDER
FLASH

APB (ARM
peripheral bus)
SCL0,1
EINT[3:0]
EXTERNAL I2C SERIAL
INTERRUPTS INTERFACES 0 AND 1
SDA0,1

8 × CAP CAPTURE/ SCK0,1

COMPARE SPI AND SSP MOSI0,1
8 × MAT TIMER 0/TIMER 1 SERIAL INTERFACES MISO0,1
SSEL0,1
AD0[7:0]
A/D CONVERTERS TXD0,1
0 AND 1(1)
AD1[7:0](1) UART0/UART1 RXD0,1
DSR1(1),CTS1(1)
RTS1(1), DTR1(1)
AOUT(2) D/A CONVERTER(2) DCD1(1), RI1(1)
RTCX1
REAL TIME CLOCK RTCX2
P0[31:0] GENERAL VBAT
PURPOSE I/O
P1[31:16]
WATCHDOG
TIMER
PWM[6:1] PWM0

SYSTEM
CONTROL

002aab067

(1) Not available on LPC2131 and LPC2131/01.

(2) Not available on LPC2131, LPC2131/01, LPC2132, and LPC2132/01.
(3) Pins shared with GPIO.
Fig 1. LPC213x block diagram.

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Rev. 3 — 4 October 2010 User manual

2.1 Memory maps

The LPC213x incorporates several distinct memory regions, shown in the following
figures. Figure 2 shows the overall map of the entire address space from the user
program viewpoint following reset. The interrupt vector area supports address remapping,
which is described later in this section.

4.0 GB 0xFFFF FFFF

AHB PERIPHERALS
3.75 GB 0xF000 0000

APB PERIPHERALS
3.5 GB 0xE000 0000

3.0 GB RESERVED ADDRESS SPACE 0xC000 0000

2.0 GB 0x8000 0000

BOOT BLOCK
(12 kB REMAPPED FROM ON-CHIP FLASH MEMORY)
0x7FFF D000

RESERVED ADDRESS SPACE

0x4000 8000
0x4000 7FFF
32 kB ON-CHIP STATIC RAM
(LPC2136, LPC2136/01, LPC2138, LPC2138/01) 0x4000 4000
0x4000 3FFF
16 kB ON-CHIP STATIC RAM
(LPC2132, LPC2132/01, LPC2134, LPC2134/01) 0x4000 2000
0x4000 1FFF
8 kB ON-CHIP STATIC RAM
1.0 GB (LPC2131, LPC2131/01) 0x4000 0000

RESERVED ADDRESS SPACE

0x0008 0000
0x0007 FFFF
TOTAL OF 512 kB ON-CHIP NON-VOLATILE MEMORY
(LPC2138, LPC2138/01) 0x0004 0000
0x0003 FFFF
TOTAL OF 256 kB ON-CHIP NON-VOLATILE MEMORY
(LPC2136, LPC2136/01) 0x0002 0000
0x0001 FFFF
TOTAL OF 128 kB ON-CHIP NON-VOLATILE MEMORY
(LPC2134, LPC2134/01) 0x0001 0000
0x0000 FFFF
TOTAL OF 64 kB ON-CHIP NON-VOLATILE MEMORY
(LPC2132, LPC2132/01) 0x0000 8000
0x0000 7FFF
TOTAL OF 32 kB ON-CHIP NON-VOLATILE MEMORY
0.0 GB (LPC2131, LPC2131/01) 0x0000 0000

Fig 2. System memory map

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4.0 GB
0xFFFF FFFF
AHB PERIPHERALS

4.0 GB - 2 MB 0xFFE0 0000

0xFFDF FFFF

RESERVED

3.75 GB 0xF000 0000

0xEFFF FFFF

RESERVED

3.5 GB + 2 MB 0xE020 0000

0xE01F FFFF
APB PERIPHERALS

3.5 GB 0xE000 0000

AHB section is 128 x 16 kB blocks (totaling 2 MB).

APB section is 128 x 16 kB blocks (totaling 2MB).
Fig 3. Peripheral memory map

Figure 3 through Figure 4 and Table 2 show different views of the peripheral address
space. Both the AHB and APB peripheral areas are 2 megabyte spaces which are divided
up into 128 peripherals. Each peripheral space is 16 kilobytes in size. This allows
simplifying the address decoding for each peripheral. All peripheral register addresses are

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word aligned (to 32-bit boundaries) regardless of their size. This eliminates the need for
byte lane mapping hardware that would be required to allow byte (8-bit) or half-word
(16-bit) accesses to occur at smaller boundaries. An implication of this is that word and
half-word registers must be accessed all at once. For example, it is not possible to read or
write the upper byte of a word register separately.

VECTORED INTERRUPT CONTROLLER 0xFFFF F000 (4G - 4K)

0xFFFF C000

(AHB PERIPHERAL #126)

0xFFFF 8000

(AHB PERIPHERAL #125)

0xFFFF 4000

(AHB PERIPHERAL #124)

0xFFFF 0000

0xFFE1 0000

(AHB PERIPHERAL #3)

0xFFE0 C000

(AHB PERIPHERAL #2)

0xFFE0 8000

(AHB PERIPHERAL #1)

0xFFE0 4000

(AHB PERIPHERAL #0)

0xFFE0 0000

Fig 4. AHB peripheral map

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Table 2. APB peripheries and base addresses

APB peripheral Base address Peripheral name
0 0xE000 0000 Watchdog timer
1 0xE000 4000 Timer 0
2 0xE000 8000 Timer 1
3 0xE000 C000 UART0
4 0xE001 0000 UART1
5 0xE001 4000 PWM
6 0xE001 8000 Not used
7 0xE001 C000 I2C0
8 0xE002 0000 SPI0
9 0xE002 4000 RTC
10 0xE002 8000 GPIO
11 0xE002 C000 Pin connect block
12 0xE003 0000 Not used
13 0xE003 4000 10 bit AD0
14-22 0xE003 8000 - Not used
0xE005 8000
23 0xE005 C000 I2C1
24 0xE006 0000 10 bit AD1
25 0xE006 4000 Not used
26 0xE006 8000 SSP
27 0xE006 C000 DAC
28 - 126 0xE007 0000 - Not used
0xE01F 8000
127 0xE01F C000 System control block

2.2 LPC213x memory re-mapping and boot block

2.2.1 Memory map concepts and operating modes

The basic concept on the LPC213x is that each memory area has a "natural" location in
the memory map. This is the address range for which code residing in that area is written.
The bulk of each memory space remains permanently fixed in the same location,
eliminating the need to have portions of the code designed to run in different address
ranges.

Because of the location of the interrupt vectors on the ARM7 processor (at addresses
0x0000 0000 through 0x0000 001C, as shown in Table 3 below), a small portion of the
Boot Block and SRAM spaces need to be re-mapped in order to allow alternative uses of
interrupts in the different operating modes described in Table 4. Re-mapping of the
interrupts is accomplished via the Memory Mapping Control feature (Section 4.7 “Memory
mapping control” on page 32).

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Table 3. ARM exception vector locations

Address Exception
0x0000 0000 Reset
0x0000 0004 Undefined Instruction
0x0000 0008 Software Interrupt
0x0000 000C Prefetch Abort (instruction fetch memory fault)
0x0000 0010 Data Abort (data access memory fault)
0x0000 0014 Reserved

Note: Identified as reserved in ARM documentation, this location is used

by the Boot Loader as the Valid User Program key. This is described in
detail in "Flash Memory System and Programming" chapter.
0x0000 0018 IRQ
0x0000 001C FIQ

Table 4. LPC213x memory mapping modes

Mode Activation Usage
Boot Hardware The Boot Loader always executes after any reset. The Boot Block
Loader activation by interrupt vectors are mapped to the bottom of memory to allow
mode any Reset handling exceptions and using interrupts during the Boot Loading
process.
User Software Activated by Boot Loader when a valid User Program Signature is
Flash activation by recognized in memory and Boot Loader operation is not forced.
mode Boot code Interrupt vectors are not re-mapped and are found in the bottom of the
Flash memory.
User RAM Software Activated by a User Program as desired. Interrupt vectors are
mode activation by re-mapped to the bottom of the Static RAM.
User program

2.2.2 Memory re-mapping

In order to allow for compatibility with future derivatives, the entire Boot Block is mapped
to the top of the on-chip memory space. In this manner, the use of larger or smaller flash
modules will not require changing the location of the Boot Block (which would require
changing the Boot Loader code itself) or changing the mapping of the Boot Block interrupt
vectors. Memory spaces other than the interrupt vectors remain in fixed locations.
Figure 5 shows the on-chip memory mapping in the modes defined above.

The portion of memory that is re-mapped to allow interrupt processing in different modes
includes the interrupt vector area (32 bytes) and an additional 32 bytes, for a total of
64 bytes. The re-mapped code locations overlay addresses 0x0000 0000 through
0x0000 003F. A typical user program in the Flash memory can place the entire FIQ
handler at address 0x0000 001C without any need to consider memory boundaries. The
vector contained in the SRAM, external memory, and Boot Block must contain branches to
the actual interrupt handlers, or to other instructions that accomplish the branch to the
interrupt handlers.

There are three reasons this configuration was chosen:

1. To give the FIQ handler in the Flash memory the advantage of not having to take a
memory boundary caused by the remapping into account.
UM10120 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved.

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2. Minimize the need to for the SRAM and Boot Block vectors to deal with arbitrary
boundaries in the middle of code space.
3. To provide space to store constants for jumping beyond the range of single word
branch instructions.

Re-mapped memory areas, including the Boot Block and interrupt vectors, continue to
appear in their original location in addition to the re-mapped address.

Details on re-mapping and examples can be found in Section 4.7 “Memory mapping
control” on page 32.

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2.0 GB 0x8000 0000

12 kB BOOT BLOCK 0x7FFF FFFF
(RE-MAPPED FROM ON-CHIP FLASH MEMORY)
2.0 GB - 12 kB
BOOT BLOCK INTERRUPT VECTORS 0x7FFF D000
0x7FFF CFFF

RESERVED FOR ON-CHIP MEMORY

0x4000 8000
0x4000 7FFF

32 kB ON-CHIP SRAM

1.0 GB (SRAM INTERRUPT VECTORS) 0x4000 0000

0x3FFF FFFF

RESERVED FOR ON-CHIP MEMORY

0x0008 0000
12 kB BOOT BLOCK RE-MAPPED TO HIGHER ADDRESS RANGE 0x0007 FFFF

512 kB ON-CHIP NON-VOLATILE MEMORY

ACTIVE INTERRUPT VECTORS

0.0 GB (FROM FLASH, SRAM, BOOT ROM, OR EXT MEMORY) 0x0000 0000

Fig 5. Map of lower memory is showing re-mapped and re-mappable areas (LPC2138
and LPC2138/01 with 512 kB Flash)

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2.3 Prefetch abort and data abort exceptions

The LPC213x generates the appropriate bus cycle abort exception if an access is
attempted for an address that is in a reserved or unassigned address region. The regions
are:

• Areas of the memory map that are not implemented for a specific ARM derivative. For
the LPC213x, this is:
– Address space between On-Chip Non-Volatile Memory and On-Chip SRAM,
labelled "Reserved Address Space" in Figure 2 and Figure 5. For 32 kB Flash
device this is memory address range from 0x0000 8000 to 0x3FFF FFFF, for 64 kB
Flash device this is memory address range from 0x0001 0000 to 0x3FFF FFFF, for
128 kB Flash device this is memory address range from 0x0002 0000 to
0x3FFF FFFF, for 256 kB Flash device this is memory address range from
0x0004 0000 to 0x3FFF FFFF while for 512 kB Flash device this range is from
0x0008 0000 to 0x3FFF FFFF.
– Address space between On-Chip Static RAM and the Boot Block. Labelled
"Reserved Address Space" in Figure 2. For 8 kB SRAM device this is memory
address range from 0x4000 2000 to 0x7FFF CFFF, for 16 kB SRAM device this is
memory address range from 0x4000 4000 to 0x7FFF CFFF, while for 32 kB SRAM
device this range is from 0x4000 8000 to 0x7FFF CFFF.
– Address space between 0x8000 0000 and 0xDFFF FFFF, labelled "Reserved
Address Space".
– Reserved regions of the AHB and APB spaces. See Figure 3.
• Unassigned AHB peripheral spaces. See Figure 4.
• Unassigned APB peripheral spaces. See Table 2.
For these areas, both attempted data access and instruction fetch generate an exception.
In addition, a Prefetch Abort exception is generated for any instruction fetch that maps to
an AHB or APB peripheral address.

Within the address space of an existing APB peripheral, a data abort exception is not
generated in response to an access to an undefined address. Address decoding within
each peripheral is limited to that needed to distinguish defined registers within the
peripheral itself. For example, an access to address 0xE000 D000 (an undefined address
within the UART0 space) may result in an access to the register defined at address
0xE000 C000. Details of such address aliasing within a peripheral space are not defined
in the LPC213x documentation and are not a supported feature.

Note that the ARM core stores the Prefetch Abort flag along with the associated
instruction (which will be meaningless) in the pipeline and processes the abort only if an
attempt is made to execute the instruction fetched from the illegal address. This prevents
accidental aborts that could be caused by prefetches that occur when code is executed
very near a memory boundary.

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3.1 Introduction
The MAM block in the LPC213x maximizes the performance of the ARM processor when
it is running code in Flash memory but does so using a single Flash bank.

3.2 Operation
Simply put, the Memory Accelerator Module (MAM) attempts to have the next ARM
instruction that will be needed in its latches in time to prevent CPU fetch stalls. The
LPC213x uses one bank of Flash memory, compared to the two banks used on
predecessor devices. It includes three 128-bit buffers called the Prefetch Buffer, the
Branch Trail Buffer and the data buffer. When an Instruction Fetch is not satisfied by either
the Prefetch or Branch Trail Buffer, nor has a prefetch been initiated for that line, the ARM
is stalled while a fetch is initiated for the 128-bit line. If a prefetch has been initiated but not
yet completed, the ARM is stalled for a shorter time. Unless aborted by a data access, a
prefetch is initiated as soon as the Flash has completed the previous access. The
prefetched line is latched by the Flash module, but the MAM does not capture the line in
its prefetch buffer until the ARM core presents the address from which the prefetch has
been made. If the core presents a different address from the one from which the prefetch
has been made, the prefetched line is discarded.

The Prefetch and Branch Trail buffers each include four 32-bit ARM instructions or eight
16-bit Thumb instructions. During sequential code execution, typically the Prefetch Buffer
contains the current instruction and the entire Flash line that contains it.

The MAM differentiates between instruction and data accesses. Code and data accesses
use separate 128-bit buffers. 3 of every 4 sequential 32-bit code or data accesses "hit" in
the buffer without requiring a Flash access (7 of 8 sequential 16-bit accesses, 15 of every
16 sequential byte accesses). The fourth (eighth, 16th) sequential data access must
access Flash, aborting any prefetch in progress. When a Flash data access is concluded,
any prefetch that had been in progress is re-initiated.

Timing of Flash read operations is programmable and is described later in this section.

In this manner, there is no code fetch penalty for sequential instruction execution when the
CPU clock period is greater than or equal to one fourth of the Flash access time. The
average amount of time spent doing program branches is relatively small (less than 25%)
and may be minimized in ARM (rather than Thumb) code through the use of the
conditional execution feature present in all ARM instructions. This conditional execution
may often be used to avoid small forward branches that would otherwise be necessary.

Branches and other program flow changes cause a break in the sequential flow of
instruction fetches described above. The Branch Trail Buffer captures the line to which
such a non-sequential break occurs. If the same branch is taken again, the next
instruction is taken from the Branch Trail Buffer. When a branch outside the contents of
the Prefetch and Branch Trail Buffer is taken, a stall of several clocks is needed to load the
Branch Trail buffer. Subsequently, there will typically be no further instruction fetch delays
until a new and different branch occurs.

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3.3 MAM blocks

The Memory Accelerator Module is divided into several functional blocks:

• A Flash Address Latch and an incrementor function to form prefetch addresses

• A 128-bit Prefetch Buffer and an associated Address latch and comparator
• A 128-bit Branch Trail Buffer and an associated Address latch and comparator
• A 128-bit Data Buffer and an associated Address latch and comparator
• Control logic
• Wait logic

Figure 6 shows a simplified block diagram of the Memory Accelerator Module data paths.

In the following descriptions, the term “fetch” applies to an explicit Flash read request from
the ARM. “Pre-fetch” is used to denote a Flash read of instructions beyond the current
processor fetch address.

3.3.1 Flash memory bank

There is one bank of Flash memory with the LPC213x MAM.

Flash programming operations are not controlled by the MAM, but are handled as a
separate function. A “boot block” sector contains Flash programming algorithms that may
be called as part of the application program, and a loader that may be run to allow serial
programming of the Flash memory.

MEMORY ADDRESS

FLASH MEMORY BANK

BUS
ARM LOCAL BUS
INTERFACE

BUFFERS

Fig 6. Simplified block diagram of the Memory Accelerator Module (MAM)

3.3.2 Instruction latches and data latches

Code and Data accesses are treated separately by the Memory Accelerator Module.
There is a 128-bit Latch, a 15-bit Address

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Latch, and a 15-bit comparator associated with each buffer (prefetch, branch trail, and
data). Each 128-bit latch holds 4 words (4 ARM instructions, or 8 Thumb instructions).
Also associated with each buffer are 32 4:1 Multiplexers that select the requested word
from the 128-bit line.

Each Data access that is not in the Data latch causes a Flash fetch of 4 words of data,
which are captured in the Data latch. This speeds up sequential Data operations, but has
little or no effect on random accesses.

3.3.3 Flash programming issues

Since the Flash memory does not allow accesses during programming and erase
operations, it is necessary for the MAM to force the CPU to wait if a memory access to a
Flash address is requested while the Flash module is busy. (This is accomplished by
asserting the ARM7TDMI-S local bus signal CLKEN.) Under some conditions, this delay
could result in a Watchdog time-out. The user will need to be aware of this possibility and
take steps to insure that an unwanted Watchdog reset does not cause a system failure
while programming or erasing the Flash memory.

In order to preclude the possibility of stale data being read from the Flash memory, the
LPC213x MAM holding latches are automatically invalidated at the beginning of any Flash
programming or erase operation. Any subsequent read from a Flash address will cause a
new fetch to be initiated after the Flash operation has completed.

3.4 MAM operating modes

Three modes of operation are defined for the MAM, trading off performance for ease of
predictability:

Mode 0: MAM off. All memory requests result in a Flash read operation (see note 2
below). There are no instruction prefetches.
Mode 1: MAM partially enabled. Sequential instruction accesses are fulfilled from the
holding latches if the data is present. Instruction prefetch is enabled. Non-sequential
instruction accesses initiate Flash read operations (see note 2 below). This means that
all branches cause memory fetches. All data operations cause a Flash read because
buffered data access timing is hard to predict and is very situation dependent.
Mode 2: MAM fully enabled. Any memory request (code or data) for a value that is
contained in one of the corresponding holding latches is fulfilled from the latch.
Instruction prefetch is enabled. Flash read operations are initiated for instruction
prefetch and code or data values not available in the corresponding holding latches.

Table 5. MAM responses to program accesses of various types

Program Memory Request Type MAM Mode
0 1 2
Sequential access, data in latches Initiate Fetch[2] Use Latched Use Latched
Data[1] Data[1]
Sequential access, data not in latches Initiate Fetch Initiate Fetch[1] Initiate Fetch[1]
Non-sequential access, data in latches Initiate Fetch[2] Initiate Fetch[1][2] Use Latched
Data[1]
Non-sequential access, data not in latches Initiate Fetch Initiate Fetch[1] Initiate Fetch[1]

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[1] Instruction prefetch is enabled in modes 1 and 2.

[2] The MAM actually uses latched data if it is available, but mimics the timing of a Flash read operation. This
saves power while resulting in the same execution timing. The MAM can truly be turned off by setting the
fetch timing value in MAMTIM to one clock.

Table 6. MAM responses to data and DMA accesses of various types

Data Memory Request Type MAM Mode
0 1 2
Sequential access, data in latches Initiate Fetch[1] Initiate Fetch[1] Use Latched
Data
Sequential access, data not in latches Initiate Fetch Initiate Fetch Initiate Fetch
Non-sequential access, data in latches Initiate Fetch[1] Initiate Fetch[1] Use Latched
Data
Non-sequential access, data not in latches Initiate Fetch Initiate Fetch Initiate Fetch

[1] The MAM actually uses latched data if it is available, but mimics the timing of a Flash read operation. This
saves power while resulting in the same execution timing. The MAM can truly be turned off by setting the
fetch timing value in MAMTIM to one clock.

3.5 MAM configuration

After reset the MAM defaults to the disabled state. Software can turn memory access
acceleration on or off at any time. This allows most of an application to be run at the
highest possible performance, while certain functions can be run at a somewhat slower
but more predictable rate if more precise timing is required.

3.6 Register description

All registers, regardless of size, are on word address boundaries. Details of the registers
appear in the description of each function.

Table 7. Summary of MAM registers

Name Description Access Reset Address
value[1]
MAMCR Memory Accelerator Module Control Register. R/W 0x0 0xE01F C000
Determines the MAM functional mode, that is, to
what extent the MAM performance enhancements
are enabled. See Table 8.
MAMTIM Memory Accelerator Module Timing control. R/W 0x07 0xE01F C004
Determines the number of clocks used for Flash
memory fetches (1 to 7 processor clocks).

[1] Reset value reflects the data stored in used bits only. It does not include reserved bits content.

3.7 MAM Control Register (MAMCR - 0xE01F C000)

Two configuration bits select the three MAM operating modes, as shown in Table 8.
Following Reset, MAM functions are disabled. Changing the MAM operating mode causes
the MAM to invalidate all of the holding latches, resulting in new reads of Flash
information as required.

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Table 8. MAM Control Register (MAMCR - address 0xE01F C000) bit description
Bit Symbol Value Description Reset
value
1:0 MAM_mode 00 MAM functions disabled 0
_control 01 MAM functions partially enabled
10 MAM functions fully enabled
11 Reserved. Not to be used in the application.
7:2 - - Reserved, user software should not write ones to reserved NA
bits. The value read from a reserved bit is not defined.

3.8 MAM Timing register (MAMTIM - 0xE01F C004)

The MAM Timing register determines how many CCLK cycles are used to access the
Flash memory. This allows tuning MAM timing to match the processor operating
frequency. Flash access times from 1 clock to 7 clocks are possible. Single clock Flash
accesses would essentially remove the MAM from timing calculations. In this case the
MAM mode may be selected to optimize power usage.

Table 9. MAM Timing register (MAMTIM - address 0xE01F C004) bit description
Bit Symbol Value Description Reset
value
2:0 MAM_fetch_ 000 0 - Reserved. 07
cycle_timing
001 1 - MAM fetch cycles are 1 processor clock (CCLK) in
duration
010 2 - MAM fetch cycles are 2 CCLKs in duration
011 3 - MAM fetch cycles are 3 CCLKs in duration
100 4 - MAM fetch cycles are 4 CCLKs in duration
101 5 - MAM fetch cycles are 5 CCLKs in duration
110 6 - MAM fetch cycles are 6 CCLKs in duration
111 7 - MAM fetch cycles are 7 CCLKs in duration
Warning: These bits set the duration of MAM Flash fetch operations
as listed here. Improper setting of this value may result in incorrect
operation of the device.
7:3 - - Reserved, user software should not write ones to reserved NA
bits. The value read from a reserved bit is not defined.

3.9 MAM usage notes

When changing MAM timing, the MAM must first be turned off by writing a zero to
MAMCR. A new value may then be written to MAMTIM. Finally, the MAM may be turned
on again by writing a value (1 or 2) corresponding to the desired operating mode to
MAMCR.

For system clock slower than 20 MHz, MAMTIM can be 001. For system clock between
20 MHz and 40 MHz, Flash access time is suggested to be 2 CCLKs, while in systems
with system clock faster than 40 MHz, 3 CCLKs are proposed.

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4.1 Summary of system control block functions

The System Control Block includes several system features and control registers for a
number of functions that are not related to specific peripheral devices. These include:

• Crystal Oscillator
• External Interrupt Inputs
• Miscellaneous System Controls and Status
• Memory Mapping Control
• PLL
• Power Control
• Reset
• APB Divider
• Wake-up Timer

Each type of function has its own register(s) if any are required and unneeded bits are
defined as reserved in order to allow future expansion. Unrelated functions never share
the same register addresses

4.2 Pin description

Table 10 shows pins that are associated with System Control block functions.

Table 10. Pin summary

Pin name Pin Pin description
direction
XTAL1 Input Crystal Oscillator Input - Input to the oscillator and internal clock
generator circuits
XTAL2 Output Crystal Oscillator Output - Output from the oscillator amplifier
EINT0 Input External Interrupt Input 0 - An active low/high level or
falling/rising edge general purpose interrupt input. This pin may be
used to wake up the processor from Idle or Power-down modes.
Pins P0.1 and P0.16 can be selected to perform EINT0 function.
EINT1 Input External Interrupt Input 1 - See the EINT0 description above.
Pins P0.3 and P0.14 can be selected to perform EINT1 function.
Important: LOW level on pin P0.14 immediately after reset is
considered as an external hardware request to start the ISP
command handler. More details on ISP and Serial Boot Loader can
be found in "Flash Memory System and Programming" chapter.

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Table 10. Pin summary

Pin name Pin Pin description
direction
EINT2 Input External Interrupt Input 2 - See the EINT0 description above.
Pins P0.7 and P0.15 can be selected to perform EINT2 function.
EINT3 Input External Interrupt Input 3 - See the EINT0 description above.
Pins P0.9, P0.20 and P0.30 can be selected to perform EINT3
function.
RESET Input External Reset input - A LOW on this pin resets the chip, causing
I/O ports and peripherals to take on their default states, and the
processor to begin execution at address 0x0000 0000.

4.3 Register description

All registers, regardless of size, are on word address boundaries. Details of the registers
appear in the description of each function.

Table 11. Summary of system control registers

Name Description Access Reset Address
value[1]
External Interrupts
EXTINT External Interrupt Flag Register R/W 0 0xE01F C140
INTWAKE External Interrupt Wakeup Register R/W 0 0xE01F C144
EXTMODE External Interrupt Flag register R/W 0 0xE01F C148
EXTPOLAR External Interrupt Wakeup Register R/W 0 0xE01F C14C
Memory Mapping Control
MEMMAP Memory Mapping Control R/W 0 0xE01F C040
Phase Locked Loop
PLLCON PLL Control Register R/W 0 0xE01F C080
PLLCFG PLL Configuration Register R/W 0 0xE01F C084
PLLSTAT PLL Status Register RO 0 0xE01F C088
PLLFEED PLL Feed Register WO NA 0xE01F C08C
Power Control
PCON Power Control Register R/W 0 0xE01F C0C0
PCONP Power Control for Peripherals R/W 0x03BE 0xE01F C0C4
APB Divider
APBDIV APB Divider Control R/W 0 0xE01F C100
Reset
RSID Reset Source Identification Register R/W 0 0xE01F C180
Code Security/Debugging
CSPR Code Security Protection Register RO o 0xE01F C184
Syscon Miscellaneous Registers[2]
SCS System Controls and Status R/W 0 0xE01F C1A0

[1] Reset value reflects the data stored in used bits only. It does not include reserved bits content.
[2] Available in LPC213x/01devices only.

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4.4 Crystal oscillator

While an input signal of 50-50 duty cycle within a frequency range from 1 MHz to 50 MHz
can be used by the LPC213x if supplied to its input XTAL1 pin, this microcontroller’s
onboard oscillator circuit supports external crystals in the range of 1 MHz to 30 MHz only.
If the on-chip PLL system or the boot-loader is used, the input clock frequency is limited to
an exclusive range of 10 MHz to 25 MHz.

The oscillator output frequency is called FOSC and the ARM processor clock frequency is
referred to as CCLK for purposes of rate equations, etc. elsewhere in this document. FOSC
and CCLK are the same value unless the PLL is running and connected. Refer to the
Section 4.8 “Phase Locked Loop (PLL)” on page 33 for details and frequency limitations.

The onboard oscillator in the LPC213x can operate in one of two modes: slave mode and
oscillation mode.

In slave mode the input clock signal should be coupled by means of a capacitor of 100 pF
(CC in Figure 7, drawing a), with an amplitude of at least 200 mVrms. The X2 pin in this
configuration can be left not connected. If slave mode is selected, the FOSC signal of
50-50 duty cycle can range from 1 MHz to 50 MHz.

External components and models used in oscillation mode are shown in Figure 7,
drawings b and c, and in Table 12. Since the feedback resistance is integrated on chip,
only a crystal and the capacitances CX1 and CX2 need to be connected externally in case
of fundamental mode oscillation (the fundamental frequency is represented by L, CL and
RS). Capacitance CP in Figure 7, drawing c, represents the parallel package capacitance
and should not be larger than 7 pF. Parameters FC, CL, RS and CP are supplied by the
crystal manufacturer.

Choosing an oscillation mode as an on-board oscillator mode of operation limits FOSC

clock selection to 1 MHz to 30 MHz.

LPC213x LPC213x

XTAL1 XTAL2 XTAL1 XTAL2

<=>
CC CL CP
Xtal
Clock CX1 CX2
RS

a) b) c)

Fig 7. Oscillator modes and models: a) slave mode of operation, b) oscillation mode of operation, c) external
crystal model used for CX1/X2 evaluation

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Table 12. Recommended values for CX1/X2 in oscillation mode (crystal and external
components parameters)
Fundamental Crystal load Maximum crystal External load
oscillation frequency capacitance CL series resistance RS capacitors CX1, CX2
FC
1 MHz - 5 MHz 10 pF NA NA
20 pF NA NA
30 pF < 300 Ω 58 pF, 58 pF
5 MHz - 10 MHz 10 pF < 300 Ω 18 pF, 18 pF
20 pF < 300 Ω 38 pF, 38 pF
30 pF < 300 Ω 58 pF, 58 pF
10 MHz - 15 MHz 10 pF < 300 Ω 18 pF, 18 pF
20 pF < 220 Ω 38 pF, 38 pF
30 pF < 140 Ω 58 pF, 58 pF
15 MHz - 20 MHz 10 pF < 220 Ω 18 pF, 18 pF
20 pF < 140 Ω 38 pF, 38 pF
30 pF < 80 Ω 58 pF, 58 pF
20 MHz - 25 MHz 10 pF < 160 Ω 18 pF, 18 pF
20 pF < 90 Ω 38 pF, 38 pF
30 pF < 50 Ω 58 pF, 58 pF
25 MHz - 30 MHz 10 pF < 130 Ω 18 pF, 18 pF
20 pF < 50 Ω 38 pF, 38 pF
30 pF NA NA

f OSC selection

true on-chip PLL used

in application?

false

true ISP used for initial

code download?

false

external crystal true

oscillator used?

false

MIN fOSC = 10 MHz MIN fOSC = 1 MHz MIN fOSC = 1 MHz

MAX fOSC = 25 MHz MAX fOSC = 50 MHz MAX fOSC = 30 MHz

mode a and/or b mode a mode b

Fig 8. FOSC selection algorithm

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4.5 External interrupt inputs

The LPC213x includes four External Interrupt Inputs as selectable pin functions. The
External Interrupt Inputs can optionally be used to wake up the processor from
Power-down mode.

4.5.1 Register description

The external interrupt function has four registers associated with it. The EXTINT register
contains the interrupt flags, and the EXTWAKEUP register contains bits that enable
individual external interrupts to wake up the microcontroller from Power-down mode. The
EXTMODE and EXTPOLAR registers specify the level and edge sensitivity parameters.

Table 13. External interrupt registers

Name Description Access Reset Address
value[1]
EXTINT The External Interrupt Flag Register contains R/W 0 0xE01F C140
interrupt flags for EINT0, EINT1, EINT2 and
EINT3. See Table 14.
INTWAKE The Interrupt Wake-up Register contains four R/W 0 0xE01F C144
enable bits that control whether each external
interrupt will cause the processor to wake up
from Power-down mode. See Table 15.
EXTMODE The External Interrupt Mode Register controls R/W 0 0xE01F C148
whether each pin is edge- or level sensitive.
EXTPOLAR The External Interrupt Polarity Register controls R/W 0 0xE01F C14C
which level or edge on each pin will cause an
interrupt.

[1] Reset value reflects the data stored in used bits only. It does not include reserved bits content.

4.5.2 External Interrupt Flag register (EXTINT - 0xE01F C140)

When a pin is selected for its external interrupt function, the level or edge on that pin
(selected by its bits in the EXTPOLAR and EXTMODE registers) will set its interrupt flag in
this register. This asserts the corresponding interrupt request to the VIC, which will cause
an interrupt if interrupts from the pin are enabled.

Writing ones to bits EINT0 through EINT3 in EXTINT register clears the corresponding
bits. In level-sensitive mode this action is efficacious only when the pin is in its inactive
state.

Once a bit from EINT0 to EINT3 is set and an appropriate code starts to execute (handling
wake-up and/or external interrupt), this bit in EXTINT register must be cleared. Otherwise
the event that was just triggered by activity on the EINT pin will not be recognized in the
future.

Important: whenever a change of external interrupt operating mode (i.e. active

level/edge) is performed (including the initialization of an external interrupt), the
corresponding bit in the EXTINT register must be cleared! For details see
Section 4.5.4 “External Interrupt Mode register (EXTMODE - 0xE01F C148)” and
Section 4.5.5 “External Interrupt Polarity register (EXTPOLAR - 0xE01F C14C)”.

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For example, if a system wakes up from power-down using a low level on external
interrupt 0 pin, its post-wake-up code must reset the EINT0 bit in order to allow future
entry into the power-down mode. If the EINT0 bit is left set to 1, subsequent attempt(s) to
invoke power-down mode will fail. The same goes for external interrupt handling.

More details on power-down mode will be discussed in the following chapters.

Table 14. External Interrupt Flag register (EXTINT - address 0xE01F C140) bit description
Bit Symbol Description Reset
value
0 EINT0 In level-sensitive mode, this bit is set if the EINT0 function is selected for its pin, and the pin is in 0
its active state. In edge-sensitive mode, this bit is set if the EINT0 function is selected for its pin,
and the selected edge occurs on the pin.
Up to two pins can be selected to perform the EINT0 function (see P0.1 and P0.16 description in
"Pin Configuration" chapter)
This bit is cleared by writing a one to it, except in level sensitive mode when the pin is in its
active state (e.g. if EINT0 is selected to be low level sensitive and a low level is present on the
corresponding pin, this bit can not be cleared; this bit can be cleared only when the signal on the
pin becomes high).
1 EINT1 In level-sensitive mode, this bit is set if the EINT1 function is selected for its pin, and the pin is in 0
its active state. In edge-sensitive mode, this bit is set if the EINT1 function is selected for its pin,
and the selected edge occurs on the pin.
Up to two pins can be selected to perform the EINT1 function (see P0.3 and P0.14 description in
"Pin Configuration" chapter)
This bit is cleared by writing a one to it, except in level sensitive mode when the pin is in its
active state (e.g. if EINT1 is selected to be low level sensitive and a low level is present on the
corresponding pin, this bit can not be cleared; this bit can be cleared only when the signal on the
pin becomes high).
2 EINT2 In level-sensitive mode, this bit is set if the EINT2 function is selected for its pin, and the pin is in 0
its active state. In edge-sensitive mode, this bit is set if the EINT2 function is selected for its pin,
and the selected edge occurs on the pin.
Up to two pins can be selected to perform the EINT2 function (see P0.7 and P0.15 description in
"Pin Configuration" chapter )
This bit is cleared by writing a one to it, except in level sensitive mode when the pin is in its
active state (e.g. if EINT2 is selected to be low level sensitive and a low level is present on the
corresponding pin, this bit can not be cleared; this bit can be cleared only when the signal on the
pin becomes high).
3 EINT3 In level-sensitive mode, this bit is set if the EINT3 function is selected for its pin, and the pin is in 0
its active state. In edge-sensitive mode, this bit is set if the EINT3 function is selected for its pin,
and the selected edge occurs on the pin.
Up to three pins can be selected to perform the EINT3 function (see P0.9, P0.20 and P0.30
description in "Pin Configuration" chapter)
This bit is cleared by writing a one to it, except in level sensitive mode when the pin is in its
active state (e.g. if EINT3 is selected to be low level sensitive and a low level is present on the
corresponding pin, this bit can not be cleared; this bit can be cleared only when the signal on the
pin becomes high).
7:4 - Reserved, user software should not write ones to reserved bits. The value read from a reserved NA
bit is not defined.

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4.5.3 Interrupt Wake-up register (INTWAKE - 0xE01F C144)

Enable bits in the INTWAKE register allow the external interrupts to wake up the
processor if it is in Power-down mode. The related EINTn function must be mapped to the
pin in order for the wake-up process to take place. It is not necessary for the interrupt to
be enabled in the Vectored Interrupt Controller for a wake-up to take place. This
arrangement allows additional capabilities, such as having an external interrupt input
wake up the processor from Power-down mode without causing an interrupt (simply
resuming operation), or allowing an interrupt to be enabled during Power-down without
waking the processor up if it is asserted (eliminating the need to disable the interrupt if the
wake-up feature is not desirable in the application).

For an external interrupt pin to be a source that would wake up the microcontroller from
Power-down mode, it is also necessary to clear the corresponding bit in the External
Interrupt Flag register (Section 4.5.2 on page 26).

Table 15. Interrupt Wakeup register (INTWAKE - address 0xE01F C144) bit description
Bit Symbol Description Reset
value
0 EXTWAKE0 When one, assertion of EINT0 will wake up the processor from 0
Power-down mode.
1 EXTWAKE1 When one, assertion of EINT1 will wake up the processor from 0
Power-down mode.
2 EXTWAKE2 When one, assertion of EINT2 will wake up the processor from 0
Power-down mode.
3 EXTWAKE3 When one, assertion of EINT3 will wake up the processor from 0
Power-down mode.
13:4 - Reserved, user software should not write ones to reserved bits. NA
The value read from a reserved bit is not defined.
14 BODWAKE When one, a BOD interrupt will wake up the processor from 0
Power-down mode.
15 RTCWAKE When one, assertion of an RTC interrupt will wake up the 0
processor from Power-down mode.

4.5.4 External Interrupt Mode register (EXTMODE - 0xE01F C148)

The bits in this register select whether each EINT pin is level- or edge-sensitive. Only pins
that are selected for the EINT function (see chapter Pin Connect Block on page 58) and
enabled via the VICIntEnable register (Section 7.4.4 “Interrupt Enable register
(VICIntEnable - 0xFFFF F010)” on page 68) can cause interrupts from the External
Interrupt function (though of course pins selected for other functions may cause interrupts
from those functions).

Note: Software should only change a bit in this register when its interrupt is
disabled in the VICIntEnable register, and should write the corresponding 1 to the
EXTINT register before enabling (initializing) or re-enabling the interrupt, to clear
the EXTINT bit that could be set by changing the mode.

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Table 16. External Interrupt Mode register (EXTMODE - address 0xE01F C148) bit
description
Bit Symbol Value Description Reset
value
0 EXTMODE0 0 Level-sensitivity is selected for EINT0. 0
1 EINT0 is edge sensitive.
1 EXTMODE1 0 Level-sensitivity is selected for EINT1. 0
1 EINT1 is edge sensitive.
2 EXTMODE2 0 Level-sensitivity is selected for EINT2. 0
1 EINT2 is edge sensitive.
3 EXTMODE3 0 Level-sensitivity is selected for EINT3. 0
1 EINT3 is edge sensitive.
7:4 - - Reserved, user software should not write ones to reserved NA
bits. The value read from a reserved bit is not defined.

4.5.5 External Interrupt Polarity register (EXTPOLAR - 0xE01F C14C)

In level-sensitive mode, the bits in this register select whether the corresponding pin is
high- or low-active. In edge-sensitive mode, they select whether the pin is rising- or
falling-edge sensitive. Only pins that are selected for the EINT function (see "Pin Connect
Block" chapter) and enabled in the VICIntEnable register (Section 7.4.4 “Interrupt Enable
register (VICIntEnable - 0xFFFF F010)” on page 68) can cause interrupts from the
External Interrupt function (though of course pins selected for other functions may cause
interrupts from those functions).

Table 17. External Interrupt Polarity register (EXTPOLAR - address 0xE01F C14C) bit
description
Bit Symbol Value Description Reset
value
0 EXTPOLAR0 0 EINT0 is low-active or falling-edge sensitive (depending on 0
EXTMODE0 selection).
1 EINT0 is high-active or rising-edge sensitive (depending on
EXTMODE0 selection).
1 EXTPOLAR1 0 EINT1 is low-active or falling-edge sensitive (depending on 0
EXTMODE1 selection).
1 EINT1 is high-active or rising-edge sensitive (depending on
EXTMODE1 selection).
2 EXTPOLAR2 0 EINT2 is low-active or falling-edge sensitive (depending on 0
EXTMODE2 selection).
1 EINT2 is high-active or rising-edge sensitive (depending on
EXTMODE2 selection).

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Table 17. External Interrupt Polarity register (EXTPOLAR - address 0xE01F C14C) bit
description
Bit Symbol Value Description Reset
value
3 EXTPOLAR3 0 EINT3 is low-active or falling-edge sensitive (depending on 0
EXTMODE3 selection).
1 EINT3 is high-active or rising-edge sensitive (depending on
EXTMODE3 selection).
7:4 - - Reserved, user software should not write ones to reserved NA
bits. The value read from a reserved bit is not defined.

4.5.6 Multiple external interrupt pins

Software can select multiple pins for each of EINT3:0 in the Pin Select registers, which
are described in chapter Pin Connect Block on page 58. The external interrupt logic for
each of EINT3:0 receives the state of all of its associated pins from the pins’ receivers,
along with signals that indicate whether each pin is selected for the EINT function. The
external interrupt logic handles the case when more than one pin is so selected, differently
according to the state of its Mode and Polarity bits:

• In Low-Active Level Sensitive mode, the states of all pins selected for the same EINTx
functionality are digitally combined using a positive logic AND gate.
• In High-Active Level Sensitive mode, the states of all pins selected for the same
EINTx functionality are digitally combined using a positive logic OR gate.
• In Edge Sensitive mode, regardless of polarity, the pin with the lowest GPIO port
number is used. (Selecting multiple pins for an EINTx in edge-sensitive mode could
be considered a programming error.)

The signal derived by this logic is the EINTi signal in the following logic schematic
Figure 9.

For example, if the EINT3 function is selected in the PINSEL0 and PINSEL1 registers for
pins P0.9, P0.20 and P0.30, and EINT3 is configured to be low level sensitive, the inputs
from all three pins will be logically ANDed. When more than one EINT pin is logically
ORed, the interrupt service routine can read the states of the pins from the GPIO port
using the IO0PIN and IO1PIN registers, to determine which pin(s) caused the interrupt.

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wakeup enable
APB Read
(one bit of EXTWAKE)
of EXTWAKE

APB Bus Data D Q EINTi to wakeup

timer1

GLITCH
EINTi PCLK
FILTER

EXTPOLARi interrupt flag

(one bit of EXTINT)

1 S
D S S

Q Q Q to VIC

R R
EXTMODEi
APB read of
EXTINT
PCLK PCLK

reset
write 1 to EXTINTi

(1) See Figure 11 “Reset block diagram including the wakeup timer”
Fig 9. External interrupt logic

4.6 Other system controls

Some aspects of controlling LPC213x/01 operation that do not fit into peripheral or other
registers are grouped here.

4.6.1 System Control and Status flags register (SCS - 0xE01F C1A0)
Table 18. System Control and Status flags register (SCS - address 0xE01F C1A0) bit description
Bit Symbol Value Description Reset
value
0 GPIO0M GPIO port 0 mode selection. 0
0 GPIO port 0 is accessed via APB addresses in a fashion compatible with previous
LCP2000 devices.
1 High speed GPIO is enabled on GPIO port 0, accessed via addresses in the on-chip
memory range. This mode includes the port masking feature described in the GPIO
chapter on page page 79.

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Table 18. System Control and Status flags register (SCS - address 0xE01F C1A0) bit description
Bit Symbol Value Description Reset
value
1 GPIO1M GPIO port 1 mode selection. 0
0 GPIO port 1 is accessed via APB addresses in a fashion compatible with previous
LCP2000 devices.
1 High speed GPIO is enabled on GPIO port 1, accessed via addresses in the on-chip
memory range. This mode includes the port masking feature described in the GPIO
chapter on page page 79.
31:2 - Reserved, user software should not write ones to reserved bits. The value read from a NA
reserved bit is not defined.

4.7 Memory mapping control

The Memory Mapping Control alters the mapping of the interrupt vectors that appear
beginning at address 0x0000 0000. This allows code running in different memory spaces
to have control of the interrupts.

4.7.1 Memory Mapping control register (MEMMAP - 0xE01F C040)

Whenever an exception handling is necessary, the microcontroller will fetch an instruction
residing on the exception corresponding address as described in Table 3 “ARM exception
vector locations” on page 13. The MEMMAP register determines the source of data that
will fill this table.

Table 19. Memory Mapping control register (MEMMAP - address 0xE01F C040) bit
description
Bit Symbol Value Description Reset
value
1:0 MAP 00 Boot Loader Mode. Interrupt vectors are re-mapped to Boot 00
Block.
01 User Flash Mode. Interrupt vectors are not re-mapped and
reside in Flash.
10 User RAM Mode. Interrupt vectors are re-mapped to Static
RAM.
11 Reserved. Do not use this option.
Warning: Improper setting of this value may result in incorrect
operation of the device.
7:2 - - Reserved, user software should not write ones to reserved NA
bits. The value read from a reserved bit is not defined.

4.7.2 Memory mapping control usage notes

The Memory Mapping Control simply selects one out of three available sources of data
(sets of 64 bytes each) necessary for handling ARM exceptions (interrupts).

For example, whenever a Software Interrupt request is generated, the ARM core will
always fetch 32-bit data "residing" on 0x0000 0008 see Table 3 “ARM exception vector
locations” on page 13. This means that when MEMMAP[1:0]=10 (User RAM Mode), a

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read/fetch from 0x0000 0008 will provide data stored in 0x4000 0008. In case of
MEMMAP[1:0]=00 (Boot Loader Mode), a read/fetch from 0x0000 0008 will provide data
available also at 0x7FFF E008 (Boot Block remapped from on-chip Bootloader).

4.8 Phase Locked Loop (PLL)

The PLL accepts an input clock frequency in the range of 10 MHz to 25 MHz only. The
input frequency is multiplied up into the CCLK with the range of 10 MHz to 60 MHz using
a Current Controlled Oscillator (CCO). The multiplier can be an integer value from 1 to 32
(in practice, the multiplier value cannot be higher than 6 on the LPC213x due to the upper
frequency limit of the CPU). The CCO operates in the range of 156 MHz to 320 MHz, so
there is an additional divider in the loop to keep the CCO within its frequency range while
the PLL is providing the desired output frequency. The output divider may be set to divide
by 2, 4, 8, or 16 to produce the output clock. Since the minimum output divider value is 2,
it is insured that the PLL output has a 50% duty cycle. A block diagram of the PLL is
shown in Figure 10.

PLL activation is controlled via the PLLCON register. The PLL multiplier and divider
values are controlled by the PLLCFG register. These two registers are protected in order
to prevent accidental alteration of PLL parameters or deactivation of the PLL. Since all
chip operations, including the Watchdog Timer, are dependent on the PLL when it is
providing the chip clock, accidental changes to the PLL setup could result in unexpected
behavior of the microcontroller. The protection is accomplished by a feed sequence
similar to that of the Watchdog Timer. Details are provided in the description of the
PLLFEED register.

The PLL is turned off and bypassed following a chip Reset and when by entering
Power-down mode. The PLL is enabled by software only. The program must configure
and activate the PLL, wait for the PLL to Lock, then connect to the PLL as a clock source.

4.8.1 Register description

The PLL is controlled by the registers shown in Table 20. More detailed descriptions
follow.

Warning: Improper setting of the PLL values may result in incorrect operation of the
device!

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Table 20. PLL registers

Name Description Access Reset Address
value[1]
PLLCON PLL Control Register. Holding register for R/W 0 0xE01F C080
updating PLL control bits. Values written to this
register do not take effect until a valid PLL feed
sequence has taken place.
PLLCFG PLL Configuration Register. Holding register for R/W 0 0xE01F C084
updating PLL configuration values. Values
written to this register do not take effect until a
valid PLL feed sequence has taken place.
PLLSTAT PLL Status Register. Read-back register for RO 0 0xE01F C088
PLL control and configuration information. If
PLLCON or PLLCFG have been written to, but
a PLL feed sequence has not yet occurred, they
will not reflect the current PLL state. Reading
this register provides the actual values
controlling the PLL, as well as the status of the
PLL.
PLLFEED PLL Feed Register. This register enables WO NA 0xE01F C08C
loading of the PLL control and configuration
information from the PLLCON and PLLCFG
registers into the shadow registers that actually
affect PLL operation.

[1] Reset value reflects the data stored in used bits only. It does not include reserved bits content.

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PLLC
CLOCK
SYNCHRONIZATION

0 direct

PSEL[1:0]

PD PD

PLLE
0 bypass

FOSC 1 CD
PHASE- FCCO
FREQUENCY CCO 0
0
PLOCK DETECTOR /2P
0 CCLK
1
PD 1

CD
FOUT

DIV-BY-M

MSEL<4:0>
MSEL[4:0]

Fig 10. PLL block diagram

4.8.2 PLL Control register (PLLCON - 0xE01F C080)

The PLLCON register contains the bits that enable and connect the PLL. Enabling the
PLL allows it to attempt to lock to the current settings of the multiplier and divider values.
Connecting the PLL causes the processor and all chip functions to run from the PLL
output clock. Changes to the PLLCON register do not take effect until a correct PLL feed
sequence has been given (see Section 4.8.7 “PLL Feed register (PLLFEED -
0xE01F C08C)” and Section 4.8.3 “PLL Configuration register (PLLCFG - 0xE01F C084)”
on page 36).

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Table 21. PLL Control register (PLLCON - address 0xE01F C080) bit description
Bit Symbol Description Reset
value
0 PLLE PLL Enable. When one, and after a valid PLL feed, this bit will 0
activate the PLL and allow it to lock to the requested frequency. See
PLLSTAT register, Table 23.
1 PLLC PLL Connect. When PLLC and PLLE are both set to one, and after a 0
valid PLL feed, connects the PLL as the clock source for the
microcontroller. Otherwise, the oscillator clock is used directly by the
microcontroller. See PLLSTAT register, Table 23.
7:2 - Reserved, user software should not write ones to reserved bits. The NA
value read from a reserved bit is not defined.

The PLL must be set up, enabled, and Lock established before it may be used as a clock
source. When switching from the oscillator clock to the PLL output or vice versa, internal
circuitry synchronizes the operation in order to ensure that glitches are not generated.
Hardware does not insure that the PLL is locked before it is connected or automatically
disconnect the PLL if lock is lost during operation. In the event of loss of PLL lock, it is
likely that the oscillator clock has become unstable and disconnecting the PLL will not
remedy the situation.

4.8.3 PLL Configuration register (PLLCFG - 0xE01F C084)

The PLLCFG register contains the PLL multiplier and divider values. Changes to the
PLLCFG register do not take effect until a correct PLL feed sequence has been given (see
Section 4.8.7 “PLL Feed register (PLLFEED - 0xE01F C08C)” on page 37). Calculations
for the PLL frequency, and multiplier and divider values are found in the PLL Frequency
Calculation section on page 38.

Table 22. PLL Configuration register (PLLCFG - address 0xE01F C084) bit description
Bit Symbol Description Reset
value
4:0 MSEL PLL Multiplier value. Supplies the value "M" in the PLL frequency 0
calculations.
Note: For details on selecting the right value for MSEL see
Section 4.8.9 “PLL frequency calculation” on page 38.
6:5 PSEL PLL Divider value. Supplies the value "P" in the PLL frequency 0
calculations.
Note: For details on selecting the right value for PSEL see
Section 4.8.9 “PLL frequency calculation” on page 38.
7 - Reserved, user software should not write ones to reserved bits. The NA
value read from a reserved bit is not defined.

4.8.4 PLL Status register (PLLSTAT - 0xE01F C088)

The read-only PLLSTAT register provides the actual PLL parameters that are in effect at
the time it is read, as well as the PLL status. PLLSTAT may disagree with values found in
PLLCON and PLLCFG because changes to those registers do not take effect until a
proper PLL feed has occurred (see Section 4.8.7 “PLL Feed register (PLLFEED -
0xE01F C08C)”).

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Table 23. PLL Status register (PLLSTAT - address 0xE01F C088) bit description
Bit Symbol Description Reset
value
4:0 MSEL Read-back for the PLL Multiplier value. This is the value currently 0
used by the PLL.
6:5 PSEL Read-back for the PLL Divider value. This is the value currently 0
used by the PLL.
7 - Reserved, user software should not write ones to reserved bits. The NA
value read from a reserved bit is not defined.
8 PLLE Read-back for the PLL Enable bit. When one, the PLL is currently 0
activated. When zero, the PLL is turned off. This bit is automatically
cleared when Power-down mode is activated.
9 PLLC Read-back for the PLL Connect bit. When PLLC and PLLE are both 0
one, the PLL is connected as the clock source for the
microcontroller. When either PLLC or PLLE is zero, the PLL is
bypassed and the oscillator clock is used directly by the
microcontroller. This bit is automatically cleared when Power-down
mode is activated.
10 PLOCK Reflects the PLL Lock status. When zero, the PLL is not locked. 0
When one, the PLL is locked onto the requested frequency.
15:11 - Reserved, user software should not write ones to reserved bits. The NA
value read from a reserved bit is not defined.

4.8.5 PLL Interrupt

The PLOCK bit in the PLLSTAT register is connected to the interrupt controller. This
allows for software to turn on the PLL and continue with other functions without having to
wait for the PLL to achieve lock. When the interrupt occurs (PLOCK = 1), the PLL may be
connected, and the interrupt disabled.

4.8.6 PLL Modes

The combinations of PLLE and PLLC are shown in Table 24.

Table 24. PLL Control bit combinations

PLLC PLLE PLL Function
0 0 PLL is turned off and disconnected. The system runs from the unmodified clock
input.
0 1 The PLL is active, but not yet connected. The PLL can be connected after
PLOCK is asserted.
1 0 Same as 00 combination. This prevents the possibility of the PLL being
connected without also being enabled.
1 1 The PLL is active and has been connected as the system clock source.

4.8.7 PLL Feed register (PLLFEED - 0xE01F C08C)

A correct feed sequence must be written to the PLLFEED register in order for changes to
the PLLCON and PLLCFG registers to take effect. The feed sequence is:

1. Write the value 0xAA to PLLFEED.

2. Write the value 0x55 to PLLFEED.

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The two writes must be in the correct sequence, and must be consecutive APB bus
cycles. The latter requirement implies that interrupts must be disabled for the duration of
the PLL feed operation. If either of the feed values is incorrect, or one of the previously
mentioned conditions is not met, any changes to the PLLCON or PLLCFG register will not
become effective.

Table 25. PLL Feed register (PLLFEED - address 0xE01F C08C) bit description
Bit Symbol Description Reset
value
7:0 PLLFEED The PLL feed sequence must be written to this register in order for 0x00
PLL configuration and control register changes to take effect.

4.8.8 PLL and Power-down mode

Power-down mode automatically turns off and disconnects the PLL. Wake-up from
Power-down mode does not automatically restore the PLL settings, this must be done in
software. Typically, a routine to activate the PLL, wait for lock, and then connect the PLL
can be called at the beginning of any interrupt service routine that might be called due to
the wake-up. It is important not to attempt to restart the PLL by simply feeding it when
execution resumes after a wake-up from Power-down mode. This would enable and
connect the PLL at the same time, before PLL lock is established.

4.8.9 PLL frequency calculation

The PLL equations use the following parameters:

Table 26. Elements determining PLL’s frequency

Element Description
FOSC the frequency from the crystal oscillator/external oscillator
FCCO the frequency of the PLL current controlled oscillator
CCLK the PLL output frequency (also the processor clock frequency)
M PLL Multiplier value from the MSEL bits in the PLLCFG register
P PLL Divider value from the PSEL bits in the PLLCFG register

The PLL output frequency (when the PLL is both active and connected) is given by:

CCLK = M × FOSC or CCLK = FCCO / (2 × P)

The CCO frequency can be computed as:

FCCO = CCLK × 2 × P or FCCO = FOSC × M × 2 × P

The PLL inputs and settings must meet the following:

• FOSC is in the range of 10 MHz to 25 MHz.

• CCLK is in the range of 10 MHz to Fmax (the maximum allowed frequency for the
microcontroller - determined by the system microcontroller is embedded in).
• FCCO is in the range of 156 MHz to 320 MHz.

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4.8.10 Procedure for determining PLL settings

If a particular application uses the PLL, its configuration may be determined as follows:

1. Choose the desired processor operating frequency (CCLK). This may be based on
processor throughput requirements, need to support a specific set of UART baud
rates, etc. Bear in mind that peripheral devices may be running from a lower clock
than the processor (see Section 4.11 “APB divider” on page 45).
2. Choose an oscillator frequency (FOSC). CCLK must be the whole (non-fractional)
multiple of FOSC.
3. Calculate the value of M to configure the MSEL bits. M = CCLK / FOSC. M must be in
the range of 1 to 32. The value written to the MSEL bits in PLLCFG is M − 1 (see
Table 28.
4. Find a value for P to configure the PSEL bits, such that FCCO is within its defined
frequency limits. FCCO is calculated using the equation given above. P must have one
of the values 1, 2, 4, or 8. The value written to the PSEL bits in PLLCFG is 00 for
P = 1; 01 for P = 2; 10 for P = 4; 11 for P = 8 (see Table 27).

Table 27. PLL Divider values

PSEL Bits (PLLCFG bits [6:5]) Value of P
00 1
01 2
10 4
11 8

Table 28. PLL Multiplier values

MSEL Bits (PLLCFG bits [4:0]) Value of M
00000 1
00001 2
00010 3
00011 4
... ...
11110 31
11111 32

4.8.11 PLL example

System design asks for FOSC= 10 MHz and requires CCLK = 60 MHz.

Based on these specifications, M = CCLK / Fosc = 60 MHz / 10 MHz = 6. Consequently,

M - 1 = 5 will be written as PLLCFG[4:0].

Value for P can be derived from P = FCCO / (CCLK x 2), using condition that FCCO must be
in range of 156 MHz to 320 MHz. Assuming the lowest allowed frequency for
FCCO = 156 MHz, P = 156 MHz / (2 x 60 MHz) = 1.3. The highest FCCO frequency criteria
produces P = 2.67. The only solution for P that satisfies both of these requirements and is
listed in Table 27 is P = 2. Therefore, PLLCFG[6:5] = 1 will be used.

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4.9 Power control

The LPC213x supports two reduced power modes: Idle mode and Power-down mode. In
Idle mode, execution of instructions is suspended until either a Reset or interrupt occurs.
Peripheral functions continue operation during Idle mode and may generate interrupts to
cause the processor to resume execution. Idle mode eliminates power used by the
processor itself, memory systems and related controllers, and internal buses.

In Power-down mode, the oscillator is shut down and the chip receives no internal clocks.
The processor state and registers, peripheral registers, and internal SRAM values are
preserved throughout Power-down mode and the logic levels of chip pins remain static.
The Power-down mode can be terminated and normal operation resumed by either a
Reset or certain specific interrupts that are able to function without clocks. Since all
dynamic operation of the chip is suspended, Power-down mode reduces chip power
consumption to nearly zero.

Entry to Power-down and Idle modes must be coordinated with program execution.
Wake-up from Power-down or Idle modes via an interrupt resumes program execution in
such a way that no instructions are lost, incomplete, or repeated. Wake up from
Power-down mode is discussed further in Section 4.12 “Wake-up timer” on page 46.

A Power Control for Peripherals feature allows individual peripherals to be turned off if
they are not needed in the application, resulting in additional power savings.

4.9.1 Register description

The Power Control function contains two registers, as shown in Table 29. More detailed
descriptions follow.

Table 29. Power control registers

Name Description Access Reset Address
value[1]
PCON Power Control Register. This register contains R/W 0x00 0xE01F C0C0
control bits that enable the two reduced power
operating modes of the microcontroller. See
Table 30.
PCONP Power Control for Peripherals Register. This R/W 0x0008 17BE 0xE01F C0C4
register contains control bits that enable and
disable individual peripheral functions,
Allowing elimination of power consumption by
peripherals that are not needed.

[1] Reset value reflects the data stored in used bits only. It does not include reserved bits content.

4.9.2 Power Control register (PCON - 0xE01F C0C0)

The PCON register contains two bits. Writing a one to the corresponding bit causes entry
to either the Power-down or Idle mode. If both bits are set, Power-down mode is entered.

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Table 30. Power Control register (PCON - address 0xE01F C0C0) bit description
Bit Symbol Value Description Reset
value
0 IDL Idle mode control. 0
0 Idle mode is off.
1 The processor clock is stopped, while on-chip peripherals remain
active. Any enabled interrupt from a peripheral or an external
interrupt source will cause the processor to resume execution.
1 PD Power-down mode control. 0
0 Power-down mode is off.
1 The oscillator and all on-chip clocks are stopped. A wakeup
condition from an external interrupt can cause the oscillator to
restart, the PD bit to be cleared, and the processor to resume
execution.
2 BODPDM Brown Out Power-down Mode. 0
0 Brown Out Detection (BOD) remains operative during
Power-down mode, and its Reset can release the microcontroller
from Power-down mode[1].
1 The BOD circuitry will go into power down mode when PD = 1,
resulting in a further reduction in power. In this case the BOD can
not be used as a wakeup source from Power Down mode.
3 BOGD[2] Brown Out Global Disable. 0
0 The BOD circuitry is enabled.
1 The BOD is fully disabled at all times, consuming no power.
4 BORD[2] Brown Out Reset Disable. 0
0 The reset is enabled. The first stage of low voltage detection
(2.9 V) Brown Out interrupt is not affected.
1 The second stage of low voltage detection (2.6 V) will not cause
a chip reset.
7:5 - Reserved, user software should not write ones to reserved bits. NA
The value read from a reserved bit is not defined.

[1] Since execution is delayed until after the Wake-up Timer has allowed the main oscillator to resume stable
operation, there is no guarantee that execution will resume before VDD has fallen below the lower BOD
threshold, which prevents execution. If execution does resume, there is no guarantee of how long the
microcontroller will continue execution before the lower BOD threshold terminates execution. These issues
depend on the slope of the decline of VDD. High decoupling capacitance (between VDD and ground) in the
vicinity of the microcontroller will improve the likelihood that software will be able to do what needs to be
done when power is being lost.
[2] This feature is available in LPC213x/01 only.

4.9.3 Power Control for Peripherals register (PCONP - 0xE01F C0C4)

The PCONP register allows turning off selected peripheral functions for the purpose of
saving power. This is accomplished by gating off the clock source to the specified
peripheral blocks. A few peripheral functions cannot be turned off (i.e. the Watchdog timer,
GPIO, the Pin Connect block, and the System Control block). Some peripherals,
particularly those that include analog functions, may consume power that is not clock
dependent. These peripherals may contain a separate disable control that turns off
additional circuitry to reduce power. Each bit in PCONP controls one of the peripherals.

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The bit numbers correspond to the related peripheral number as shown in the APB
peripheral map Figure 4 “AHB peripheral map” in the "LPC2131/2/4/6/8 Memory
Addressing" chapter.

If a peripheral control bit is 1, that peripheral is enabled. If a peripheral bit is 0, that

peripheral is disabled to conserve power. For example if bit 19 is 1, the I2C1 interface is
enabled. If bit 19 is 0, the I2C1 interface is disabled.

Important: valid read from a peripheral register and valid write to a peripheral
register is possible only if that peripheral is enabled in the PCONP register!

Table 31. Power Control for Peripherals register (PCONP - address 0xE01F C0C4) bit
description
Bit Symbol Description Reset
value
0 - Reserved, user software should not write ones to reserved bits. The NA
value read from a reserved bit is not defined.
1 PCTIM0 Timer/Counter 0 power/clock control bit. 1
2 PCTIM1 Timer/Counter 1 power/clock control bit. 1
3 PCUART0 UART0 power/clock control bit. 1
4 PCUART1 UART1 power/clock control bit. 1
5 PCPWM0 PWM0 power/clock control bit. 1
6 - Reserved, user software should not write ones to reserved bits. The NA
value read from a reserved bit is not defined.
7 PCI2C0 The I2C0 interface power/clock control bit. 1
8 PCSPI0 The SPI0 interface power/clock control bit. 1
9 PCRTC The RTC power/clock control bit. 1
10 PCSPI1 The SSP interface power/clock control bit. 1
11 - Reserved, user software should not write ones to reserved bits. The NA
value read from a reserved bit is not defined.
12 PCAD0 A/D converter 0 (ADC0) power/clock control bit. 1
Note: Clear the PDN bit in the AD0CR before clearing this bit, and set
this bit before setting PDN.
18:13 - Reserved, user software should not write ones to reserved bits. The NA
value read from a reserved bit is not defined.
19 PCI2C1 The I2C1 interface power/clock control bit. 1
20 PCAD1 A/D converter 1 (ADC1) power/clock control bit. 0
Note: Clear the PDN bit in the AD1CR before clearing this bit, and set
this bit before setting PDN.
31:21 - Reserved, user software should not write ones to reserved bits. The NA
value read from a reserved bit is not defined.

4.9.4 Power control usage notes

After every reset, the PCONP register contains the value that enables all interfaces and
peripherals controlled by the PCONP to be enabled. Therefore, apart from proper
configuring via peripheral dedicated registers, the user’s application has no need to
access the PCONP in order to start using any of the on-board peripherals.

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Power saving oriented systems should have 1s in the PCONP register only in positions
that match peripherals really used in the application. All other bits, declared to be
"Reserved" or dedicated to the peripherals not used in the current application, must be
cleared to 0.

4.10 Reset
Reset has three sources on the LPC213x: the RESET pin, Watchdog Reset and
Brown-Out-Detector (BOD) Reset. The RESET pin is a Schmitt trigger input pin with an
additional glitch filter. Assertion of chip Reset by any source starts the Wake-up Timer
(see description in Section 4.12 “Wake-up timer” in this chapter), causing reset to remain
asserted until the external Reset is de-asserted, the oscillator is running, a fixed number
of clocks have passed, and the on-chip circuitry has completed its initialization. The
relationship between Reset, the oscillator, and the Wake-up Timer are shown in Figure 11.

The Reset glitch filter allows the processor to ignore external reset pulses that are very
short, and also determines the minimum duration of RESET that must be asserted in
order to guarantee a chip reset. Once asserted, RESET pin can be deasserted only when
crystal oscillator is fully running and an adequate signal is present on the X1 pin of the
microcontroller. Assuming that an external crystal is used in the crystal oscillator
subsystem, after power on, the RESET pin should be asserted for 10 ms. For all
subsequent resets when crystal oscillator is already running and stable signal is on the X1
pin, the RESET pin needs to be asserted for 300 ns only.

When the internal Reset is removed, the processor begins executing at address 0, which
is initially the Reset vector mapped from the Boot Block. At that point, all of the processor
and peripheral registers have been initialized to predetermined values.

External and internal Resets have some small differences. An external Reset causes the
value of certain pins to be latched to configure the part. External circuitry cannot
determine when an internal Reset occurs in order to allow setting up those special pins,
so those latches are not reloaded during an internal Reset. Pins that are examined during
an external Reset for various purposes are: P1.20/TRACESYNC, P1.26/RTCK (see
chapters "Pin Configuration" and "Pin Connect Block" ). Pin P0.14 (see "Flash Memory
System and Programming" chapter) is examined by on-chip bootloader when this code is
executed after every Reset.

It is possible for a chip Reset to occur during a Flash programming or erase operation.
The Flash memory will interrupt the ongoing operation and hold off the completion of
Reset to the CPU until internal Flash high voltages have settled.

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external Reset to the

C on-chip circuitry
reset
Q

watchdog S Reset to
reset PCON.PD

WAKEUP TIMER

START
power
down
COUNT 2n C

EINT0 wakeup oscillator Q

EINT1 wakeup
EINT2 wakeup output (FOSC) S
EINT3 wakeup
RTC wakeup write “1”
BOD wakeup from APB

reset

ABP read of
PDBIT
in PCON

FOSC
to other blocks

Fig 11. Reset block diagram including the wakeup timer

4.10.1 Reset Source Identification Register (RSIR - 0xE01F C180)

This register contains one bit for each source of Reset. Writing a 1 to any of these bits
clears the corresponding read-side bit to 0. The interactions among the four sources are
described below.

Table 32. Reset Source Identification Register (RSIR - address 0xE01F C180) bit description
Bit Symbol Description Reset
value
0 POR Assertion of the POR signal sets this bit, and clears all of the other bits in see text
this register. But if another Reset signal (e.g., External Reset) remains
asserted after the POR signal is negated, then its bit is set. This bit is not
affected by any of the other sources of Reset.
1 EXTR Assertion of the RESET signal sets this bit. This bit is cleared by POR, see text
but is not affected by WDT or BOD reset.

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Table 32. Reset Source Identification Register (RSIR - address 0xE01F C180) bit description
Bit Symbol Description Reset
value
2 WDTR This bit is set when the Watchdog Timer times out and the WDTRESET see text
bit in the Watchdog Mode Register is 1. It is cleared by any of the other
sources of Reset.
3 BODR This bit is set when the 3.3 V power reaches a level below 2.6 V. If the see text
VDD voltage dips from 3.3 V to 2.5 V and backs up, the BODR bit will be
set to 1. Also, if the VDD voltage rises continuously from below 1 V to a
level above 2.6 V, the BODR will be set to 1, too. This bit is not affected
by External Reset nor Watchdog Reset.
Note: only in case a reset occurs and the POR = 0, the BODR bit
indicates if the VDD voltage was below 2.6 V or not.
7:4 - Reserved, user software should not write ones to reserved bits. The NA
value read from a reserved bit is not defined.

4.11 APB divider

The APB Divider determines the relationship between the processor clock (CCLK) and the
clock used by peripheral devices (PCLK). The APB Divider serves two purposes. The first
is to provides peripherals with desired PCLK via APB bus so that they can operate at the
speed chosen for the ARM processor. In order to achieve this, the APB bus may be
slowed down to one half or one fourth of the processor clock rate. Because the APB bus
must work properly at power up (and its timing cannot be altered if it does not work since
the APB divider control registers reside on the APB bus), the default condition at reset is
for the APB bus to run at one quarter speed. The second purpose of the APB Divider is to
allow power savings when an application does not require any peripherals to run at the full
processor rate.

The connection of the APB Divider relative to the oscillator and the processor clock is
shown in Figure 12. Because the APB Divider is connected to the PLL output, the PLL
remains active (if it was running) during Idle mode.

4.11.1 Register description

Only one register is used to control the APB Divider.

Table 33. APB divider register map

Name Description Access Reset Address
value[1]
APBDIV Controls the rate of the APB clock in relation to R/W 0x00 0xE01F C100
the processor clock.

[1] Reset value reflects the data stored in used bits only. It does not include reserved bits content.

4.11.2 APBDIV register (APBDIV - 0xE01F C100)

The APB Divider register contains two bits, allowing three divider values, as shown in
Table 34.

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Table 34. APB Divider register (APBDIV - address 0xE01F C100) bit description
Bit Symbol Value Description Reset
value
1:0 APBDIV 00 APB bus clock is one fourth of the processor clock. 00
01 APB bus clock is the same as the processor clock.
10 APB bus clock is one half of the processor clock.
11 Reserved. If this value is written to the APBDIV register, it
has no effect (the previous setting is retained).
7:2 - - Reserved, user software should not write ones to reserved NA
bits. The value read from a reserved bit is not defined.

crystal oscillator or
processor clock
external clock source PLL0
(CCLK)
(FOSC)

APB clock
APB DIVIDER
(PCLK)

Fig 12. APB divider connections

4.12 Wake-up timer

The purpose of the wake-up timer is to ensure that the oscillator and other analog
functions required for chip operation are fully functional before the processor is allowed to
execute instructions. This is important at power on, all types of Reset, and whenever any
of the aforementioned functions are turned off for any reason. Since the oscillator and
other functions are turned off during Power-down mode, any wake-up of the processor
from Power-down mode makes use of the Wake-up Timer.

The Wake-up Timer monitors the crystal oscillator as the means of checking whether it is
safe to begin code execution. When power is applied to the chip, or some event caused
the chip to exit Power-down mode, some time is required for the oscillator to produce a
signal of sufficient amplitude to drive the clock logic. The amount of time depends on
many factors, including the rate of VDD ramp (in the case of power on), the type of crystal
and its electrical characteristics (if a quartz crystal is used), as well as any other external
circuitry (e.g. capacitors), and the characteristics of the oscillator itself under the existing
ambient conditions.

Once a clock is detected, the Wake-up Timer counts 4096 clocks, then enables the
on-chip circuitry to initialize. When the onboard modules initialization is complete, the
processor is released to execute instructions if the external Reset has been deasserted.
In the case where an external clock source is used in the system (as opposed to a crystal
connected to the oscillator pins), the possibility that there could be little or no delay for

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oscillator start-up must be considered. The Wake-up Timer design then ensures that any
other required chip functions will be operational prior to the beginning of program
execution.

Any of the various Resets can bring the microcontroller out of power-down mode, as can
the external interrupts EINT3:0, plus the RTC interrupt if the RTC is operating from its own
oscillator on the RTCX1-2 pins. When one of these interrupts is enabled for wake-up and
its selected event occurs, an oscillator wake-up cycle is started. The actual interrupt (if
any) occurs after the wake-up timer expires, and is handled by the Vectored Interrupt
Controller.

However, the pin multiplexing on the LPC213x (see chapters "Pin Configuration" and "Pin
Connect Block") was designed to allow other peripherals to, in effect, bring the device out
of Power-down mode. The following pin-function pairings allow interrupts from events
relating to UART0 or 1, SPI 0 or 1, or the I2C: RxD0 / EINT0, SDA / EINT1, SSEL0 /
EINT2, RxD1 / EINT3, DCD1 / EINT1, RI1 / EINT2, SSEL1 / EINT3.

To put the device in Power-down mode and allow activity on one or more of these buses
or lines to power it back up, software should reprogram the pin function to External
Interrupt, select the appropriate mode and polarity for the Interrupt, and then select
Power-down mode. Upon wake-up software should restore the pin multiplexing to the
peripheral function.

All of the bus- or line-activity indications in the list above happen to be low-active. If
software wants the device to come out of power -down mode in response to activity on
more than one pin that share the same EINTi channel, it should program low-level
sensitivity for that channel, because only in level mode will the channel logically OR the
signals to wake the device.

The only flaw in this scheme is that the time to restart the oscillator prevents the LPC213x
from capturing the bus or line activity that wakes it up. Idle mode is more appropriate than
power-down mode for devices that must capture and respond to external activity in a
timely manner.

To summarize: on the LPC213x, the Wake-up Timer enforces a minimum reset duration
based on the crystal oscillator, and is activated whenever there is a wake-up from
Power-down mode or any type of Reset.

4.13 Brown-out detection

The LPC213x includes 2-stage monitoring of the voltage on the VDD pins. If this voltage
falls below 2.9 V, the Brown-Out Detector (BOD) asserts an interrupt signal to the
Vectored Interrupt Controller. This signal can be enabled for interrupt in the Interrupt
Enable register (see Section 7.4.4 “Interrupt Enable register (VICIntEnable -
0xFFFF F010)” on page 68); if not, software can monitor the signal by reading the Raw
Interrupt Status register (see Section 7.4.3 “Raw Interrupt status register (VICRawIntr -
0xFFFF F008)” on page 68).

The second stage of low-voltage detection asserts Reset to inactivate the LPC213x when
the voltage on the VDD pins falls below 2.6 V. This Reset prevents alteration of the Flash
as operation of the various elements of the chip would otherwise become unreliable due
to low voltage. The BOD circuit maintains this reset down below 1 V, at which point the
Power-On Reset circuitry maintains the overall Reset.
UM10120 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved.

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Both the 2.9 V and 2.6 V thresholds include some hysteresis. In normal operation, this
hysteresis allows the 2.9 V detection to reliably interrupt, or a regularly-executed event
loop to sense the condition.

But when Brown-Out Detection is enabled to bring the LPC213x out of Power-Down mode
(which is itself not a guaranteed operation -- see Section 4.9.2 “Power Control register
(PCON - 0xE01F C0C0)”), the supply voltage may recover from a transient before the
Wake-up Timer has completed its delay. In this case, the net result of the transient BOD is
that the part wakes up and continues operation after the instructions that set Power-Down
Mode, without any interrupt occurring and with the BOD bit in the RISR being 0. Since all
other wake-up conditions have latching flags (see Section 4.5.2 “External Interrupt Flag
register (EXTINT - 0xE01F C140)” and Section 17.4.3 “Interrupt Location Register (ILR -
0xE002 4000)” on page 220), a wake-up of this type, without any apparent cause, can be
assumed to be a Brown-Out that has gone away.

4.14 Code security vs debugging

Applications in development typically need the debugging and tracing facilities in the
LPC213x. Later in the life cycle of an application, it may be more important to protect the
application code from observation by hostile or competitive eyes. The following feature of
the LPC213x allows an application to control whether it can be debugged or protected
from observation.

Details on the way Code Read Protection works can be found in the "Flash Memory
System and Programming" chapter.

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Chapter 5: LPC213x Pin configuration
Rev. 3 — 4 October 2010 User manual

5.1 LPC213x pinout

54 P0.19/MAT1.2/MOSI1/CAP1.2
53 P0.18/CAP1.3/MISO1/MAT1.3
55 P0.20/MAT1.3/SSEL1/EINT3
64 P1.27/TDO

52 P1.30/TMS
56 P1.29/TCK
60 P1.28/TDI

57 RESET
62 XTAL1
61 XTAL2
63 VREF

58 P0.23

49 VBAT
59 VSSA

51 VDD
50 VSS
P0.21/PWM5/CAP1.3 1 48 P1.20/TRACESYNC
P0.22/CAP0.0/MAT0.0 2 47 P0.17/CAP1.2/SCK1/MAT1.2
RTCX1 3 46 P0.16/EINT0/MAT0.2/CAP0.2
P1.19/TRACEPKT3 4 45 P0.15/EINT2
RTCX2 5 44 P1.21/PIPESTAT0
VSS 6 43 VDD
VDDA 7 42 VSS
P1.18/TRACEPKT2 8 41 P0.14/EINT1/SDA1
LPC2131
P0.25/AD0.4 9 40 P1.22/PIPESTAT1
LPC2131/01
P0.26/AD0.5 10 39 P0.13/MAT1.1
P0.27/AD0.0/CAP0.1/MAT0.1 11 38 P0.12/MAT1.0
P1.17/TRACEPKT1 12 37 P0.11/CAP1.1/SCL1
P0.28/AD0.1/CAP0.2/MAT0.2 13 36 P1.23/PIPESTAT2
P0.29/AD0.2/CAP0.3/MAT0.3 14 35 P0.10/CAP1.0
P0.30/AD0.3/EINT3/CAP0.0 15 34 P0.9/RXD1/PWM6/EINT3
P1.16/TRACEPKT0 16 33 P0.8/TXD1/PWM4
P0.31 17
VSS 18
P0.0/TXD0/PWM1 19
P1.31/TRST 20
P0.1/RXD0/PWM3/EINT0 21
P0.2/SCL0/CAP0.0 22
VDD 23
P1.26/RTCK 24
VSS 25
P0.3/SDA0/MAT0.0/EINT1 26
P0.4/SCK0/CAP0.1/AD0.6 27
P1.25/EXTIN0 28
P0.5/MISO0/MAT0.1/AD0.7 29
P0.6/MOSI0/CAP0.2 30
P0.7/SSEL0/PWM2/EINT2 31
P1.24/TRACECLK 32

002aab068

Fig 13. LPC2131 and LPC2131/01 64-pin package

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54 P0.19/MAT1.2/MOSI1/CAP1.2
53 P0.18/CAP1.3/MISO1/MAT1.3
55 P0.20/MAT1.3/SSEL1/EINT3
64 P1.27/TDO

52 P1.30/TMS
56 P1.29/TCK
60 P1.28/TDI

57 RESET
62 XTAL1
61 XTAL2
63 VREF

58 P0.23

49 VBAT
59 VSSA

51 VDD
50 VSS
P0.21/PWM5/CAP1.3 1 48 P1.20/TRACESYNC
P0.22/CAP0.0/MAT0.0 2 47 P0.17/CAP1.2/SCK1/MAT1.2
RTCX1 3 46 P0.16/EINT0/MAT0.2/CAP0.2
P1.19/TRACEPKT3 4 45 P0.15/EINT2
RTCX2 5 44 P1.21/PIPESTAT0
VSS 6 43 VDD
VDDA 7 42 VSS
P1.18/TRACEPKT2 8 41 P0.14/EINT1/SDA1
LPC2132
P0.25/AD0.4/AOUT 9 40 P1.22/PIPESTAT1
LPC2132/01
P0.26/AD0.5 10 39 P0.13/MAT1.1
P0.27/AD0.0/CAP0.1/MAT0.1 11 38 P0.12/MAT1.0
P1.17/TRACEPKT1 12 37 P0.11/CAP1.1/SCL1
P0.28/AD0.1/CAP0.2/MAT0.2 13 36 P1.23/PIPESTAT2
P0.29/AD0.2/CAP0.3/MAT0.3 14 35 P0.10/CAP1.0
P0.30/AD0.3/EINT3/CAP0.0 15 34 P0.9/RXD1/PWM6/EINT3
P1.16/TRACEPKT0 16 33 P0.8/TXD1/PWM4
P0.31 17
VSS 18
P0.0/TXD0/PWM1 19
P1.31/TRST 20
P0.1/RXD0/PWM3/EINT0 21
P0.2/SCL0/CAP0.0 22
VDD 23
P1.26/RTCK 24
VSS 25
P0.3/SDA0/MAT0.0/EINT1 26
P0.4/SCK0/CAP0.1/AD0.6 27
P1.25/EXTIN0 28
P0.5/MISO0/MAT0.1/AD0.7 29
P0.6/MOSI0/CAP0.2 30
P0.7/SSEL0/PWM2/EINT2 31
P1.24/TRACECLK 32

002aab406

Fig 14. LPC2132 and LPC2132/01 64-pin package

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54 P0.19/MAT1.2/MOSI1/CAP1.2
53 P0.18/CAP1.3/MISO1/MAT1.3
55 P0.20/MAT1.3/SSEL1/EINT3
64 P1.27/TDO

52 P1.30/TMS
56 P1.29/TCK
60 P1.28/TDI

57 RESET
62 XTAL1
61 XTAL2
63 VREF

58 P0.23

49 VBAT
59 VSSA

51 VDD
50 VSS
P0.21/PWM5/AD1.6/CAP1.3 1 48 P1.20/TRACESYNC
P0.22/AD1.7/CAP0.0/MAT0.0 2 47 P0.17/CAP1.2/SCK1/MAT1.2
RTCX1 3 46 P0.16/EINT0/MAT0.2/CAP0.2
P1.19/TRACEPKT3 4 45 P0.15/RI1/EINT2/AD1.5
RTCX2 5 44 P1.21/PIPESTAT0
VSS 6 43 VDD
VDDA 7 42 VSS
P1.18/TRACEPKT2 8 41 P0.14/DCD1/EINT1/SDA1
LPC2134, LPC2134/01
P0.25/AD0.4/AOUT 9 40 P1.22/PIPESTAT1
LPC2136, LPC2136/01
P0.26/AD0.5 10 LPC2138, LPC2138/01 39 P0.13/DTR1/MAT1.1/AD1.4
P0.27/AD0.0/CAP0.1/MAT0.1 11 38 P0.12/DSR1/MAT1.0/AD1.3
P1.17/TRACEPKT1 12 37 P0.11/CTS1/CAP1.1/SCL1
P0.28/AD0.1/CAP0.2/MAT0.2 13 36 P1.23/PIPESTAT2
P0.29/AD0.2/CAP0.3/MAT0.3 14 35 P0.10/RTS1/CAP1.0/AD1.2
P0.30/AD0.3/EINT3/CAP0.0 15 34 P0.9/RXD1/PWM6/EINT3
P1.16/TRACEPKT0 16 33 P0.8/TXD1/PWM4/AD1.1
P0.31 17
VSS 18
P0.0/TXD0/PWM1 19
P1.31/TRST 20
P0.1/RXD0/PWM3/EINT0 21
P0.2/SCL0/CAP0.0 22
VDD 23
P1.26/RTCK 24
VSS 25
P0.3/SDA0/MAT0.0/EINT1 26
P0.4/SCK0/CAP0.1/AD0.6 27
P1.25/EXTIN0 28
P0.5/MISO0/MAT0.1/AD0.7 29
P0.6/MOSI0/CAP0.2/AD1.0 30
P0.7/SSEL0/PWM2/EINT2 31
P1.24/TRACECLK 32

002aab407

Fig 15. LPC2134, LPC2136, LPC2138, LPC2134/01, LPC2136/01 and LPC2138/01 64-pin package

5.2 Pin description for LPC213x

Pin description for LPC213x and a brief explanation of corresponding functions are shown
in the following table.

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Table 35. Pin description

Symbol Pin Type Description
P0.0 to P0.31 I/O Port 0: Port 0 is a 32-bit I/O port with individual direction controls for each bit.
Total of 30 pins of the Port 0 can be used as a general purpose bi-directional
digital I/Os while P0.31 is output only pin. The operation of port 0 pins
depends upon the pin function selected via the pin connect block.
Pin P0.24 is not available.
P0.0/TXD0/ 19[1] I/O P0.0 — General purpose digital input/output pin.
PWM1 O TXD0 — Transmitter output for UART0.
O PWM1 — Pulse Width Modulator output 1.
P0.1/RxD0/ 21[2] I/O P0.1 — General purpose digital input/output pin.
PWM3/EINT0 I RxD0 — Receiver input for UART0.
O PWM3 — Pulse Width Modulator output 3.
I EINT0 — External interrupt 0 input.
P0.2/SCL0/ 22[3] I/O P0.2 — General purpose digital input/output pin.
CAP0.0 I/O SCL0 — I2C0 clock input/output. Open drain output (for I2C compliance).
I CAP0.0 — Capture input for Timer 0, channel 0.
P0.3/SDA0/ 26[3] I/O P0.3 — General purpose digital input/output pin.
MAT0.0/EINT1 I/O SDA0 — I2C0 data input/output. Open drain output (for I2C compliance).
O MAT0.0 — Match output for Timer 0, channel 0.
I EINT1 — External interrupt 1 input.
P0.4/SCK0/ 27[4] I/O P0.4 — General purpose digital input/output pin.
CAP0.1/AD0.6 I/O SCK0 — Serial clock for SPI0. SPI clock output from master or input to slave.
I CAP0.1 — Capture input for Timer 0, channel 1.
I AD0.6 — A/D converter 0, input 6.
P0.5/MISO0/ 29[4] I/O P0.5 — General purpose digital input/output pin.
MAT0.1/AD0.7 I/O MISO0 — Master In Slave Out for SPI0. Data input to SPI master or data
output from SPI slave.
O MAT0.1 — Match output for Timer 0, channel 1.
I AD0.7 — A/D converter 0, input 7.
P0.6/MOSI0/ 30[4] I/O P0.6 — General purpose digital input/output pin.
CAP0.2/AD1.0 I/O MOSI0 — Master Out Slave In for SPI0. Data output from SPI master or data
input to SPI slave.
I CAP0.2 — Capture input for Timer 0, channel 2
I AD1.0 — A/D converter 1, input 0 (LPC2134/6/8 and matching /01 only).
P0.7/SSEL0/ 31[2] I/O P0.7 — General purpose digital input/output pin.
PWM2/EINT2 I SSEL0 — Slave Select for SPI0. Selects the SPI interface as a slave.
O PWM2 — Pulse Width Modulator output 2.
I EINT2 — External interrupt 2 input.
P0.8/TXD1/ 33[4] I/O P0.8 — General purpose digital input/output pin.
PWM4/AD1.1 O TXD1 — Transmitter output for UART1.
O PWM4 — Pulse Width Modulator output 4.
I AD1.1 — A/D converter 1, input 1 (LPC2134/6/8 and matching /01 only).

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Table 35. Pin description …continued

Symbol Pin Type Description
P0.9/RxD1/ 34[2] I/O P0.9 — General purpose digital input/output pin.
PWM6/EINT3 I RxD1 — Receiver input for UART1.
O PWM6 — Pulse Width Modulator output 6.
I EINT3 — External interrupt 3 input.
P0.10/RTS1/ 35[4] I/O P0.10 — General purpose digital input/output pin.
CAP1.0/AD1.2 O RTS1 — Request to Send output for UART1; available in LPC2134/6/8 and
matching /01 devices only.
I CAP1.0 — Capture input for Timer 1, channel 0.
I AD1.2 — A/D converter 1, input 2 (LPC2134/6/8 and matching /01 only).
P0.11/CTS1/ 37[3] I/O P0.11 — General purpose digital input/output pin.
CAP1.1/SCL1 I CTS1 — Clear to Send input for UART1; available in LPC2134/6/8 and
matching /01 devices only
I CAP1.1 — Capture input for Timer 1, channel 1.
I/O SCL1 — I2C1 clock input/output. Open drain output (for I2C compliance)
P0.12/DSR1/ 38[4] I/O P0.12 — General purpose digital input/output pin
MAT1.0/AD1.3 I DSR1 — Data Set Ready input for UART1. Available in LPC2134/6/8 only.
O MAT1.0 — Match output for Timer 1, channel 0.
I AD1.3 — A/D converter input 3 (LPC2134/6/8 and matching /01 only).
P0.13/DTR1/ 39[4] I/O P0.13 — General purpose digital input/output pin
MAT1.1/AD1.4 O DTR1 — Data Terminal Ready output for UART1; available in LPC2134/6/8
and matching /01 devices only.
O MAT1.1 — Match output for Timer 1, channel 1.
I AD1.4 — A/D converter input 4 (LPC2134/6/8 and matching /01 only).
P0.14/DCD1/ 41[3] I/O P0.14 — General purpose digital input/output pin.
EINT1/SDA1 I DCD1 — Data Carrier Detect input for UART1; available in LPC2134/6/8 and
matching /01 devices only.
I EINT1 — External interrupt 1 input.
I/O SDA1 — I2C1 data input/output. Open drain output (for I2C compliance)
Note: LOW on this pin while RESET is LOW forces on-chip boot-loader to
take over control of the part after reset.
P0.15/RI1/ 45[4] I/O P0.15 — General purpose digital input/output pin.
EINT2/AD1.5 I RI1 — Ring Indicator input for UART1; available in LPC2134/6/8 and
matching /01 devices only.
I EINT2 — External interrupt 2 input.
I AD1.5 — A/D converter 1, input 5 (LPC2134/6/8 and matching /01 only).
P0.16/EINT0/ 46[2] I/O P0.16 — General purpose digital input/output pin.
MAT0.2/CAP0.2 I EINT0 — External interrupt 0 input.
O MAT0.2 — Match output for Timer 0, channel 2.
I CAP0.2 — Capture input for Timer 0, channel 2.

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Table 35. Pin description …continued

Symbol Pin Type Description
P0.17/CAP1.2/ 47[1] I/O P0.17 — General purpose digital input/output pin.
SCK1/MAT1.2 I CAP1.2 — Capture input for Timer 1, channel 2.
I/O SCK1 — Serial Clock for SSP. Clock output from master or input to slave.
O MAT1.2 — Match output for Timer 1, channel 2.
P0.18/CAP1.3/ 53[1] I/O P0.18 — General purpose digital input/output pin.
MISO1/MAT1.3 I CAP1.3 — Capture input for Timer 1, channel 3.
I/O MISO1 — Master In Slave Out for SSP. Data input to SPI master or data
output from SSP slave.
O MAT1.3 — Match output for Timer 1, channel 3.
P0.19/MAT1.2/ 54[1] I/O P0.19 — General purpose digital input/output pin.
MOSI1/CAP1.2 O MAT1.2 — Match output for Timer 1, channel 2.
I/O MOSI1 — Master Out Slave In for SSP. Data output from SSP master or data
input to SSP slave.
I CAP1.2 — Capture input for Timer 1, channel 2.
P0.20/MAT1.3/ 55[2] I/O P0.20 — General purpose digital input/output pin.
SSEL1/EINT3 O MAT1.3 — Match output for Timer 1, channel 3.
I SSEL1 — Slave Select for SSP. Selects the SSP interface as a slave.
I EINT3 — External interrupt 3 input.
P0.21/PWM5/ 1[4] I/O P0.21 — General purpose digital input/output pin.
AD1.6/CAP1.3 O PWM5 — Pulse Width Modulator output 5.
I AD1.6 — A/D converter 1, input 6 (LPC2134/6/8 and matching /01 only).
I CAP1.3 — Capture input for Timer 1, channel 3.
P0.22/AD1.7/ 2[4] I/O P0.22 — General purpose digital input/output pin.
CAP0.0/MAT0.0 I AD1.7 — A/D converter 1, input 7 (LPC2134/6/8 and matching /01 only).
I CAP0.0 — Capture input for Timer 0, channel 0.
O MAT0.0 — Match output for Timer 0, channel 0.
P0.23 58[1] I/O P0.23 — General purpose digital input/output pin.
P0.25/AD0.4/ 9[5] I/O P0.25 — General purpose digital input/output pin.
AOUT I AD0.4 — A/D converter 0, input 4.
O AOUT — D/A converter output; available in LPC2132/4/6/8 and matching /01
devices only.
P0.26/AD0.5 10[4] I/O P0.26 — General purpose digital input/output pin.
I AD0.5 — A/D converter 0, input 5.
P0.27/AD0.0/ 11[4] I/O P0.27 — General purpose digital input/output pin.
CAP0.1/MAT0.1 I AD0.0 — A/D converter 0, input 0.
I CAP0.1 — Capture input for Timer 0, channel 1.
O MAT0.1 — Match output for Timer 0, channel 1.
P0.28/AD0.1/ 13[4] I/O P0.28 — General purpose digital input/output pin.
CAP0.2/MAT0.2 I AD0.1 — A/D converter 0, input 1.
I CAP0.2 — Capture input for Timer 0, channel 2.
O MAT0.2 — Match output for Timer 0, channel 2.

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Table 35. Pin description …continued

Symbol Pin Type Description
P0.29/AD0.2/ 14[4] I/O P0.29 — General purpose digital input/output pin.
CAP0.3/MAT0.3 I AD0.2 — A/D converter 0, input 2.
I CAP0.3 — Capture input for Timer 0, Channel 3.
O MAT0.3 — Match output for Timer 0, channel 3.
P0.30/AD0.3/ 15[4] I/O P0.30 — General purpose digital input/output pin.
EINT3/CAP0.0 I AD0.3 — A/D converter 0, input 3.
I EINT3 — External interrupt 3 input.
I CAP0.0 — Capture input for Timer 0, channel 0.
P0.31 17[6] O P0.31 — General purpose digital output only pin
Note: This pin MUST NOT be externally pulled LOW when RESET pin is
LOW or the JTAG port will be disabled.
P1.0 to P1.31 I/O Port 1: Port 1 is a 32-bit bi-directional I/O port with individual direction
controls for each bit. The operation of port 1 pins depends upon the pin
function selected via the pin connect block. Pins 0 through 15 of port 1 are not
available.
P1.16/ 16[6] I/O P1.16 — General purpose digital input/output pin.
TRACEPKT0 O TRACEPKT0 — Trace Packet, bit 0. Standard I/O port with internal pull-up.
P1.17/ 12[6] I/O P1.17 — General purpose digital input/output pin.
TRACEPKT1 O TRACEPKT1 — Trace Packet, bit 1. Standard I/O port with internal pull-up.
P1.18/ 8[6] I/O P1.18 — General purpose digital input/output pin.
TRACEPKT2 O TRACEPKT2 — Trace Packet, bit 2. Standard I/O port with internal pull-up.
P1.19/ 4[6] I/O P1.19 — General purpose digital input/output pin.
TRACEPKT3 O TRACEPKT3 — Trace Packet, bit 3. Standard I/O port with internal pull-up.
P1.20/ 48[6] I/O P1.20 — General purpose digital input/output pin.
TRACESYNC O TRACESYNC — Trace Synchronization. Standard I/O port with internal
pull-up.
Note: LOW on this pin while RESET is LOW enables pins P1.25:16 to
operate as Trace port after reset
P1.21/ 44[6] I/O P1.21 — General purpose digital input/output pin.
PIPESTAT0 O PIPESTAT0 — Pipeline Status, bit 0. Standard I/O port with internal pull-up.
P1.22/ 40[6] I/O P1.22 — General purpose digital input/output pin.
PIPESTAT1 O PIPESTAT1 — Pipeline Status, bit 1. Standard I/O port with internal pull-up.
P1.23/ 36[6] I/O P1.23 — General purpose digital input/output pin.
PIPESTAT2 O PIPESTAT2 — Pipeline Status, bit 2. Standard I/O port with internal pull-up.
P1.24/ 32[6] I/O P1.24 — General purpose digital input/output pin.
TRACECLK O TRACECLK — Trace Clock. Standard I/O port with internal pull-up.
P1.25/EXTIN0 28[6] I/O P1.25 — General purpose digital input/output pin.
I EXTIN0 — External Trigger Input. Standard I/O with internal pull-up.

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Table 35. Pin description …continued

Symbol Pin Type Description
P1.26/RTCK 24[6] I/O P1.26 — General purpose digital input/output pin.
I/O RTCK — Returned Test Clock output. Extra signal added to the JTAG port.
Assists debugger synchronization when processor frequency varies.
Bi-directional pin with internal pull-up.
Note: LOW on this pin while RESET is LOW enables pins P1.31:26 to
operate as Debug port after reset
P1.27/TDO 64[6] I/O P1.27 — General purpose digital input/output pin.
O TDO — Test Data out for JTAG interface.
P1.28/TDI 60[6] I/O P1.28 — General purpose digital input/output pin.
I TDI — Test Data in for JTAG interface.
P1.29/TCK 56[6] I/O P1.29 — General purpose digital input/output pin.
I TCK — Test Clock for JTAG interface.
P1.30/TMS 52[6] I/O P1.30 — General purpose digital input/output pin.
I TMS — Test Mode Select for JTAG interface.
P1.31/TRST 20[6] I/O P1.31 — General purpose digital input/output pin.
I TRST — Test Reset for JTAG interface.
RESET 57[7] I External reset input: A LOW on this pin resets the device, causing I/O ports
and peripherals to take on their default states, and processor execution to
begin at address 0. TTL with hysteresis, 5 V tolerant.
XTAL1 62[8] I Input to the oscillator circuit and internal clock generator circuits.
XTAL2 61[8] O Output from the oscillator amplifier.
RTCX1 3[8] I Input to the RTC oscillator circuit. Can be left floating if the RTC is not used.
RTCX2 5[8] O Output from the RTC oscillator circuit. Can be left floating if the RTC is not
used.
VSS 6, 18, 25, 42, I Ground: 0 V reference.
50
VSSA 59 I Analog Ground: 0 V reference. This should nominally be the same voltage
as VSS, but should be isolated to minimize noise and error. This pin must be
grounded if the ADC/DAC are not used.
VDD 23, 43, 51 I 3.3 V Power Supply: This is the power supply voltage for the core and I/O
ports.
VDDA 7 I Analog 3.3 V Power Supply: This should be nominally the same voltage as
VDD but should be isolated to minimize noise and error. This voltage is used
to power the ADC(s) and DAC (where available). This pin must be tied to VDD
when the ADC/DAC are not used.
VREF 63 I A/D Converter Reference: This should be nominally the same voltage as
VDD but should be isolated to minimize noise and error. Level on this pin is
used as a reference for A/D converter and DAC (where available). This pin
must be tied to VDD when the ADC/DAC are not used.
VBAT 49 I RTC Power Supply: 3.3 V on this pin supplies the power to the RTC.

[1] Bidirectional pin; Plain input; 3 State Output; 10 ns Slew rate Control; TTL with Hysteresis; 5 V Tolerant.
[2] Bidirectional; 5 V tolerant; Input Glitch Filter (pulses shorter than 4 ns are ignored); 3 State Output; 10 ns Slew rate Control; TTL with
Hysteresis.
[3] I2C Pad; 400 kHz Specification; Open Drain; 5 V Tolerant.
[4] Bidirectional; Input Glitch Filter (pulses shorter than 4 ns are ignored); Analog I/O; digital receiver disable; 3 State Output; 10 ns Slew
Rate Control; TTL with Hysteresis; 5 V Tolerant

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[5] Bidirectional; 5 V tolerant; Analog I/O; digital receiver disable; 3 State Output; 10 ns Slew Rate Control; TTL with Hysteresis; DAC
enable output.
[6] Bidirectional pin; Plain input; 3 State Output; 10 ns Slew rate Control; TTL with Hysteresis; Pull-up; 5 V Tolerant.
[7] Input; TTL with Hysteresis; 5 V Tolerant (pulses shorter than 20 ns are ignored).
[8] Analog like pads having ESD structures only.

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6.1 Features
Allows individual pin configuration.

6.2 Applications
The purpose of the Pin Connect Block is to configure the microcontroller pins to the
desired functions.

6.3 Description
The pin connect block allows selected pins of the microcontroller to have more than one
function. Configuration registers control the multiplexers to allow connection between the
pin and the on chip peripherals.

Peripherals should be connected to the appropriate pins prior to being activated, and prior
to any related interrupt(s) being enabled. Activity of any enabled peripheral function that is
not mapped to a related pin should be considered undefined.

Selection of a single function on a port pin completely excludes all other functions
otherwise available on the same pin.

The only partial exception from the above rule of exclusion is the case of inputs to the A/D
converter. Regardless of the function that is selected for the port pin that also hosts the
A/D input, this A/D input can be read at any time and variations of the voltage level on this
pin will be reflected in the A/D readings. However, valid analog reading(s) can be obtained
if and only if the function of an analog input is selected. Only in this case proper interface
circuit is active in between the physical pin and the A/D module. In all other cases, a part
of digital logic necessary for the digital function to be performed will be active, and will
disrupt proper behavior of the A/D.

6.4 Register description

The Pin Control Module contains 2 registers as shown in Table 36 below.

Table 36. Pin connect block register map

Name Description Access Reset value[1] Address
PINSEL0 Pin function select Read/Write 0x0000 0000 0xE002 C000
register 0.
PINSEL1 Pin function select Read/Write 0x0000 0000 0xE002 C004
register 1.
PINSEL2 Pin function select Read/Write See Table 39 0xE002 C014
register 2.

[1] Reset value reflects the data stored in used bits only. It does not include reserved bits content.

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6.4.1 Pin Function Select Register 0 (PINSEL0 - 0xE002 C000)

The PINSEL0 register controls the functions of the pins as per the settings listed in
Table 40. The direction control bit in the IO0DIR register is effective only when the GPIO
function is selected for a pin. For other functions, direction is controlled automatically.

Table 37. Pin function Select register 0 (PINSEL0 - address 0xE002 C000) bit description
Bit Symbol Value Function Reset value
1:0 P0.0 00 GPIO Port 0.0 0
01 TXD (UART0)
10 PWM1
11 Reserved
3:2 P0.1 00 GPIO Port 0.1 0
01 RxD (UART0)
10 PWM3
11 EINT0
5:4 P0.2 00 GPIO Port 0.2 0
01 SCL0 (I2C0)
10 Capture 0.0 (Timer 0)
11 Reserved
7:6 P0.3 00 GPIO Port 0.3 0
01 SDA0 (I2C0)
10 Match 0.0 (Timer 0)
11 EINT1
9:8 P0.4 00 GPIO Port 0.4 0
01 SCK0 (SPI0)
10 Capture 0.1 (Timer 0)
11 AD0.6
11:10 P0.5 00 GPIO Port 0.5 0
01 MISO0 (SPI0)
10 Match 0.1 (Timer 0)
11 AD0.7
13:12 P0.6 00 GPIO Port 0.6 0
01 MOSI0 (SPI0)
10 Capture 0.2 (Timer 0)
11 Reserved[1][2] or AD1.0[3]
15:14 P0.7 00 GPIO Port 0.7 0
01 SSEL0 (SPI0)
10 PWM2
11 EINT2
17:16 P0.8 00 GPIO Port 0.8 0
01 TXD UART1
10 PWM4
11 Reserved[1][2] or AD1.1[3]

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Table 37. Pin function Select register 0 (PINSEL0 - address 0xE002 C000) bit description
Bit Symbol Value Function Reset value
19:18 P0.9 00 GPIO Port 0.9 0
01 RxD (UART1)
10 PWM6
11 EINT3
21:20 P0.10 00 GPIO Port 0.10 0
01 Reserved[1][2] or RTS (UART1)[3]
10 Capture 1.0 (Timer 1)
11 Reserved[1][2] or AD1.2[3]
23:22 P0.11 00 GPIO Port 0.11 0
01 Reserved[1][2] or CTS (UART1)[3]
10 Capture 1.1 (Timer 1)
11 SCL1 (I2C1)
25:24 P0.12 00 GPIO Port 0.12 0
01 Reserved[1][2] or DSR (UART1)[3]
10 Match 1.0 (Timer 1)
11 Reserved[1][2] or AD1.3[3]
27:26 P0.13 00 GPIO Port 0.13 0
01 Reserved[1][2] or DTR (UART1)[3]
10 Match 1.1 (Timer 1)
11 Reserved[1][2] or AD1.4[3]
29:28 P0.14 00 GPIO Port 0.14 0
01 Reserved[1][2] or DCD (UART1)[3]
10 EINT1
11 SDA1 (I2C1)
31:30 P0.15 00 GPIO Port 0.15 0
01 Reserved[1][2] or RI (UART1)[3]
10 EINT2
11 Reserved[1][2] or AD1.5[3]

[1] Available on LPC2131 and LPC2131/01.

[2] Available on LPC2132 and LPC2132/01.
[3] Available on LPC2134/6/8, LPC2134/01, LPC2136/01, and LPC2138/01.

6.4.2 Pin function Select register 1 (PINSEL1 - 0xE002 C004)

The PINSEL1 register controls the functions of the pins as per the settings listed in
following tables. The direction control bit in the IO0DIR register is effective only when the
GPIO function is selected for a pin. For other functions direction is controlled
automatically.

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Table 38. Pin function Select register 1 (PINSEL1 - address 0xE002 C004) bit description
Bit Symbol Value Function Reset value
1:0 P0.16 00 GPIO Port 0.16 0
01 EINT0
10 Match 0.2 (Timer 0)
11 Capture 0.2 (Timer 0)
3:2 P0.17 00 GPIO Port 0.17 0
01 Capture 1.2 (Timer 1)
10 SCK (SSP)
11 Match 1.2 (Timer 1)
5:4 P0.18 00 GPIO Port 0.18 0
01 Capture 1.3 (Timer 1)
10 MISO (SSP)
11 Match 1.3 (Timer 1)
7:6 P0.19 00 GPIO Port 0.19 0
01 Match 1.2 (Timer 1)
10 MOSI (SSP)
11 Capture 1.2 (Timer 1)
9:8 P0.20 00 GPIO Port 0.20 0
01 Match 1.3 (Timer 1)
10 SSEL (SSP)
11 EINT3
11:10 P0.21 00 GPIO Port 0.21 0
01 PWM5
10 Reserved[1][2] or AD1.6[3]
11 Capture 1.3 (Timer 1)
13:12 P0.22 00 GPIO Port 0.22 0
01 Reserved[1][2] or AD1.7[3]
10 Capture 0.0 (Timer 0)
11 Match 0.0 (Timer 0)
15:14 P0.23 00 GPIO Port 0.23 0
01 Reserved
10 Reserved
11 Reserved
17:16 P0.24 00 Reserved 0
01 Reserved
10 Reserved
11 Reserved
19:18 P0.25 00 GPIO Port 0.25 0
01 AD0.4
10 Reserved[1] or AOUT(DAC)[2][3]
11 Reserved

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Table 38. Pin function Select register 1 (PINSEL1 - address 0xE002 C004) bit description
Bit Symbol Value Function Reset value
21:20 P0.26 00 GPIO Port 0.26 0
01 AD0.5
10 Reserved
11 Reserved
23:22 P0.27 00 GPIO Port 0.27 0
01 AD0.0
10 Capture 0.1 (Timer 0)
11 Match 0.1 (Timer 0)
25:24 P0.28 00 GPIO Port 0.28 0
01 AD0.1
10 Capture 0.2 (Timer 0)
11 Match 0.2 (Timer 0)
27:26 P0.29 00 GPIO Port 0.29 0
01 AD0.2
10 Capture 0.3 (Timer 0)
11 Match 0.3 (Timer 0)
29:28 P0.30 00 GPIO Port 0.30 0
01 AD0.3
10 EINT3
11 Capture 0.0 (Timer 0)
31:30 P0.31 00 GPO Port only 0
01 Reserved
10 Reserved
11 Reserved

[1] Available on LPC2131 and LPC2131/01.

[2] Available on LPC2132 and LPC2132/01.
[3] Available on LPC2134/6/8, LPC2134/01, LPC2136/01, and LPC2138/01.

6.4.3 Pin function Select register 2 (PINSEL2 - 0xE002 C014)

The PINSEL2 register controls the functions of the pins as per the settings listed in
Table 39. The direction control bit in the IO1DIR register is effective only when the GPIO
function is selected for a pin. For other functions direction is controlled automatically.

Warning: use read-modify-write operation when accessing PINSEL2 register. Accidental

write of 0 to bit 2 and/or bit 3 results in loss of debug and/or trace functionality! Changing
of either bit 2 or bit 3 from 1 to 0 may cause an incorrect code execution!

The Debug modes are entered as follows:

• During reset, if P1.26 is pulled low (weak bias resistor is connected from P1.26 to
Vss), JTAG pins will be available.
• During reset, if P1.20 is pulled low (weak bias resistor is connected from P1.20 to
Vss), Trace port will be available.

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Reset value for bit 2 of PINSEL2 register will be inverse of the external state of the
P1.26/RTCK. Reset value for bit 2 will be set to 1 if P1.26/RTCK is externally pulled low
and reset value for bit 2 will be set to 0 if there is no pull-down.

Reset value for bit 3 of PINSEL2 register will be inverse of the external state of the
P1.20/TRACESYNC. Reset value for bit 3 will be set to 1 if P1.20/TRACESYNC IS
externally pulled low and reset value for bit 3 will be set to 0 if there is no pull-down.

Pins P1.31 thru 16 can be determined via hardware pins prior to de-asserting of reset.

Table 39. Pin function Select register 2 (PINSEL2 - 0xE002 C014) bit description
Bit Symbol Value Function Reset value
1:0 - - Reserved, user software should not write ones NA
to reserved bits. The value read from a reserved
bit is not defined.
2 GPIO/DEBUG 0 Pins P1.36-26 are used as GPIO pins. P1.26/RTCK
1 Pins P1.36-26 are used as a Debug port.
3 GPIO/TRACE 0 Pins P1.25-16 are used as GPIO pins. P1.20/
TRACESYNC
1 Pins P1.25-16 are used as a Trace port.
31:4 - - Reserved, user software should not write ones NA
to reserved bits. The value read from a reserved
bit is not defined.

6.4.4 Pin function select register values

The PINSEL registers control the functions of device pins as shown below. Pairs of bits in
these registers correspond to specific device pins.

Table 40. Pin function select register bits

PINSEL0 and PINSEL1 Values Function Value after Reset
00 Primary (default) function, typically GPIO 00
port
01 First alternate function
10 Second alternate function
11 Reserved

The direction control bit in the IO0DIR/IO1DIR register is effective only when the GPIO
function is selected for a pin. For other functions, direction is controlled automatically.
Each derivative typically has a different pinout and therefore a different set of functions
possible for each pin. Details for a specific derivative may be found in the appropriate data
sheet.

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7.1 Features
• ARM PrimeCell Vectored Interrupt Controller
• 32 interrupt request inputs
• 16 vectored IRQ interrupts
• 16 priority levels dynamically assigned to interrupt requests
• Software interrupt generation

7.2 Description
The Vectored Interrupt Controller (VIC) takes 32 interrupt request inputs and
programmably assigns them into 3 categories, FIQ, vectored IRQ, and non-vectored IRQ.
The programmable assignment scheme means that priorities of interrupts from the
various peripherals can be dynamically assigned and adjusted.

Fast Interrupt reQuest (FIQ) requests have the highest priority. If more than one request is
assigned to FIQ, the VIC ORs the requests to produce the FIQ signal to the ARM
processor. The fastest possible FIQ latency is achieved when only one request is
classified as FIQ, because then the FIQ service routine can simply start dealing with that
device. But if more than one request is assigned to the FIQ class, the FIQ service routine
can read a word from the VIC that identifies which FIQ source(s) is (are) requesting an
interrupt.

Vectored IRQs have the middle priority, but only 16 of the 32 requests can be assigned to
this category. Any of the 32 requests can be assigned to any of the 16 vectored IRQ slots,
among which slot 0 has the highest priority and slot 15 has the lowest.

Non-vectored IRQs have the lowest priority.

The VIC ORs the requests from all the vectored and non-vectored IRQs to produce the
IRQ signal to the ARM processor. The IRQ service routine can start by reading a register
from the VIC and jumping there. If any of the vectored IRQs are requesting, the VIC
provides the address of the highest-priority requesting IRQs service routine, otherwise it
provides the address of a default routine that is shared by all the non-vectored IRQs. The
default routine can read another VIC register to see what IRQs are active.

All registers in the VIC are word registers. Byte and halfword reads and write are not
supported.

Additional information on the Vectored Interrupt Controller is available in the ARM

PrimeCell Vectored Interrupt Controller (PL190) documentation.

7.3 Register description

The VIC implements the registers shown in Table 41. More detailed descriptions follow.

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Table 41. VIC register map

Name Description Access Reset Address
value[1]
VICIRQStatus IRQ Status Register. This register reads out the state of RO 0 0xFFFF F000
those interrupt requests that are enabled and classified as
IRQ.
VICFIQStatus FIQ Status Requests. This register reads out the state of RO 0 0xFFFF F004
those interrupt requests that are enabled and classified as
FIQ.
VICRawIntr Raw Interrupt Status Register. This register reads out the RO 0 0xFFFF F008
state of the 32 interrupt requests / software interrupts,
regardless of enabling or classification.
VICIntSelect Interrupt Select Register. This register classifies each of the R/W 0 0xFFFF F00C
32 interrupt requests as contributing to FIQ or IRQ.
VICIntEnable Interrupt Enable Register. This register controls which of the R/W 0 0xFFFF F010
32 interrupt requests and software interrupts are enabled to
contribute to FIQ or IRQ.
VICIntEnClr Interrupt Enable Clear Register. This register allows WO 0 0xFFFF F014
software to clear one or more bits in the Interrupt Enable
register.
VICSoftInt Software Interrupt Register. The contents of this register are R/W 0 0xFFFF F018
ORed with the 32 interrupt requests from various peripheral
functions.
VICSoftIntClear Software Interrupt Clear Register. This register allows WO 0 0xFFFF F01C
software to clear one or more bits in the Software Interrupt
register.
VICProtection Protection enable register. This register allows limiting R/W 0 0xFFFF F020
access to the VIC registers by software running in privileged
mode.
VICVectAddr Vector Address Register. When an IRQ interrupt occurs, the R/W 0 0xFFFF F030
IRQ service routine can read this register and jump to the
value read.
VICDefVectAddr Default Vector Address Register. This register holds the R/W 0 0xFFFF F034
address of the Interrupt Service routine (ISR) for
non-vectored IRQs.
VICVectAddr0 Vector address 0 register. Vector Address Registers 0-15 R/W 0 0xFFFF F100
hold the addresses of the Interrupt Service routines (ISRs)
for the 16 vectored IRQ slots.
VICVectAddr1 Vector address 1 register. R/W 0 0xFFFF F104
VICVectAddr2 Vector address 2 register. R/W 0 0xFFFF F108
VICVectAddr3 Vector address 3 register. R/W 0 0xFFFF F10C
VICVectAddr4 Vector address 4 register. R/W 0 0xFFFF F110
VICVectAddr5 Vector address 5 register. R/W 0 0xFFFF F114
VICVectAddr6 Vector address 6 register. R/W 0 0xFFFF F118
VICVectAddr7 Vector address 7 register. R/W 0 0xFFFF F11C
VICVectAddr8 Vector address 8 register. R/W 0 0xFFFF F120
VICVectAddr9 Vector address 9 register. R/W 0 0xFFFF F124
VICVectAddr10 Vector address 10 register. R/W 0 0xFFFF F128
VICVectAddr11 Vector address 11 register. R/W 0 0xFFFF F12C

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Table 41. VIC register map

Name Description Access Reset Address
value[1]
VICVectAddr12 Vector address 12 register. R/W 0 0xFFFF F130
VICVectAddr13 Vector address 13 register. R/W 0 0xFFFF F134
VICVectAddr14 Vector address 14 register. R/W 0 0xFFFF F138
VICVectAddr15 Vector address 15 register. R/W 0 0xFFFF F13C
VICVectCntl0 Vector control 0 register. Vector Control Registers 0-15 each R/W 0 0xFFFF F200
control one of the 16 vectored IRQ slots. Slot 0 has the
highest priority and slot 15 the lowest.
VICVectCntl1 Vector control 1 register. R/W 0 0xFFFF F204
VICVectCntl2 Vector control 2 register. R/W 0 0xFFFF F208
VICVectCntl3 Vector control 3 register. R/W 0 0xFFFF F20C
VICVectCntl4 Vector control 4 register. R/W 0 0xFFFF F210
VICVectCntl5 Vector control 5 register. R/W 0 0xFFFF F214
VICVectCntl6 Vector control 6 register. R/W 0 0xFFFF F218
VICVectCntl7 Vector control 7 register. R/W 0 0xFFFF F21C
VICVectCntl8 Vector control 8 register. R/W 0 0xFFFF F220
VICVectCntl9 Vector control 9 register. R/W 0 0xFFFF F224
VICVectCntl10 Vector control 10 register. R/W 0 0xFFFF F228
VICVectCntl11 Vector control 11 register. R/W 0 0xFFFF F22C
VICVectCntl12 Vector control 12 register. R/W 0 0xFFFF F230
VICVectCntl13 Vector control 13 register. R/W 0 0xFFFF F234
VICVectCntl14 Vector control 14 register. R/W 0 0xFFFF F238
VICVectCntl15 Vector control 15 register. R/W 0 0xFFFF F23C

[1] Reset value reflects the data stored in used bits only. It does not include reserved bits content.

7.4 VIC registers

The following section describes the VIC registers in the order in which they are used in the
VIC logic, from those closest to the interrupt request inputs to those most abstracted for
use by software. For most people, this is also the best order to read about the registers
when learning the VIC.

7.4.1 Software Interrupt register (VICSoftInt - 0xFFFF F018)

The contents of this register are ORed with the 32 interrupt requests from the various
peripherals, before any other logic is applied.

Table 42. Software Interrupt register (VICSoftInt - address 0xFFFF F018) bit allocation
Reset value: 0x0000 0000
Bit 31 30 29 28 27 26 25 24
Symbol - - - - - - - -
Access R/W R/W R/W R/W R/W R/W R/W R/W

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Bit 23 22 21 20 19 18 17 16
Symbol - - AD1 BOD I2C1 AD0 EINT3 EINT2
Access R/W R/W R/W R/W R/W R/W R/W R/W
Bit 15 14 13 12 11 10 9 8
Symbol EINT1 EINT0 RTC PLL SPI1/SSP SPI0 I2C0 PWM0
Access R/W R/W R/W R/W R/W R/W R/W R/W
Bit 7 6 5 4 3 2 1 0
Symbol UART1 UART0 TIMER1 TIMER0 ARMCore1 ARMCore0 - WDT
Access R/W R/W R/W R/W R/W R/W R/W R/W

Table 43. Software Interrupt register (VICSoftInt - address 0xFFFF F018) bit description
Bit Symbol Value Description Reset
value
31:0 See VICSoftInt 0 Do not force the interrupt request with this bit number. Writing 0
bit allocation zeroes to bits in VICSoftInt has no effect, see VICSoftIntClear
table. (Section 7.4.2).
1 Force the interrupt request with this bit number.

7.4.2 Software Interrupt Clear register (VICSoftIntClear - 0xFFFF F01C)

This register allows software to clear one or more bits in the Software Interrupt register,
without having to first read it.

Table 44. Software Interrupt Clear register (VICSoftIntClear - address 0xFFFF F01C) bit allocation
Reset value: 0x0000 0000
Bit 31 30 29 28 27 26 25 24
Symbol - - - - - - - -
Access WO WO WO WO WO WO WO WO
Bit 23 22 21 20 19 18 17 16
Symbol - - AD1 BOD I2C1 AD0 EINT3 EINT2
Access WO WO WO WO WO WO WO WO
Bit 15 14 13 12 11 10 9 8
Symbol EINT1 EINT0 RTC PLL SPI1/SSP SPI0 I2C0 PWM0
Access WO WO WO WO WO WO WO WO
Bit 7 6 5 4 3 2 1 0
Symbol UART1 UART0 TIMER1 TIMER0 ARMCore1 ARMCore0 - WDT
Access WO WO WO WO WO WO WO WO

Table 45. Software Interrupt Clear register (VICSoftIntClear - address 0xFFFF F01C) bit description
Bit Symbol Value Description Reset
value
31:0 See 0 Writing a 0 leaves the corresponding bit in VICSoftInt unchanged. 0
VICSoftIntClea 1 Writing a 1 clears the corresponding bit in the Software Interrupt
r bit allocation register, thus releasing the forcing of this request.
table.

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7.4.3 Raw Interrupt status register (VICRawIntr - 0xFFFF F008)

This is a read only register. This register reads out the state of the 32 interrupt requests
and software interrupts, regardless of enabling or classification.

Table 46. Raw Interrupt status register (VICRawIntr - address 0xFFFF F008) bit allocation
Reset value: 0x0000 0000
Bit 31 30 29 28 27 26 25 24
Symbol - - - - - - - -
Access RO RO RO RO RO RO RO RO
Bit 23 22 21 20 19 18 17 16
Symbol - - AD1 BOD I2C1 AD0 EINT3 EINT2
Access RO RO RO RO RO RO RO RO
Bit 15 14 13 12 11 10 9 8
Symbol EINT1 EINT0 RTC PLL SPI1/SSP SPI0 I2C0 PWM0
Access RO RO RO RO RO RO RO RO
Bit 7 6 5 4 3 2 1 0
Symbol UART1 UART0 TIMER1 TIMER0 ARMCore1 ARMCore0 - WDT
Access RO RO RO RO RO RO RO RO

Table 47. Raw Interrupt status register (VICRawIntr - address 0xFFFF F008) bit description
Bit Symbol Value Description Reset
value
31:0 See 0 The interrupt request or software interrupt with this bit number is 0
VICRawIntr bit negated.
allocation 1 The interrupt request or software interrupt with this bit number is
table. negated.

7.4.4 Interrupt Enable register (VICIntEnable - 0xFFFF F010)

This is a read/write accessible register. This register controls which of the 32 interrupt
requests and software interrupts contribute to FIQ or IRQ.

Table 48. Interrupt Enable register (VICIntEnable - address 0xFFFF F010) bit allocation
Reset value: 0x0000 0000
Bit 31 30 29 28 27 26 25 24
Symbol - - - - - - - -
Access R/W R/W R/W R/W R/W R/W R/W R/W
Bit 23 22 21 20 19 18 17 16
Symbol - - AD1 BOD I2C1 AD0 EINT3 EINT2
Access R/W R/W R/W R/W R/W R/W R/W R/W
Bit 15 14 13 12 11 10 9 8
Symbol EINT1 EINT0 RTC PLL SPI1/SSP SPI0 I2C0 PWM0
Access R/W R/W R/W R/W R/W R/W R/W R/W
Bit 7 6 5 4 3 2 1 0
Symbol UART1 UART0 TIMER1 TIMER0 ARMCore1 ARMCore0 - WDT
Access R/W R/W R/W R/W R/W R/W R/W R/W

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Table 49. Interrupt Enable register (VICIntEnable - address 0xFFFF F010) bit description
Bit Symbol Description Reset
value
31:0 See When this register is read, 1s indicate interrupt requests or software interrupts 0
VICIntEnable that are enabled to contribute to FIQ or IRQ.
bit allocation When this register is written, ones enable interrupt requests or software
table. interrupts to contribute to FIQ or IRQ, zeroes have no effect. See Section 7.4.5
“Interrupt Enable Clear register (VICIntEnClear - 0xFFFF F014)” on page 69
and Table 51 below for how to disable interrupts.

7.4.5 Interrupt Enable Clear register (VICIntEnClear - 0xFFFF F014)

This is a write only register. This register allows software to clear one or more bits in the
Interrupt Enable register (see Section 7.4.4 “Interrupt Enable register (VICIntEnable -
0xFFFF F010)” on page 68), without having to first read it.

Table 50. Software Interrupt Clear register (VICIntEnClear - address 0xFFFF F014) bit allocation
Reset value: 0x0000 0000
Bit 31 30 29 28 27 26 25 24
Symbol - - - - - - - -
Access WO WO WO WO WO WO WO WO
Bit 23 22 21 20 19 18 17 16
Symbol - - AD1 BOD I2C1 AD0 EINT3 EINT2
Access WO WO WO WO WO WO WO WO
Bit 15 14 13 12 11 10 9 8
Symbol EINT1 EINT0 RTC PLL SPI1/SSP SPI0 I2C0 PWM0
Access WO WO WO WO WO WO WO WO
Bit 7 6 5 4 3 2 1 0
Symbol UART1 UART0 TIMER1 TIMER0 ARMCore1 ARMCore0 - WDT
Access WO WO WO WO WO WO WO WO

Table 51. Software Interrupt Clear register (VICIntEnClear - address 0xFFFF F014) bit description
Bit Symbol Value Description Reset
value
31:0 See 0 Writing a 0 leaves the corresponding bit in VICIntEnable 0
VICIntEnClear unchanged.
bit allocation 1 Writing a 1 clears the corresponding bit in the Interrupt Enable
table. register, thus disabling interrupts for this request.

7.4.6 Interrupt Select register (VICIntSelect - 0xFFFF F00C)

This is a read/write accessible register. This register classifies each of the 32 interrupt
requests as contributing to FIQ or IRQ.

Table 52. Interrupt Select register (VICIntSelect - address 0xFFFF F00C) bit allocation
Reset value: 0x0000 0000
Bit 31 30 29 28 27 26 25 24
Symbol - - - - - - - -
Access R/W R/W R/W R/W R/W R/W R/W R/W

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Table 53. Interrupt Select register (VICIntSelect - address 0xFFFF F00C) bit description
Bit Symbol Value Description Reset
value
31:0 See 0 The interrupt request with this bit number is assigned to the IRQ 0
VICIntSelect category.
bit allocation 1 The interrupt request with this bit number is assigned to the FIQ
table. category.

7.4.7 IRQ Status register (VICIRQStatus - 0xFFFF F000)

This is a read only register. This register reads out the state of those interrupt requests
that are enabled and classified as IRQ. It does not differentiate between vectored and
non-vectored IRQs.

Table 54. IRQ Status register (VICIRQStatus - address 0xFFFF F000) bit allocation
Reset value: 0x0000 0000
Bit 31 30 29 28 27 26 25 24
Symbol - - - - - - - -
Access RO RO RO RO RO RO RO RO
Bit 23 22 21 20 19 18 17 16
Symbol - - AD1 BOD I2C1 AD0 EINT3 EINT2
Access RO RO RO RO RO RO RO RO
Bit 15 14 13 12 11 10 9 8
Symbol EINT1 EINT0 RTC PLL SPI1/SSP SPI0 I2C0 PWM0
Access RO RO RO RO RO RO RO RO
Bit 7 6 5 4 3 2 1 0
Symbol UART1 UART0 TIMER1 TIMER0 ARMCore1 ARMCore0 - WDT
Access RO RO RO RO RO RO RO RO

Table 55. IRQ Status register (VICIRQStatus - address 0xFFFF F000) bit description
Bit Symbol Description Reset
value
31:0 See A bit read as 1 indicates a corresponding interrupt request being enabled, 0
VICIRQStatus classified as IRQ, and asserted
bit allocation
table.

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7.4.8 FIQ Status register (VICFIQStatus - 0xFFFF F004)

This is a read only register. This register reads out the state of those interrupt requests
that are enabled and classified as FIQ. If more than one request is classified as FIQ, the
FIQ service routine can read this register to see which request(s) is (are) active.

Table 56. FIQ Status register (VICFIQStatus - address 0xFFFF F004) bit allocation
Reset value: 0x0000 0000
Bit 31 30 29 28 27 26 25 24
Symbol - - - - - - - -
Access RO RO RO RO RO RO RO RO
Bit 23 22 21 20 19 18 17 16
Symbol - - AD1 BOD I2C1 AD0 EINT3 EINT2
Access RO RO RO RO RO RO RO RO
Bit 15 14 13 12 11 10 9 8
Symbol EINT1 EINT0 RTC PLL SPI1/SSP SPI0 I2C0 PWM0
Access RO RO RO RO RO RO RO RO
Bit 7 6 5 4 3 2 1 0
Symbol UART1 UART0 TIMER1 TIMER0 ARMCore1 ARMCore0 - WDT
Access RO RO RO RO RO RO RO RO

Table 57. FIQ Status register (VICFIQStatus - address 0xFFFF F004) bit description
Bit Symbol Description Reset
value
31:0 See A bit read as 1 indicates a corresponding interrupt request being enabled, 0
VICFIQStatus classified as IRQ, and asserted
bit allocation
table.

7.4.9 Vector Control registers 0-15 (VICvectCntl0-15 - 0xFFFF F200-23C)

These are a read/write accessible registers. Each of these registers controls one of the 16
vectored IRQ slots. Slot 0 has the highest priority and slot 15 the lowest. Note that
disabling a vectored IRQ slot in one of the VICVectCntl registers does not disable the
interrupt itself, the interrupt is simply changed to the non-vectored form.

Table 58. Vector Control registers 0-15 (VICvectCntl0-15 - 0xFFFF F200-23C) bit description
Bit Symbol Description Reset
value
4:0 int_request/ The number of the interrupt request or software interrupt assigned to this 0
sw_int_assig vectored IRQ slot. As a matter of good programming practice, software should
not assign the same interrupt number to more than one enabled vectored IRQ
slot. But if this does occur, the lower numbered slot will be used when the
interrupt request or software interrupt is enabled, classified as IRQ, and
asserted.
5 IRQslot_en When 1, this vectored IRQ slot is enabled, and can produce a unique ISR 0
address when its assigned interrupt request or software interrupt is enabled,
classified as IRQ, and asserted.
31:6 - Reserved, user software should not write ones to reserved bits. The value read NA
from a reserved bit is not defined.

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For example, the following two lines assign slot 0 to SPI0 IRQ interrupt request(s) and slot
1 to TIMER0 IRQ interrupt request(s):

VICVectCntl0 = 0x20 | 10;

VICVectCntl1 = 0x20 | 4;

See Table 63 “Connection of interrupt sources to the Vectored Interrupt Controller (VIC)”
on page 73 for details on interrupt source channels.

7.4.10 Vector Address registers 0-15 (VICVectAddr0-15 - 0xFFFF F100-13C)

These are a read/write accessible registers. These registers hold the addresses of the
Interrupt Service routines (ISRs) for the 16 vectored IRQ slots.

Table 59. Vector Address registers (VICVectAddr0-15 - addresses 0xFFFF F100-13C) bit description
Bit Symbol Description Reset value
31:0 IRQ_vector When one or more interrupt request or software interrupt is (are) enabled, 0x0000 0000
classified as IRQ, asserted, and assigned to an enabled vectored IRQ slot,
the value from this register for the highest-priority such slot will be provided
when the IRQ service routine reads the Vector Address register -VICVectAddr
(Section 7.4.10).

7.4.11 Default Vector Address register (VICDefVectAddr - 0xFFFF F034)

This is a read/write accessible register. This register holds the address of the Interrupt
Service routine (ISR) for non-vectored IRQs.

Table 60. Default Vector Address register (VICDefVectAddr - address 0xFFFF F034) bit description
Bit Symbol Description Reset value
31:0 IRQ_vector When an IRQ service routine reads the Vector Address register 0x0000 0000
(VICVectAddr), and no IRQ slot responds as described above, this address is
returned.

7.4.12 Vector Address register (VICVectAddr - 0xFFFF F030)

This is a read/write accessible register. When an IRQ interrupt occurs, the IRQ service
routine can read this register and jump to the value read.

Table 61. Vector Address register (VICVectAddr - address 0xFFFF F030) bit description
Bit Symbol Description Reset value
31:0 IRQ_vector If any of the interrupt requests or software interrupts that are assigned to a 0x0000 0000
vectored IRQ slot is (are) enabled, classified as IRQ, and asserted, reading
from this register returns the address in the Vector Address Register for the
highest-priority such slot (lowest-numbered) such slot. Otherwise it returns the
address in the Default Vector Address Register.
Writing to this register does not set the value for future reads from it. Rather,
this register should be written near the end of an ISR, to update the priority
hardware.

7.4.13 Protection Enable register (VICProtection - 0xFFFF F020)

This is a read/write accessible register. This one-bit register controls access to the VIC
registers by software running in User mode.

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Table 62. Protection Enable register (VICProtection - address 0xFFFF F020) bit description
Bit Symbol Value Description Reset
value
0 VIC_access 0 VIC registers can be accessed in User or privileged mode. 0
1 The VIC registers can only be accessed in privileged mode.
31:1 - Reserved, user software should not write ones to reserved bits. The NA
value read from a reserved bit is not defined.

7.5 Interrupt sources

Table 63 lists the interrupt sources for each peripheral function. Each peripheral device
has one interrupt line connected to the Vectored Interrupt Controller, but may have several
internal interrupt flags. Individual interrupt flags may also represent more than one
interrupt source.

Table 63. Connection of interrupt sources to the Vectored Interrupt Controller (VIC)
Block Flag(s) VIC Channel # and Hex
Mask
WDT Watchdog Interrupt (WDINT) 0 0x0000 0001
- Reserved for Software Interrupts only 1 0x0000 0002
ARM Core Embedded ICE, DbgCommRx 2 0x0000 0004
ARM Core Embedded ICE, DbgCommTX 3 0x0000 0008
TIMER0 Match 0 - 3 (MR0, MR1, MR2, MR3) 4 0x0000 0010
Capture 0 - 3 (CR0, CR1, CR2, CR3)
TIMER1 Match 0 - 3 (MR0, MR1, MR2, MR3) 5 0x0000 0020
Capture 0 - 3 (CR0, CR1, CR2, CR3)
UART0 Rx Line Status (RLS) 6 0x0000 0040
Transmit Holding Register Empty (THRE)
Rx Data Available (RDA)
Character Time-out Indicator (CTI)
UART1 Rx Line Status (RLS) 7 0x0000 0080
Transmit Holding Register Empty (THRE)
Rx Data Available (RDA)
Character Time-out Indicator (CTI)
Modem Status Interrupt (MSI)[1]
PWM0 Match 0 - 6 (MR0, MR1, MR2, MR3, MR4, MR5, MR6) 8 0x0000 0100
I2C0 SI (state change) 9 0x0000 0200
SPI0 SPI Interrupt Flag (SPIF) 10 0x0000 0400
Mode Fault (MODF)
SPI1 (SSP) TX FIFO at least half empty (TXRIS) 11 0x0000 0800
Rx FIFO at least half full (RXRIS)
Receive Timeout condition (RTRIS)
Receive overrun (RORRIS)
PLL PLL Lock (PLOCK) 12 0x0000 1000
RTC Counter Increment (RTCCIF) 13 0x0000 2000
Alarm (RTCALF)

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Table 63. Connection of interrupt sources to the Vectored Interrupt Controller (VIC)
Block Flag(s) VIC Channel # and Hex
Mask
System Control External Interrupt 0 (EINT0) 14 0x0000 4000
External Interrupt 1 (EINT1) 15 0x0000 8000
External Interrupt 2 (EINT2) 16 0x0001 0000
External Interrupt 3 (EINT3) 17 0x0002 0000
ADC0 A/D Converter 0 end of conversion 18 0x0004 0000
I2C1 SI (state change) 19 0x0008 0000
BOD Brown Out detect 20 0x0010 0000
ADC1 A/D Converter 1 end of conversion[1] 21 0x0020 0000

[1] Not available in LPC2131, LPC2131/01, LPC2132, and LPC2132/01.

interrupt request, masking and selection

nVICFIQIN non-vectored FIQ interrupt logic
SOFTINTCLEAR INTENABLECLEAR
[31:0] [31:0]

SOFTINT INTENABLE FIQSTATUS[31:0] FIQSTATUS

[31:0] [31:0] [31:0] nVICFIQ

VICINT
SOURCE
non-vectored IRQ interrupt logic
[31:0] IRQSTATUS[31:0]
IRQ NonVectIRQ
IRQSTATUS
RAWINTERRUPT INTSELECT [31:0]
[31:0] [31:0]

priority 0
vector interrupt 0
interrupt priority logic

VECTIRQ0 HARDWARE IRQ

PRIORITY nVICIRQ
LOGIC

address select
for
highest priority
SOURCE ENABLE VECTADDR VECTADDR0[31:0] interrupt
VECTCNTL[5:0] [31:0]

vector interrupt 1 priority1 VICVECT

VECTIRQ1 VECTADDR
[31:0] ADDROUT
VECTADDR1[31:0] [31:0]

priority2

vector interrupt 15 priority15 VECTIRQ15 DEFAULT

VECTADDR
VECTADDR15[31:0] [31:0]

nVICIRQIN VICVECTADDRIN[31:0]

Fig 16. Block diagram of the Vectored Interrupt Controller (VIC)

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7.6 Spurious interrupts

Spurious interrupts are possible in the ARM7TDMI based microcontrollers such as the
LPC213x due to asynchronous interrupt handling. The asynchronous character of the
interrupt processing has its roots in the interaction of the core and the VIC. If the VIC state
is changed between the moments when the core detects an interrupt, and the core
actually processes an interrupt, problems may be generated.

Real-life applications may experience the following scenarios:

1. VIC decides there is an IRQ interrupt and sends the IRQ signal to the core.
2. Core latches the IRQ state.
3. Processing continues for a few cycles due to pipelining.
4. Core loads IRQ address from VIC.

Furthermore, It is possible that the VIC state has changed during step 3. For example,
VIC was modified so that the interrupt that triggered the sequence starting with step 1) is
no longer pending -interrupt got disabled in the executed code. In this case, the VIC will
not be able to clearly identify the interrupt that generated the interrupt request, and as a
result the VIC will return the default interrupt VicDefVectAddr (0xFFFF F034).

This potentially disastrous chain of events can be prevented in two ways:

1. Application code should be set up in a way to prevent the spurious interrupts from
occurring. Simple guarding of changes to the VIC may not be enough since, for
example, glitches on level sensitive interrupts can also cause spurious interrupts.
2. VIC default handler should be set up and tested properly.

7.6.1 Details and case studies on spurious interrupts

This chapter contains details that can be obtained from the official ARM website, FAQ
section.

What happens if an interrupt occurs as it is being disabled?

Applies to: ARM7TDMI

If an interrupt is received by the core during execution of an instruction that disables

interrupts, the ARM7 family will still take the interrupt. This occurs for both IRQ and FIQ
interrupts.

For example, consider the following instruction sequence:

MRS r0, cpsr

ORR r0, r0, #I_Bit:OR:F_Bit ;disable IRQ and FIQ interrupts
MSR cpsr_c, r0

If an IRQ interrupt is received during execution of the MSR instruction, then the behavior
will be as follows:

• The IRQ interrupt is latched.

• The MSR cpsr, r0 executes to completion setting both the I bit and the F bit in the
CPSR.

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• The IRQ interrupt is taken because the core was committed to taking the interrupt
exception before the I bit was set in the CPSR.
• The CPSR (with the I bit and F bit set) is moved to the SPSR_IRQ.
This means that, on entry to the IRQ interrupt service routine, you can see the unusual
effect that an IRQ interrupt has just been taken while the I bit in the SPSR is set. In the
example above, the F bit will also be set in both the CPSR and SPSR. This means that
FIQs are disabled upon entry to the IRQ service routine, and will remain so until explicitly
re-enabled. FIQs will not be reenabled automatically by the IRQ return sequence.

Although the example shows both IRQ and FIQ interrupts being disabled, similar behavior
occurs when only one of the two interrupt types is being disabled. The fact that the core
processes the IRQ after completion of the MSR instruction which disables IRQs does not
normally cause a problem, since an interrupt arriving just one cycle earlier would be
expected to be taken. When the interrupt routine returns with an instruction like:

SUBS pc, lr, #4

the SPSR_IRQ is restored to the CPSR. The CPSR will now have the I bit and F bit set,
and therefore execution will continue with all interrupts disabled. However, this can cause
problems in the following cases:

Problem 1: A particular routine maybe called as an IRQ handler, or as a regular

subroutine. In the latter case, the system guarantees that IRQs would have been disabled
prior to the routine being called. The routine exploits this restriction to determine how it
was called (by examining the I bit of the SPSR), and returns using the appropriate
instruction. If the routine is entered due to an IRQ being received during execution of the
MSR instruction which disables IRQs, then the I bit in the SPSR will be set. The routine
would therefore assume that it could not have been entered via an IRQ.

Problem 2: FIQs and IRQs are both disabled by the same write to the CPSR. In this case,
if an IRQ is received during the CPSR write, FIQs will be disabled for the execution time of
the IRQ handler. This may not be acceptable in a system where FIQs must not be
disabled for more than a few cycles.

7.6.2 Workaround
There are 3 suggested workarounds. Which of these is most applicable will depend upon
the requirements of the particular system.

7.6.3 Solution 1: test for an IRQ received during a write to disable IRQs
Add code similar to the following at the start of the interrupt routine.

SUB lr, lr, #4 ; Adjust LR to point to return

STMFD sp!, {..., lr} ; Get some free regs
MRS lr, SPSR ; See if we got an interrupt while
TST lr, #I_Bit ; interrupts were disabled.
LDMNEFD sp!, {..., pc}^ ; If so, just return immediately.
; The interrupt will remain pending since we haven’t
; acknowledged it and will be reissued when interrupts
; are next enabled.
; Rest of interrupt routine

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This code will test for the situation where the IRQ was received during a write to disable
IRQs. If this is the case, the code returns immediately - resulting in the IRQ not being
acknowledged (cleared), and further IRQs being disabled.

Similar code may also be applied to the FIQ handler, in order to resolve the first issue.

This is the recommended workaround, as it overcomes both problems mentioned above.

However, in the case of problem two, it does add several cycles to the maximum length of
time FIQs will be disabled.

7.6.4 Solution 2: disable IRQs and FIQs using separate writes to the CPSR
MRS r0, cpsr
ORR r0, r0, #I_Bit ;disable IRQs
MSR cpsr_c, r0
ORR r0, r0, #F_Bit ;disable FIQs
MSR cpsr_c, r0

This is the best workaround where the maximum time for which FIQs are disabled is
critical (it does not increase this time at all). However, it does not solve problem one, and
requires extra instructions at every point where IRQs and FIQs are disabled together.

7.6.5 Solution 3: re-enable FIQs at the beginning of the IRQ handler

As the required state of all bits in the c field of the CPSR are known, this can be most
efficiently be achieved by writing an immediate value to CPSR_C, for example:

MSR cpsr_c, #I_Bit:OR:irq_MODE ;IRQ should be disabled

;FIQ enabled
;ARM state, IRQ mode

This requires only the IRQ handler to be modified, and FIQs may be re-enabled more
quickly than by using workaround 1. However, this should only be used if the system can
guarantee that FIQs are never disabled while IRQs are enabled. It does not address
problem one.

7.7 VIC usage notes

If user code is running from an on-chip RAM and an application uses interrupts, interrupt
vectors must be re-mapped to on-chip address 0x0. This is necessary because all the
exception vectors are located at addresses 0x0 and above. This is easily achieved by
configuring the MEMMAP register (see Section 4.7.1 “Memory Mapping control register
(MEMMAP - 0xE01F C040)” on page 32) to User RAM mode. Application code should be
linked such that at 0x4000 0000 the Interrupt Vector Table (IVT) will reside.

Although multiple sources can be selected (VICIntSelect) to generate FIQ request, only
one interrupt service routine should be dedicated to service all available/present FIQ
request(s). Therefore, if more than one interrupt sources are classified as FIQ the FIQ
interrupt service routine must read VICFIQStatus to decide based on this content what to
do and how to process the interrupt request. However, it is recommended that only one
interrupt source should be classified as FIQ. Classifying more than one interrupt sources
as FIQ will increase the interrupt latency.

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Following the completion of the desired interrupt service routine, clearing of the interrupt
flag on the peripheral level will propagate to corresponding bits in VIC registers
(VICRawIntr, VICFIQStatus and VICIRQStatus). Also, before the next interrupt can be
serviced, it is necessary that write is performed into the VICVectAddr register before the
return from interrupt is executed. This write will clear the respective interrupt flag in the
internal interrupt priority hardware.

In order to disable the interrupt at the VIC you need to clear corresponding bit in the
VICIntEnClr register, which in turn clears the related bit in the VICIntEnable register. This
also applies to the VICSoftInt and VICSoftIntClear in which VICSoftIntClear will clear the
respective bits in VICSoftInt. For example, if VICSoftInt = 0x0000 0005 and bit 0 has to be
cleared, VICSoftIntClear = 0x0000 0001 will accomplish this. Before the new clear
operation on the same bit in VICSoftInt using writing into VICSoftIntClear is performed in
the future, VICSoftIntClear = 0x0000 0000 must be assigned. Therefore writing 1 to any
bit in Clear register will have one-time-effect in the destination register.

If the watchdog is enabled for interrupt on underflow or invalid feed sequence only then
there is no way of clearing the interrupt. The only way you could perform return from
interrupt is by disabling the interrupt at the VIC (using VICIntEnClr).

Example:

Assuming that UART0 and SPI0 are generating interrupt requests that are classified as
vectored IRQs (UART0 being on the higher level than SPI0), while UART1 and I2C are
generating non-vectored IRQs, the following could be one possibility for VIC setup:

VICIntSelect = 0x0000 0000 ; SPI0, I2C, UART1 and UART0 are IRQ =>
; bit10, bit9, bit7 and bit6=0
VICIntEnable = 0x0000 06C0 ; SPI0, I2C, UART1 and UART0 are enabled interrupts =>
; bit10, bit9, bit 7 and bit6=1
VICDefVectAddr = 0x... ; holds address at what routine for servicing
; non-vectored IRQs (i.e. UART1 and I2C) starts
VICVectAddr0 = 0x... ; holds address where UART0 IRQ service routine starts
VICVectAddr1 = 0x... ; holds address where SPI0 IRQ service routine starts
VICVectCntl0 = 0x0000 0026 ; interrupt source with index 6 (UART0) is enabled as
; the one with priority 0 (the highest)
VICVectCntl1 = 0x0000 002A ; interrupt source with index 10 (SPI0) is enabled
; as the one with priority 1

After any of IRQ requests (SPI0, I2C, UART0 or UART1) is made, microcontroller will
redirect code execution to the address specified at location 0x0000 0018. For vectored
and non-vectored IRQ’s the following instruction could be placed at 0x0000 0018:

LDR pc, [pc,#-0xFF0]

This instruction loads PC with the address that is present in VICVectAddr register.

In case UART0 request has been made, VICVectAddr will be identical to VICVectAddr0,
while in case SPI0 request has been made value from VICVectAddr1 will be found here. If
neither UART0 nor SPI0 have generated IRQ request but UART1 and/or I2C were the
reason, content of VICVectAddr will be identical to VICDefVectAddr.

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8.1 Features
• Every physical GPIO port is accessible via either the group of registers providing an
enhanced features and accelerated port access or the legacy group of registers
• Accelerated GPIO functions available on LPC213x/01 include:
– GPIO registers are relocated to the ARM local bus so that the fastest possible I/O
timing can be achieved
– Mask registers allow treating sets of port bits as a group, leaving other bits
unchanged
– All registers are byte and half-word addressable
– Entire port value can be written in one instruction
• Bit-level set and clear registers allow a single instruction set or clear of any number of
bits in one port (LPC213x/01 only)
• Direction control of individual bits
• All I/O default to inputs after reset
• Backward compatibility with other earlier devices is maintained with legacy registers
appearing at the original addresses on the APB bus

8.2 Applications
• General purpose I/O
• Driving LEDs, or other indicators
• Controlling off-chip devices
• Sensing digital inputs

8.3 Pin description

Table 64. GPIO pin description
Pin Type Description
P0.0-P.31 Input/ General purpose input/output. The number of GPIOs actually available depends on the
P1.16-P1.31 Output use of alternate functions.

8.4 Register description

LPC213x has two 32-bit General Purpose I/O ports. Total of 30 input/output and a single
output only pin out of 32 pins are available on PORT0. PORT1 has up to 16 pins available
for GPIO functions. PORT0 and PORT1 are controlled via two groups of 4 registers as
shown in Table 65 and Table 66.

Legacy registers shown in Table 65 allow backward compatibility with earlier family
devices, using existing code. The functions and relative timing of older GPIO
implementations is preserved.
UM10120 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved.

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The registers in Table 66 represent the enhanced GPIO features available on the
LPC213x/01 only. All of these registers are located directly on the local bus of the CPU for
the fastest possible read and write timing. An additional feature has been added that
provides byte addressability of all GPIO registers. A mask register allows treating groups
of bits in a single GPIO port separately from other bits on the same port.

The user must select whether a GPIO will be accessed via registers that provide
enhanced features or a legacy set of registers (see Section 4.6.1 “System Control and
Status flags register (SCS - 0xE01F C1A0)” on page 31). While both of a port’s fast and
legacy GPIO registers are controlling the same physical pins, these two port control
branches are mutually exclusive and operate independently. For example, changing a
pin’s output via a fast register will not be observable via the corresponding legacy register.

The following text will refer to the legacy GPIO as "the slow" GPIO, while GPIO equipped
with the enhanced features will be referred as "the fast" GPIO.

Table 65. GPIO register map (legacy APB accessible registers)

Generic Description Access Reset PORT0 PORT1
Name value[1] Address & Name Address & Name
IOPIN GPIO Port Pin value register. The current R/W NA 0xE002 8000 0xE002 8010
state of the GPIO configured port pins can IO0PIN IO1PIN
always be read from this register, regardless
of pin direction.
IOSET GPIO Port Output Set register. This register R/W 0x0000 0000 0xE002 8004 0xE002 8014
controls the state of output pins in IO0SET IO1SET
conjunction with the IOCLR register. Writing
ones produces highs at the corresponding
port pins. Writing zeroes has no effect.
IODIR GPIO Port Direction control register. This R/W 0x0000 0000 0xE002 8008 0xE002 8018
register individually controls the direction of IO0DIR IO1DIR
each port pin.
IOCLR GPIO Port Output Clear register. This WO 0x0000 0000 0xE002 800C 0xE002 801C
register controls the state of output pins. IO0CLR IO1CLR
Writing ones produces lows at the
corresponding port pins and clears the
corresponding bits in the IOSET register.
Writing zeroes has no effect.

[1] Reset value reflects the data stored in used bits only. It does not include reserved bits content.

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Table 66. GPIO register map (local bus accessible registers - enhanced GPIO features on LPC213x/01 only)
Generic Description Access Reset PORT0 PORT1
Name value[1] Address & Name Address & Name
FIODIR Fast GPIO Port Direction control register. R/W 0x0000 0000 0x3FFF C000 0x3FFF C020
This register individually controls the FIO0DIR FIO1DIR
direction of each port pin.
FIOMASK Fast Mask register for port. Writes, sets, R/W 0x0000 0000 0x3FFF C010 0x3FFF C030
clears, and reads to port (done via writes to FIO0MASK FIO1MASK
FIOPIN, FIOSET, and FIOCLR, and reads of
FIOPIN) alter or return only the bits enabled
by zeros in this register.
FIOPIN Fast Port Pin value register using FIOMASK. R/W 0x0000 0000 0x3FFF C014 0x3FFF C034
The current state of digital port pins can be FIO0PIN FIO1PIN
read from this register, regardless of pin
direction or alternate function selection (as
long as pin is not configured as an input to
ADC). The value read is value of the
physical pins masked by ANDing the
inverted FIOMASK. Writing to this register
affects only port bits enabled by ZEROES in
FIOMASK.
FIOSET Fast Port Output Set register using R/W 0x0000 0000 0x3FFF C018 0x3FFF C038
FIOMASK. This register controls the state of FIO0SET FIO1SET
output pins. Writing 1s produces highs at the
corresponding port pins. Writing 0s has no
effect. Reading this register returns the
current contents of the port output register.
Only bits enabled by ZEROES in FIOMASK
can be altered.
FIOCLR Fast Port Output Clear register using WO 0x0000 0000 0x3FFF C01C 0x3FFF C03C
FIOMASK. This register controls the state of FIO0CLR FIO1CLR
output pins. Writing 1s produces lows at the
corresponding port pins. Writing 0s has no
effect. Only bits enabled by ZEROES in
FIOMASK can be altered.

[1] Reset value reflects the data stored in used bits only. It does not include reserved bits content.

8.4.1 GPIO port Direction register (IODIR, Port 0: IO0DIR - 0xE002 8008 and
Port 1: IO1DIR - 0xE002 8018; FIODIR, Port 0: FIO0DIR - 0x3FFF C000
and Port 1:FIO1DIR - 0x3FFF C020)
This word accessible register is used to control the direction of the pins when they are
configured as GPIO port pins. Direction bit for any pin must be set according to the pin
functionality.

Legacy registers are the IO0DIR and IO1DIR, while the enhanced GPIO functions are
supported via the FIO0DIR and FIO1DIR registers.

Table 67. GPIO port 0 Direction register (IO0DIR - address 0xE002 8008) bit description
Bit Symbol Value Description Reset value
31:0 P0xDIR Slow GPIO Direction control bits. Bit 0 controls P0.0 ... bit 30 controls P0.30. 0x0000 0000
0 Controlled pin is input.
1 Controlled pin is output.
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Table 68. GPIO port 1 Direction register (IO1DIR - address 0xE002 8018) bit description
Bit Symbol Value Description Reset value
31:0 P1xDIR Slow GPIO Direction control bits. Bit 0 in IO1DIR controls P1.0 ... Bit 30 in 0x0000 0000
IO1DIR controls P1.30.
0 Controlled pin is input.
1 Controlled pin is output.

Table 69. Fast GPIO port 0 Direction register (FIO0DIR - address 0x3FFF C000) bit description
Bit Symbol Value Description Reset value
31:0 FP0xDIR Fast GPIO Direction control bits. Bit 0 in FIO0DIR controls P0.0 ... Bit 30 in 0x0000 0000
FIO0DIR controls P0.30.
0 Controlled pin is input.
1 Controlled pin is output.

Table 70. Fast GPIO port 1 Direction register (FIO1DIR - address 0x3FFF C020) bit description
Bit Symbol Value Description Reset value
31:0 FP1xDIR Fast GPIO Direction control bits. Bit 0 in FIO1DIR controls P1.0 ... Bit 30 in 0x0000 0000
FIO1DIR controls P1.30.
0 Controlled pin is input.
1 Controlled pin is output.

Aside from the 32-bit long and word only accessible FIODIR register, every fast GPIO port
can also be controlled via several byte and half-word accessible registers listed in
Table 71 and Table 72, too. Next to providing the same functions as the FIODIR register,
these additional registers allow easier and faster access to the physical port pins.

Table 71. Fast GPIO port 0 Direction control byte and half-word accessible register description
Register Register Address Description Reset
name length (bits) value
& access
FIO0DIR0 8 (byte) 0x3FFF C000 Fast GPIO Port 0 Direction control register 0. Bit 0 in FIO0DIR0 0x00
register corresponds to P0.0 ... bit 7 to P0.7.
FIO0DIR1 8 (byte) 0x3FFF C001 Fast GPIO Port 0 Direction control register 1. Bit 0 in FIO0DIR1 0x00
register corresponds to P0.8 ... bit 7 to P0.15.
FIO0DIR2 8 (byte) 0x3FFF C002 Fast GPIO Port 0 Direction control register 2. Bit 0 in FIO0DIR2 0x00
register corresponds to P0.16 ... bit 7 to P0.23.
FIO0DIR3 8 (byte) 0x3FFF C003 Fast GPIO Port 0 Direction control register 3. Bit 0 in FIO0DIR3 0x00
register corresponds to P0.24 ... bit 7 to P0.31.
FIO0DIRL 16 0x3FFF C000 Fast GPIO Port 0 Direction control Lower half-word register. Bit 0 in 0x0000
(half-word) FIO0DIRL register corresponds to P0.0 ... bit 15 to P0.15.
FIO0DIRU 16 0x3FFF C002 Fast GPIO Port 0 Direction control Upper half-word register. Bit 0 in 0x0000
(half-word) FIO0DIRU register corresponds to P0.16 ... bit 15 to P0.31.

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Table 72. Fast GPIO port 1 Direction control byte and half-word accessible register description
Register Register Address Description Reset
name length (bits) value
& access
FIO1DIR0 8 (byte) 0x3FFF C020 Fast GPIO Port 1 Direction control register 0. Bit 0 in FIO1DIR0 0x00
register corresponds to P1.0 ... bit 7 to P1.7.
FIO1DIR1 8 (byte) 0x3FFF C021 Fast GPIO Port 1 Direction control register 1. Bit 0 in FIO1DIR1 0x00
register corresponds to P1.8 ... bit 7 to P1.15.
FIO1DIR2 8 (byte) 0x3FFF C022 Fast GPIO Port 1 Direction control register 2. Bit 0 in FIO1DIR2 0x00
register corresponds to P1.16 ... bit 7 to P1.23.
FIO1DIR3 8 (byte) 0x3FFF C023 Fast GPIO Port 1 Direction control register 3. Bit 0 in FIO1DIR3 0x00
register corresponds to P1.24 ... bit 7 to P1.31.
FIO1DIRL 16 0x3FFF C020 Fast GPIO Port 1 Direction control Lower half-word register. Bit 0 in 0x0000
(half-word) FIO1DIRL register corresponds to P1.0 ... bit 15 to P1.15.
FIO1DIRU 16 0x3FFF C022 Fast GPIO Port 1 Direction control Upper half-word register. Bit 0 in 0x0000
(half-word) FIO1DIRU register corresponds to P1.16 ... bit 15 to P1.31.

8.4.2 Fast GPIO port Mask register (FIOMASK, Port 0: FIO0MASK -

0x3FFF C010 and Port 1:FIO1MASK - 0x3FFF C030)
This register is available in the enhanced group of registers only. It is used to select port’s
pins that will and will not be affected by a write accesses to the FIOPIN, FIOSET or
FIOSLR register. Mask register also filters out port’s content when the FIOPIN register is
read.

A zero in this register’s bit enables an access to the corresponding physical pin via a read
or write access. If a bit in this register is one, corresponding pin will not be changed with
write access and if read, will not be reflected in the updated FIOPIN register. For software
examples, see Section 8.5 “GPIO usage notes” on page 90

Table 73. Fast GPIO port 0 Mask register (FIO0MASK - address 0x3FFF C010) bit description
Bit Symbol Value Description Reset value
31:0 FP0xMASK Fast GPIO physical pin access control. 0x0000 0000
0 Pin is affected by writes to the FIOSET, FIOCLR, and FIOPIN registers.
Current state of the pin will be observable in the FIOPIN register.
1 Physical pin is unaffected by writes into the FIOSET, FIOCLR and FIOPIN
registers. When the FIOPIN register is read, this bit will not be updated with
the state of the physical pin.

Table 74. Fast GPIO port 1 Mask register (FIO1MASK - address 0x3FFF C030) bit description
Bit Symbol Value Description Reset value
31:0 FP1xMASK Fast GPIO physical pin access control. 0x0000 0000
0 Pin is affected by writes to the FIOSET, FIOCLR, and FIOPIN registers.
Current state of the pin will be observable in the FIOPIN register.
1 Physical pin is unaffected by writes into the FIOSET, FIOCLR and FIOPIN
registers. When the FIOPIN register is read, this bit will not be updated with
the state of the physical pin.

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Aside from the 32-bit long and word only accessible FIOMASK register, every fast GPIO
port can also be controlled via several byte and half-word accessible registers listed in
Table 75 and Table 76, too. Next to providing the same functions as the FIOMASK
register, these additional registers allow easier and faster access to the physical port pins.

Table 75. Fast GPIO port 0 Mask byte and half-word accessible register description
Register Register Address Description Reset
name length (bits) value
& access
FIO0MASK0 8 (byte) 0x3FFF C010 Fast GPIO Port 0 Mask register 0. Bit 0 in FIO0MASK0 register 0x00
corresponds to P0.0 ... bit 7 to P0.7.
FIO0MASK1 8 (byte) 0x3FFF C011 Fast GPIO Port 0 Mask register 1. Bit 0 in FIO0MASK1 register 0x00
corresponds to P0.8 ... bit 7 to P0.15.
FIO0MASK2 8 (byte) 0x3FFF C012 Fast GPIO Port 0 Mask register 2. Bit 0 in FIO0MASK2 register 0x00
corresponds to P0.16 ... bit 7 to P0.23.
FIO0MASK3 8 (byte) 0x3FFF C013 Fast GPIO Port 0 Mask register 3. Bit 0 in FIO0MASK3 register 0x00
corresponds to P0.24 ... bit 7 to P0.31.
FIO0MASKL 16 0x3FFF C010 Fast GPIO Port 0 Mask Lower half-word register. Bit 0 in 0x0000
(half-word) FIO0MASKL register corresponds to P0.0 ... bit 15 to P0.15.
FIO0MASKU 16 0x3FFF C012 Fast GPIO Port 0 Mask Upper half-word register. Bit 0 in 0x0000
(half-word) FIO0MASKU register corresponds to P0.16 ... bit 15 to P0.31.

Table 76. Fast GPIO port 1 Mask byte and half-word accessible register description
Register Register Address Description Reset
name length (bits) value
& access
FIO1MASK0 8 (byte) 0x3FFF C010 Fast GPIO Port 1 Mask register 0. Bit 0 in FIO1MASK0 register 0x00
corresponds to P1.0 ... bit 7 to P1.7.
FIO1MASK1 8 (byte) 0x3FFF C011 Fast GPIO Port 1 Mask register 1. Bit 0 in FIO1MASK1 register 0x00
corresponds to P1.8 ... bit 7 to P1.15.
FIO1MASK2 8 (byte) 0x3FFF C012 Fast GPIO Port 1 Mask register 2. Bit 0 in FIO1MASK2 register 0x00
corresponds to P1.16 ... bit 7 to P1.23.
FIO1MASK3 8 (byte) 0x3FFF C013 Fast GPIO Port 1 Mask register 3. Bit 0 in FIO1MASK3 register 0x00
corresponds to P1.24 ... bit 7 to P1.31.
FIO1MASKL 16 0x3FFF C010 Fast GPIO Port 1 Mask Lower half-word register. Bit 0 in 0x0000
(half-word) FIO1MASKL register corresponds to P1.0 ... bit 15 to P1.15.
FIO1MASKU 16 0x3FFF C012 Fast GPIO Port 1 Mask Upper half-word register. Bit 0 in 0x0000
(half-word) FIO1MASKU register corresponds to P1.16 ... bit 15 to P1.31.

8.4.3 GPIO port Pin value register (IOPIN, Port 0: IO0PIN - 0xE002 8000 and
Port 1: IO1PIN - 0xE002 8010; FIOPIN, Port 0: FIO0PIN - 0x3FFF C014
and Port 1: FIO1PIN - 0x3FFF C034)
This register provides the value of port pins that are configured to perform only digital
functions. The register will give the logic value of the pin regardless of whether the pin is
configured for input or output, or as GPIO or an alternate digital function. As an example,
a particular port pin may have GPIO input, GPIO output, UART receive, and PWM output
as selectable functions. Any configuration of that pin will allow its current logic state to be
read from the IOPIN register.

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If a pin has an analog function as one of its options, the pin state cannot be read if the
analog configuration is selected. Selecting the pin as an A/D input disconnects the digital
features of the pin. In that case, the pin value read in the IOPIN register is not valid.

Writing to the IOPIN register stores the value in the port output register, bypassing the
need to use both the IOSET and IOCLR registers to obtain the entire written value. This
feature should be used carefully in an application since it affects the entire port.

Legacy registers are the IO0PIN and IO1PIN, while the enhanced GPIOs are supported
via the FIO0PIN and FIO1PIN registers. Access to a port pins via the FIOPIN register is
conditioned by the corresponding FIOMASK register (see Section 8.4.2 “Fast GPIO port
Mask register (FIOMASK, Port 0: FIO0MASK - 0x3FFF C010 and Port 1:FIO1MASK -
0x3FFF C030)”).

Only pins masked with zeros in the Mask register (see Section 8.4.2 “Fast GPIO port
Mask register (FIOMASK, Port 0: FIO0MASK - 0x3FFF C010 and Port 1:FIO1MASK -
0x3FFF C030)”) will be correlated to the current content of the Fast GPIO port pin value
register.

Table 77. GPIO port 0 Pin value register (IO0PIN - address 0xE002 8000) bit description
Bit Symbol Description Reset value
31:0 P0xVAL Slow GPIO pin value bits. Bit 0 in IO0PIN corresponds to P0.0 ... Bit 31 in IO0PIN NA
corresponds to P0.31.

Table 78. GPIO port 1 Pin value register (IO1PIN - address 0xE002 8010) bit description
Bit Symbol Description Reset value
31:0 P1xVAL Slow GPIO pin value bits. Bit 0 in IO1PIN corresponds to P1.0 ... Bit 31 in IO1PIN NA
corresponds to P1.31.

Table 79. Fast GPIO port 0 Pin value register (FIO0PIN - address 0x3FFF C014) bit description
Bit Symbol Description Reset value
31:0 FP0xVAL Fast GPIO pin value bits. Bit 0 in FIO0PIN corresponds to P0.0 ... Bit 31 in FIO0PIN NA
corresponds to P0.31.

Table 80. Fast GPIO port 1 Pin value register (FIO1PIN - address 0x3FFF C034) bit description
Bit Symbol Description Reset value
31:0 FP1xVAL Fast GPIO pin value bits. Bit 0 in FIO1PIN corresponds to P1.0 ... Bit 31 in FIO1PIN NA
corresponds to P1.31.

Aside from the 32-bit long and word only accessible FIOPIN register, every fast GPIO port
can also be controlled via several byte and half-word accessible registers listed in
Table 81 and Table 82, too. Next to providing the same functions as the FIOPIN register,
these additional registers allow easier and faster access to the physical port pins.

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Table 81. Fast GPIO port 0 Pin value byte and half-word accessible register description
Register Register Address Description Reset
name length (bits) value
& access
FIO0PIN0 8 (byte) 0x3FFF C014 Fast GPIO Port 0 Pin value register 0. Bit 0 in FIO0PIN0 register 0x00
corresponds to P0.0 ... bit 7 to P0.7.
FIO0PIN1 8 (byte) 0x3FFF C015 Fast GPIO Port 0 Pin value register 1. Bit 0 in FIO0PIN1 register 0x00
corresponds to P0.8 ... bit 7 to P0.15.
FIO0PIN2 8 (byte) 0x3FFF C016 Fast GPIO Port 0 Pin value register 2. Bit 0 in FIO0PIN2 register 0x00
corresponds to P0.16 ... bit 7 to P0.23.
FIO0PIN3 8 (byte) 0x3FFF C017 Fast GPIO Port 0 Pin value register 3. Bit 0 in FIO0PIN3 register 0x00
corresponds to P0.24 ... bit 7 to P0.31.
FIO0PINL 16 0x3FFF C014 Fast GPIO Port 0 Pin value Lower half-word register. Bit 0 in 0x0000
(half-word) FIO0PINL register corresponds to P0.0 ... bit 15 to P0.15.
FIO0PINU 16 0x3FFF C016 Fast GPIO Port 0 Pin value Upper half-word register. Bit 0 in 0x0000
(half-word) FIO0PINU register corresponds to P0.16 ... bit 15 to P0.31.

Table 82. Fast GPIO port 1 Pin value byte and half-word accessible register description
Register Register Address Description Reset
name length (bits) value
& access
FIO1PIN0 8 (byte) 0x3FFF C034 Fast GPIO Port 1 Pin value register 0. Bit 0 in FIO1PIN0 register 0x00
corresponds to P1.0 ... bit 7 to P1.7.
FIO1PIN1 8 (byte) 0x3FFF C035 Fast GPIO Port 1 Pin value register 1. Bit 0 in FIO1PIN1 register 0x00
corresponds to P1.8 ... bit 7 to P1.15.
FIO1PIN2 8 (byte) 0x3FFF C036 Fast GPIO Port 1 Pin value register 2. Bit 0 in FIO1PIN2 register 0x00
corresponds to P1.16 ... bit 7 to P1.23.
FIO1PIN3 8 (byte) 0x3FFF C037 Fast GPIO Port 1 Pin value register 3. Bit 0 in FIO1PIN3 register 0x00
corresponds to P1.24 ... bit 7 to P1.31.
FIO1PINL 16 0x3FFF C034 Fast GPIO Port 1 Pin value Lower half-word register. Bit 0 in 0x0000
(half-word) FIO1PINL register corresponds to P1.0 ... bit 15 to P1.15.
FIO1PINU 16 0x3FFF C036 Fast GPIO Port 1 Pin value Upper half-word register. Bit 0 in 0x0000
(half-word) FIO1PINU register corresponds to P1.16 ... bit 15 to P1.31.

8.4.4 GPIO port output Set register (IOSET, Port 0: IO0SET - 0xE002 8004
and Port 1: IO1SET - 0xE002 8014; FIOSET, Port 0: FIO0SET -
0x3FFF C018 and Port 1: FIO1SET - 0x3FFF C038)
This register is used to produce a HIGH level output at the port pins configured as GPIO in
an OUTPUT mode. Writing 1 produces a HIGH level at the corresponding port pins.
Writing 0 has no effect. If any pin is configured as an input or a secondary function, writing
1 to the corresponding bit in the IOSET has no effect.

Reading the IOSET register returns the value of this register, as determined by previous
writes to IOSET and IOCLR (or IOPIN as noted above). This value does not reflect the
effect of any outside world influence on the I/O pins.

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Legacy registers are the IO0SET and IO1SET, while the enhanced GPIOs are supported
via the FIO0SET and FIO1SET registers. Access to a port pins via the FIOSET register is
conditioned by the corresponding FIOMASK register (see Section 8.4.2 “Fast GPIO port
Mask register (FIOMASK, Port 0: FIO0MASK - 0x3FFF C010 and Port 1:FIO1MASK -
0x3FFF C030)”).

Table 83. GPIO port 0 output Set register (IO0SET - address 0xE002 8004 bit description
Bit Symbol Description Reset value
31:0 P0xSET Slow GPIO output value Set bits. Bit 0 in IO0SET corresponds to P0.0 ... Bit 31 0x0000 0000
in IO0SET corresponds to P0.31.

Table 84. GPIO port 1 output Set register (IO1SET - address 0xE002 8014) bit description
Bit Symbol Description Reset value
31:0 P1xSET Slow GPIO output value Set bits. Bit 0 in IO1SET corresponds to P1.0 ... Bit 31 0x0000 0000
in IO1SET corresponds to P1.31.

Table 85. Fast GPIO port 0 output Set register (FIO0SET - address 0x3FFF C018) bit description
Bit Symbol Description Reset value
31:0 FP0xSET Fast GPIO output value Set bits. Bit 0 in FIO0SET corresponds to P0.0 ... Bit 31 0x0000 0000
in FIO0SET corresponds to P0.31.

Table 86. Fast GPIO port 1 output Set register (FIO1SET - address 0x3FFF C038) bit description
Bit Symbol Description Reset value
31:0 FP1xSET Fast GPIO output value Set bits. Bit 0 Fin IO1SET corresponds to P1.0 ... Bit 0x0000 0000
31 in FIO1SET corresponds to P1.31.

Aside from the 32-bit long and word only accessible FIOSET register, every fast GPIO
port can also be controlled via several byte and half-word accessible registers listed in
Table 87 and Table 88, too. Next to providing the same functions as the FIOSET register,
these additional registers allow easier and faster access to the physical port pins.

Table 87. Fast GPIO port 0 output Set byte and half-word accessible register description
Register Register Address Description Reset
name length (bits) value
& access
FIO0SET0 8 (byte) 0x3FFF C018 Fast GPIO Port 0 output Set register 0. Bit 0 in FIO0SET0 register 0x00
corresponds to P0.0 ... bit 7 to P0.7.
FIO0SET1 8 (byte) 0x3FFF C019 Fast GPIO Port 0 output Set register 1. Bit 0 in FIO0SET1 register 0x00
corresponds to P0.8 ... bit 7 to P0.15.
FIO0SET2 8 (byte) 0x3FFF C01A Fast GPIO Port 0 output Set register 2. Bit 0 in FIO0SET2 register 0x00
corresponds to P0.16 ... bit 7 to P0.23.
FIO0SET3 8 (byte) 0x3FFF C01B Fast GPIO Port 0 output Set register 3. Bit 0 in FIO0SET3 register 0x00
corresponds to P0.24 ... bit 7 to P0.31.
FIO0SETL 16 0x3FFF C018 Fast GPIO Port 0 output Set Lower half-word register. Bit 0 in 0x0000
(half-word) FIO0SETL register corresponds to P0.0 ... bit 15 to P0.15.
FIO0SETU 16 0x3FFF C01A Fast GPIO Port 0 output Set Upper half-word register. Bit 0 in 0x0000
(half-word) FIO0SETU register corresponds to P0.16 ... bit 15 to P0.31.

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Table 88. Fast GPIO port 1 output Set byte and half-word accessible register description
Register Register Address Description Reset
name length (bits) value
& access
FIO1SET0 8 (byte) 0x3FFF C038 Fast GPIO Port 1 output Set register 0. Bit 0 in FIO1SET0 register 0x00
corresponds to P1.0 ... bit 7 to P1.7.
FIO1SET1 8 (byte) 0x3FFF C039 Fast GPIO Port 1 output Set register 1. Bit 0 in FIO1SET1 register 0x00
corresponds to P1.8 ... bit 7 to P1.15.
FIO1SET2 8 (byte) 0x3FFF C03A Fast GPIO Port 1 output Set register 2. Bit 0 in FIO1SET2 register 0x00
corresponds to P1.16 ... bit 7 to P1.23.
FIO1SET3 8 (byte) 0x3FFF C03B Fast GPIO Port 1 output Set register 3. Bit 0 in FIO1SET3 register 0x00
corresponds to P1.24 ... bit 7 to P1.31.
FIO1SETL 16 0x3FFF C038 Fast GPIO Port 1 output Set Lower half-word register. Bit 0 in 0x0000
(half-word) FIO1SETL register corresponds to P1.0 ... bit 15 to P1.15.
FIO1SETU 16 0x3FFF C03A Fast GPIO Port 1 output Set Upper half-word register. Bit 0 in 0x0000
(half-word) FIO1SETU register corresponds to P1.16 ... bit 15 to P1.31.

8.4.5 GPIO port output Clear register (IOCLR, Port 0: IO0CLR -

0xE002 800C and Port 1: IO1CLR - 0xE002 801C; FIOCLR, Port 0:
FIO0CLR - 0x3FFF C01C and Port 1: FIO1CLR - 0x3FFF C03C)
This register is used to produce a LOW level output at port pins configured as GPIO in an
OUTPUT mode. Writing 1 produces a LOW level at the corresponding port pin and clears
the corresponding bit in the IOSET register. Writing 0 has no effect. If any pin is configured
as an input or a secondary function, writing to IOCLR has no effect.

Legacy registers are the IO0CLR and IO1CLR, while the enhanced GPIOs are supported
via the FIO0CLR and FIO1CLR registers. Access to a port pins via the FIOCLR register is
conditioned by the corresponding FIOMASK register (see Section 8.4.2 “Fast GPIO port
Mask register (FIOMASK, Port 0: FIO0MASK - 0x3FFF C010 and Port 1:FIO1MASK -
0x3FFF C030)”).

Table 89. GPIO port 0 output Clear register 0 (IO0CLR - address 0xE002 800C) bit description
Bit Symbol Description Reset value
31:0 P0xCLR Slow GPIO output value Clear bits. Bit 0 in IO0CLR corresponds to P0.0 ... Bit 0x0000 0000
31 in IO0CLR corresponds to P0.31.

Table 90. GPIO port 1 output Clear register 1 (IO1CLR - address 0xE002 801C) bit description
Bit Symbol Description Reset value
31:0 P1xCLR Slow GPIO output value Clear bits. Bit 0 in IO1CLR corresponds to P1.0 ... Bit 0x0000 0000
31 in IO1CLR corresponds to P1.31.

Table 91. Fast GPIO port 0 output Clear register 0 (FIO0CLR - address 0x3FFF C01C) bit description
Bit Symbol Description Reset value
31:0 FP0xCLR Fast GPIO output value Clear bits. Bit 0 in FIO0CLR corresponds to P0.0 ... Bit 0x0000 0000
31 in FIO0CLR corresponds to P0.31.

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Table 92. Fast GPIO port 1 output Clear register 1 (FIO1CLR - address 0x3FFF C03C) bit description
Bit Symbol Description Reset value
31:0 FP1xCLR Fast GPIO output value Clear bits. Bit 0 in FIO1CLR corresponds to P1.0 ... Bit 0x0000 0000
31 in FIO1CLR corresponds to P1.31.

Aside from the 32-bit long and word only accessible FIOCLR register, every fast GPIO
port can also be controlled via several byte and half-word accessible registers listed in
Table 93 and Table 94, too. Next to providing the same functions as the FIOCLR register,
these additional registers allow easier and faster access to the physical port pins.

Table 93. Fast GPIO port 0 output Clear byte and half-word accessible register description
Register Register Address Description Reset
name length (bits) value
& access
FIO0CLR0 8 (byte) 0x3FFF C01C Fast GPIO Port 0 output Clear register 0. Bit 0 in FIO0CLR0 register 0x00
corresponds to P0.0 ... bit 7 to P0.7.
FIO0CLR1 8 (byte) 0x3FFF C01D Fast GPIO Port 0 output Clear register 1. Bit 0 in FIO0CLR1 register 0x00
corresponds to P0.8 ... bit 7 to P0.15.
FIO0CLR2 8 (byte) 0x3FFF C01E Fast GPIO Port 0 output Clear register 2. Bit 0 in FIO0CLR2 register 0x00
corresponds to P0.16 ... bit 7 to P0.23.
FIO0CLR3 8 (byte) 0x3FFF C01F Fast GPIO Port 0 output Clear register 3. Bit 0 in FIO0CLR3 register 0x00
corresponds to P0.24 ... bit 7 to P0.31.
FIO0CLRL 16 0x3FFF C01C Fast GPIO Port 0 output Clear Lower half-word register. Bit 0 in 0x0000
(half-word) FIO0CLRL register corresponds to P0.0 ... bit 15 to P0.15.
FIO0CLRU 16 0x3FFF C01E Fast GPIO Port 0 output Clear Upper half-word register. Bit 0 in 0x0000
(half-word) FIO0SETU register corresponds to P0.16 ... bit 15 to P0.31.

Table 94. Fast GPIO port 1 output Clear byte and half-word accessible register description
Register Register Address Description Reset
name length (bits) value
& access
FIO1CLR0 8 (byte) 0x3FFF C03C Fast GPIO Port 1 output Clear register 0. Bit 0 in FIO1CLR0 register 0x00
corresponds to P1.0 ... bit 7 to P1.7.
FIO1CLR1 8 (byte) 0x3FFF C03D Fast GPIO Port 1 output Clear register 1. Bit 0 in FIO1CLR1 register 0x00
corresponds to P1.8 ... bit 7 to P1.15.
FIO1CLR2 8 (byte) 0x3FFF C03E Fast GPIO Port 1 output Clear register 2. Bit 0 in FIO1CLR2 register 0x00
corresponds to P1.16 ... bit 7 to P1.23.
FIO1CLR3 8 (byte) 0x3FFF C03F Fast GPIO Port 1 output Clear register 3. Bit 0 in FIO1CLR3 register 0x00
corresponds to P1.24 ... bit 7 to P1.31.
FIO1CLRL 16 0x3FFF C03C Fast GPIO Port 1 output Clear Lower half-word register. Bit 0 in 0x0000
(half-word) FIO1CLRL register corresponds to P1.0 ... bit 15 to P1.15.
FIO1CLRU 16 0x3FFF C03E Fast GPIO Port 1 output Clear Upper half-word register. Bit 0 in 0x0000
(half-word) FIO1CLRU register corresponds to P1.16 ... bit 15 to P1.31.

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8.5 GPIO usage notes

8.5.1 Example 1: sequential accesses to IOSET and IOCLR affecting the

same GPIO pin/bit
State of the output configured GPIO pin is determined by writes into the pin’s port IOSET
and IOCLR registers. Last of these accesses to the IOSET/IOCLR register will determine
the final output of a pin.

In case of a code:

IO0DIR = 0x0000 0080 ;pin P0.7 configured as output

IO0CLR = 0x0000 0080 ;P0.7 goes LOW
IO0SET = 0x0000 0080 ;P0.7 goes HIGH
IO0CLR = 0x0000 0080 ;P0.7 goes LOW

pin P0.7 is configured as an output (write to IO0DIR register). After this, P0.7 output is set
to low (first write to IO0CLR register). Short high pulse follows on P0.7 (write access to
IO0SET), and the final write to IO0CLR register sets pin P0.7 back to low level.

8.5.2 Example 2: an immediate output of 0s and 1s on a GPIO port

Write access to port’s IOSET followed by write to the IOCLR register results with pins
outputting 0s being slightly later then pins outputting 1s. There are systems that can
tolerate this delay of a valid output, but for some applications simultaneous output of a
binary content (mixed 0s and 1s) within a group of pins on a single GPIO port is required.
This can be accomplished by writing to the port’s IOPIN register.

Following code will preserve existing output on PORT0 pins P0.[31:16] and P0.[7:0] and
at the same time set P0.[15:8] to 0xA5, regardless of the previous value of pins P0.[15:8]:

IO0PIN = (IO0PIN && 0xFFFF00FF) || 0x0000A500

The same outcome can be obtained using the fast port access.

Solution 1: using 32-bit (word) accessible fast GPIO registers

FIO0MASK = 0xFFFF00FF;
FIO0PIN = 0x0000A500;

Solution 2: using 16-bit (half-word) accessible fast GPIO registers

FIO0MASKL = 0x00FF;
FIO0PINL = 0xA500;

Solution 3: using 8-bit (byte) accessible fast GPIO registers

FIO0PIN1 = 0xA5;

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8.5.3 Writing to IOSET/IOCLR vs IOPIN

Write to the IOSET/IOCLR register allows easy change of the port’s selected output pin(s)
to high/low level at a time. Only pin/bit(s) in the IOSET/IOCLR written with 1 will be set to
high/low level, while those written as 0 will remain unaffected. However, by just writing to
either IOSET or IOCLR register it is not possible to instantaneously output arbitrary binary
data containing mixture of 0s and 1s on a GPIO port.

Write to the IOPIN register enables instantaneous output of a desired content on the
parallel GPIO. Binary data written into the IOPIN register will affect all output configured
pins of that parallel port: 0s in the IOPIN will produce low level pin outputs and 1s in IOPIN
will produce high level pin outputs. In order to change output of only a group of port’s pins,
application must logically AND readout from the IOPIN with mask containing 0s in bits
corresponding to pins that will be changed, and 1s for all others. Finally, this result has to
be logically ORred with the desired content and stored back into the IOPIN register.
Example 2 from above illustrates output of 0xA5 on PORT0 pins 15 to 8 while preserving
all other PORT0 output pins as they were before.

8.5.4 Output signal frequency considerations when using the legacy and
enhanced GPIO registers
The enhanced features of the fast GPIO ports available on this microcontroller make
GPIO pins more responsive to the code that has task of controlling them. In particular,
software access to a GPIO pin is 3.5 times faster via the fast GPIO registers than it is
when the legacy set of registers is used. As a result of the access speed increase, the
maximum output frequency of the digital pin is increased 3.5 times, too. This tremendous
increase of the output frequency is not always that visible when a plain C code is used,
and a portion of an application handling the fast port output might have to be written in an
assembly code and executed in the ARM mode.

Here is a code where the pin control section is written in assembly language for ARM. It
illustrates the difference between the fast and slow GPIO port output capabilities. Once
this code is compiled in the ARM mode, its execution from the on-chip Flash will yield the
best results when the MAM module is configured as described in Section 3.9 “MAM usage
notes” on page 21. Execution from the on-chip SRAM is independent from the MAM
setup.

ldr r0,=0xe01fc1a0 /register address--enable fast port/

mov r1,#0x1
str r1,[r0] /*enable fast port0*/
ldr r1,=0xffffffff
ldr r0,=0x3fffc000 /*direction of fast port0*/
str r1,[r0]
ldr r0,=0xe0028018 /*direction of slow port 1*/
str r1,[r0]
ldr r0,=0x3fffc018 /*FIO0SET -- fast port0 register*/
ldr r1,=0x3fffc01c /*FIO0CLR0 -- fast port0 register*/
ldr r2,=0xC0010000 /*select fast port 0.16 for toggle*/
ldr r3,=0xE0028014 /*IO1SET -- slow port1 register*/
ldr r4,=0xE002801C /*IO1CLR -- slow port1 register*/
ldr r5,=0x00100000 /*select slow port 1.20 for toggle*/
/*Generate 2 pulses on the fast port*/
str r2,[r0]
UM10120 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved.

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str r2,[r1]
str r2,[r0]
str r2,[r1]
/*Generate 2 pulses on the slow port*/
str r5,[r3]
str r5,[r4]
str r5,[r3]
str r5,[r4]
loop: b loop

Figure 17 illustrates the code from above executed from the LPC213x/01 Flash memory.
The PLL generated FCCLK =60 MHz out of external FOSC = 12 MHz. The MAM was fully
enabled with MEMCR = 2 and MEMTIM = 3, and APBDIV = 1 (PCLK = CCLK).

Fig 17. Illustration of the fast and slow GPIO access and output showing 3.5 x increase of the pin output
frequency

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Chapter 9: LPC213x UART0
Rev. 3 — 4 October 2010 User manual

9.1 Features
• 16 byte Receive and Transmit FIFOs
• Register locations conform to ‘550 industry standard.
• Receiver FIFO trigger points at 1, 4, 8, and 14 bytes.
• Mechanism that enables software and hardware flow control implementation.

9.1.1 Enhancements introduced with LPC213x/01 devices

Powerful Fractional baud rate generator with autobauding capabilities provides standard
baud rates such as 115200 with any crystal frequency above 2 MHz.

9.2 Pin description

Table 95: UART0 pin description
Pin Type Description
RXD0 Input Serial Input. Serial receive data.
TXD0 Output Serial Output. Serial transmit data.

9.3 Register description

UART0 contains registers organized as shown in Table 96. The Divisor Latch Access Bit
(DLAB) is contained in U0LCR[7] and enables access to the Divisor Latches.

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NXP Semiconductors
Table 96: UART0 register map
Name Description Bit functions and addresses Access Reset Address
MSB LSB value[1]

BIT7 BIT6 BIT5 BIT4 BIT3 BIT2 BIT1 BIT0

U0RBR Receiver Buffer 8-bit Read Data RO NA 0xE000 C000
Register (DLAB=0)
U0THR Transmit Holding 8-bit Write Data WO NA 0xE000 C000
Register (DLAB=0)
U0DLL Divisor Latch LSB 8-bit Data R/W 0x01 0xE000 C000
(DLAB=1)
U0DLM Divisor Latch MSB 8-bit Data R/W 0x00 0xE000 C004
(DLAB=1)
U0IER Interrupt Enable - - - - - - En.ABTO En.ABEO R/W 0x00 0xE000 C004
All information provided in this document is subject to legal disclaimers.

Register [2] [2] (DLAB=0)

- - - - - En.RX Enable En.RxDat
Rev. 3 — 4 October 2010

Lin.St.Int THRE Int Av.Int

U0IIR Interrupt ID Reg. - - - - - - ABTO ABEO RO 0x01 0xE000 C008
Int[2] Int[2]
FIFOs Enabled - - IIR3 IIR2 IIR1 IIR0
U0FCR FIFO Control RX Trigger - - - TX FIFO RX FIFO FIFO WO 0x00 0xE000 C008
Register Reset Reset Enable
U0LCR Line Control DLAB Set Stick Even Parity No. of Word Length Select R/W 0x00 0xE000 C00C
Register Break Parity Par.Selct. Enable Stop Bits
U0LSR Line Status RX FIFO TEMT THRE BI FE PE OE DR RO 0x60 0xE000 C014
Register Error
U0SCR Scratch Pad Reg. 8-bit Data R/W 0x00 0xE000 C01C
U0ACR Auto-baud Control - - - - - - ABTO ABEO R/W 0x00 0xE000 C020
Register[2] Int.Clr Int.Clr

Chapter 9: LPC213x UART0

- - - - - Aut.Rstrt. Mode Start
U0FDR Fractional Divider Reserved[31:8] 0x10 0xE000 C028
Register[2] MulVal DivAddVal

UM10120
© NXP B.V. 2010. All rights reserved.

U0TER TX. Enable Reg. TXEN - - - - - - - R/W 0x80 0xE000 C030

[1] Reset value reflects the data stored in used bits only. It does not include reserved bits content.
[2] LPC213x/01 devices only.
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9.3.1 UART0 Receiver Buffer Register (U0RBR - 0xE000 C000, when

DLAB = 0, Read Only)
The U0RBR is the top byte of the UART0 Rx FIFO. The top byte of the Rx FIFO contains
the oldest character received and can be read via the bus interface. The LSB (bit 0)
represents the “oldest” received data bit. If the character received is less than 8 bits, the
unused MSBs are padded with zeroes.

The Divisor Latch Access Bit (DLAB) in U0LCR must be zero in order to access the
U0RBR. The U0RBR is always Read Only.

Since PE, FE and BI bits correspond to the byte sitting on the top of the RBR FIFO (i.e.
the one that will be read in the next read from the RBR), the right approach for fetching the
valid pair of received byte and its status bits is first to read the content of the U0LSR
register, and then to read a byte from the U0RBR.

Table 97: UART0 Receiver Buffer Register (U0RBR - address 0xE000 C000, when DLAB = 0,
Read Only) bit description
Bit Symbol Description Reset value
7:0 RBR The UART0 Receiver Buffer Register contains the oldest undefined
received byte in the UART0 Rx FIFO.

9.3.2 UART0 Transmit Holding Register (U0THR - 0xE000 C000, when

DLAB = 0, Write Only)
The U0THR is the top byte of the UART0 TX FIFO. The top byte is the newest character in
the TX FIFO and can be written via the bus interface. The LSB represents the first bit to
transmit.

The Divisor Latch Access Bit (DLAB) in U0LCR must be zero in order to access the
U0THR. The U0THR is always Write Only.

Table 98: UART0 Transmit Holding Register (U0THR - address 0xE000 C000, when
DLAB = 0, Write Only) bit description
Bit Symbol Description Reset value
7:0 THR Writing to the UART0 Transmit Holding Register causes the data NA
to be stored in the UART0 transmit FIFO. The byte will be sent
when it reaches the bottom of the FIFO and the transmitter is
available.

9.3.3 UART0 Divisor Latch Registers (U0DLL - 0xE000 C000 and U0DLM -
0xE000 C004, when DLAB = 1)
The UART0 Divisor Latch is part of the UART0 Fractional Baud Rate Generator and holds
the value used to divide the clock supplied by the fractional prescaler in order to produce
the baud rate clock, which must be 16x the desired baud rate (Equation 1). The U0DLL
and U0DLM registers together form a 16 bit divisor where U0DLL contains the lower 8 bits
of the divisor and U0DLM contains the higher 8 bits of the divisor. A 0x0000 value is
treated like a 0x0001 value as division by zero is not allowed.The Divisor Latch Access Bit
(DLAB) in U0LCR must be one in order to access the UART0 Divisor Latches.

Details on how to select the right value for U0DLL and U0DLM can be found later on in
this chapter.

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Table 99: UART0 Divisor Latch LSB register (U0DLL - address 0xE000 C000, when
DLAB = 1) bit description
Bit Symbol Description Reset value
7:0 DLL The UART0 Divisor Latch LSB Register, along with the U0DLM 0x01
register, determines the baud rate of the UART0.

Table 100: UART0 Divisor Latch MSB register (U0DLM - address 0xE000 C004, when
DLAB = 1) bit description
Bit Symbol Description Reset value
7:0 DLM The UART0 Divisor Latch MSB Register, along with the U0DLL 0x00
register, determines the baud rate of the UART0.

9.3.4 UART0 Fractional Divider Register (U0FDR - 0xE000 C028)

This register is available in LPC213x/01 devices only.

The UART0 Fractional Divider Register (U0FDR) controls the clock pre-scaler for the
baud rate generation and can be read and written at user’s discretion. This pre-scaler
takes the APB clock and generates an output clock per specified fractional requirements.

Important: If the fractional divider is active (DIVADDVAL > 0) and DLM = 0, the value of
the DLL register must be 3 or greater.

Table 101: UART0 Fractional Divider Register (U0FDR - address 0xE000 C028) bit description
Bit Function Description Reset value
3:0 DIVADDVAL Baudrate generation pre-scaler divisor value. If this field is 0, 0
fractional baudrate generator will not impact the UART0
baudrate.
7:4 MULVAL Baudrate pre-scaler multiplier value. This field must be greater 1
or equal 1 for UART0 to operate properly, regardless of
whether the fractional baudrate generator is used or not.
31:8 - Reserved, user software should not write ones to reserved bits. NA
The value read from a reserved bit is not defined.

This register controls the clock pre-scaler for the baud rate generation. The reset value of
the register keeps the fractional capabilities of UART0 disabled making sure that UART0
is fully software and hardware compatible with UARTs not equipped with this feature.

UART0 baudrate can be calculated as:

(1)

PCLK
UART0 baudrate = ----------------------------------------------------------------------------------------------------------------------------------
16 × ( 256 × U0DLM + U0DLL ) × ⎛⎝ 1 + -----------------------------⎞⎠
DivAddVal
MulVal

Where PCLK is the peripheral clock, U0DLM and U0DLL are the standard UART0 baud
rate divider registers, and DIVADDVAL and MULVAL are UART0 fractional baudrate
generator specific parameters.

The value of MULVAL and DIVADDVAL should comply to the following conditions:

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1. 0 < MULVAL ≤ 15
2. 0 ≤ DIVADDVAL ≤ 15

If the U0FDR register value does not comply to these two requests then the fractional
divider output is undefined. If DIVADDVAL is zero then the fractional divider is disabled
and the clock will not be divided.

The value of the U0FDR should not be modified while transmitting/receiving data or data
may be lost or corrupted.

Usage Note: For practical purposes, UART0 baudrate formula can be written in a way
that identifies the part of a UART baudrate generated without the fractional baudrate
generator, and the correction factor that this module adds:

(2)

PCLK MulVal
UART0 baudrate = -------------------------------------------------------------------------------- × ------------------------------------------------------------
16 × ( 256 × U0DLM + U0DLL ) ( MulVal + DivAddVal )

Based on this representation, fractional baudrate generator contribution can also be

described as a prescaling with a factor of MULVAL / (MULVAL + DIVADDVAL).

9.3.5 UART0 baudrate calculation

Example 1: Using UART0baudrate formula from above, it can be determined that system
with PCLK = 20 MHz, U0DL = 130 (U0DLM = 0x00 and U0DLL = 0x82), DIVADDVAL = 0
and MULVAL = 1 will enable UART0 with UART0baudrate = 9615 bauds.

Example 2: Using UART0baudrate formula from above, it can be determined that system
with PCLK = 20 MHz, U0DL = 93 (U0DLM = 0x00 and U0DLL = 0x5D), DIVADDVAL = 2
and MULVAL = 5 will enable UART0 with UART0baudrate = 9600 bauds.

Table 102: Baudrates available when using 20 MHz peripheral clock (PCLK = 20 MHz)
Desired MULVAL = 0 DIVADDVAL = 0 Optimal MULVAL & DIVADDVAL
baudrate U0DLM:U0DLL % error[3] U0DLM:U0DLL Fractional % error[3]
hex[2] dec[1] dec[1] pre-scaler value
MULDIV
MULDIV + DIVADDVAL

50 61A8 25000 0.0000 25000 1/(1+0) 0.0000

75 411B 16667 0.0020 12500 3/(3+1) 0.0000
110 2C64 11364 0.0032 6250 11/(11+9) 0.0000
134.5 244E 9294 0.0034 3983 3/(3+4) 0.0001
150 208D 8333 0.0040 6250 3/(3+1) 0.0000
300 1047 4167 0.0080 3125 3/(3+1) 0.0000
600 0823 2083 0.0160 1250 3/(3+2) 0.0000
1200 0412 1042 0.0320 625 3/(3+2) 0.0000
1800 02B6 694 0.0640 625 9/(9+1) 0.0000
2000 0271 625 0.0000 625 1/(1+0) 0.0000

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2400 0209 521 0.0320 250 12/(12+13) 0.0000

3600 015B 347 0.0640 248 5/(5+2) 0.0064
4800 0104 260 0.1600 125 12/(12+13) 0.0000
7200 00AE 174 0.2240 124 5/(5+2) 0.0064
9600 0082 130 0.1600 93 5/(5+2) 0.0064
19200 0041 65 0.1600 31 10/(10+11) 0.0064
38400 0021 33 1.3760 12 7/(7+12) 0.0594
56000 0021 22 1.4400 13 7/(7+5) 0.0160
57600 0016 22 1.3760 19 7/(7+1) 0.0594
112000 000B 11 1.4400 6 7/(7+6) 0.1600
115200 000B 11 1.3760 4 7/(7+12) 0.0594
224000 0006 6 7.5200 3 7/(7+6) 0.1600
448000 0003 3 7.5200 2 5/(5+2) 0.3520

[1] Values in the row represent decimal equivalent of a 16 bit long content (DLM:DLL).
[2] Values in the row represent hex equivalent of a 16 bit long content (DLM:DLL).
[3] Refers to the percent error between desired and actual baudrate.

9.3.6 UART0 Interrupt Enable Register (U0IER - 0xE000 C004, when

DLAB = 0)
The U0IER is used to enable UART0 interrupt sources.

Table 103: UART0 Interrupt Enable Register (U0IER - address 0xE000 C004, when DLAB = 0)
bit description
Bit Symbol Value Description Reset
value
0 RBR Interrupt U0IER[0] enables the Receive Data Available interrupt 0
Enable for UART0. It also controls the Character Receive
Time-out interrupt.
0 Disable the RDA interrupts.
1 Enable the RDA interrupts.
1 THRE U0IER[1] enables the THRE interrupt for UART0. The 0
Interrupt status of this can be read from U0LSR[5].
Enable 0 Disable the THRE interrupts.
1 Enable the THRE interrupts.
2 RX Line U0IER[2] enables the UART0 RX line status interrupts. 0
Status The status of this interrupt can be read from U0LSR[4:1].
Interrupt 0 Disable the RX line status interrupts.
Enable
1 Enable the RX line status interrupts.

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Table 103: UART0 Interrupt Enable Register (U0IER - address 0xE000 C004, when DLAB = 0)
bit description
Bit Symbol Value Description Reset
value
7:4 - - Reserved, user software should not write ones to NA
reserved bits. The value read from a reserved bit is not
defined.
8 ABEOIntEn[1] U1IER9 enables the end of auto-baud interrupt. 0
0 Disable End of Auto-baud Interrupt.
1 Enable End of Auto-baud Interrupt.
9 ABTOIntEn[1] U1IER8 enables the auto-baud time-out interrupt. 0
0 Disable Auto-baud Time-out Interrupt.
1 Enable Auto-baud Time-out Interrupt.
31:10 - - Reserved, user software should not write ones to NA
reserved bits. The value read from a reserved bit is not
defined.

[1] This feature is available in LPC213x/01 devices only.

9.3.7 UART0 Interrupt Identification Register (U0IIR - 0xE000 C008, Read

Only)
The U0IIR provides a status code that denotes the priority and source of a pending
interrupt. The interrupts are frozen during an U0IIR access. If an interrupt occurs during
an U0IIR access, the interrupt is recorded for the next U0IIR access.

Table 104: UART0 Interrupt Identification Register (UOIIR - address 0xE000 C008, read only)
bit description
Bit Symbol Value Description Reset
value
0 Interrupt Note that U0IIR[0] is active low. The pending interrupt can 1
Pending be determined by evaluating U0IIR[3:1].
0 At least one interrupt is pending.
1 No pending interrupts.
3:1 Interrupt U0IER[3:1] identifies an interrupt corresponding to the 0
Identification UART0 Rx FIFO. All other combinations of U0IER[3:1] not
listed above are reserved (000,100,101,111).
011 1 - Receive Line Status (RLS).
010 2a - Receive Data Available (RDA).
110 2b - Character Time-out Indicator (CTI).
001 3 - THRE Interrupt
5:4 - Reserved, user software should not write ones to reserved NA
bits. The value read from a reserved bit is not defined.
7:6 FIFO Enable These bits are equivalent to U0FCR[0]. 0
8 ABEOInt[1] End of auto-baud interrupt. True if auto-baud has finished 0
successfully and interrupt is enabled.
9 ABTOInt[1] Auto-baud time-out interrupt. True if auto-baud has timed 0
out and interrupt is enabled.
31:10 - Reserved, user software should not write ones to reserved NA
bits. The value read from a reserved bit is not defined.
UM10120 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved.

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[1] This feature is available in LPC213x/01 devices only.

Interrupts are handled as described in Table 105. Given the status of U0IIR[3:0], an
interrupt handler routine can determine the cause of the interrupt and how to clear the
active interrupt. The U0IIR must be read in order to clear the interrupt prior to exiting the
Interrupt Service Routine.

The UART0 RLS interrupt (U0IIR[3:1] = 011) is the highest priority interrupt and is set
whenever any one of four error conditions occur on the UART0 Rx input: overrun error
(OE), parity error (PE), framing error (FE) and break interrupt (BI). The UART0 Rx error
condition that set the interrupt can be observed via U0LSR[4:1]. The interrupt is cleared
upon an U0LSR read.

The UART0 RDA interrupt (U0IIR[3:1] = 010) shares the second level priority with the CTI
interrupt (U0IIR[3:1] = 110). The RDA is activated when the UART0 Rx FIFO reaches the
trigger level defined in U0FCR[7:6] and is reset when the UART0 Rx FIFO depth falls
below the trigger level. When the RDA interrupt goes active, the CPU can read a block of
data defined by the trigger level.

The CTI interrupt (U0IIR[3:1] = 110) is a second level interrupt and is set when the UART0
Rx FIFO contains at least one character and no UART0 Rx FIFO activity has occurred in
3.5 to 4.5 character times. Any UART0 Rx FIFO activity (read or write of UART0 RSR) will
clear the interrupt. This interrupt is intended to flush the UART0 RBR after a message has
been received that is not a multiple of the trigger level size. For example, if a peripheral
wished to send a 105 character message and the trigger level was 10 characters, the
CPU would receive 10 RDA interrupts resulting in the transfer of 100 characters and 1 to 5
CTI interrupts (depending on the service routine) resulting in the transfer of the remaining
5 characters.

Table 105: UART0 interrupt handling

U0IIR[3:0] Priority Interrupt Type Interrupt Source Interrupt Reset
value[1]
0001 - None None -
0110 Highest RX Line Status / Error OE[2] or PE[2] or FE[2] or BI[2] U0LSR Read[2]
0100 Second RX Data Available Rx data available or trigger level reached in FIFO U0RBR Read[3] or
(U0FCR0=1) UART0 FIFO drops
below trigger level
1100 Second Character Time-out Minimum of one character in the Rx FIFO and no U0RBR Read[3]
indication character input or removed during a time period
depending on how many characters are in FIFO
and what the trigger level is set at (3.5 to 4.5
character times).
The exact time will be:
[(word length) × 7 − 2] × 8 + [(trigger level −
number of characters) × 8 + 1] RCLKs
0010 Third THRE THRE[2] U0IIR Read (if source
of interrupt) or THR
write[4]

[1] Values "0000", “0011”, “0101”, “0111”, “1000”, “1001”, “1010”, “1011”,”1101”,”1110”,”1111” are reserved.
[2] For details see Section 9.3.10 “UART0 Line Status Register (U0LSR - 0xE000 C014, Read Only)”
[3] For details see Section 9.3.1 “UART0 Receiver Buffer Register (U0RBR - 0xE000 C000, when DLAB = 0, Read Only)”

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[4] For details see Section 9.3.7 “UART0 Interrupt Identification Register (U0IIR - 0xE000 C008, Read Only)” and Section 9.3.2 “UART0
Transmit Holding Register (U0THR - 0xE000 C000, when DLAB = 0, Write Only)”

The UART0 THRE interrupt (U0IIR[3:1] = 001) is a third level interrupt and is activated
when the UART0 THR FIFO is empty provided certain initialization conditions have been
met. These initialization conditions are intended to give the UART0 THR FIFO a chance to
fill up with data to eliminate many THRE interrupts from occurring at system start-up. The
initialization conditions implement a one character delay minus the stop bit whenever
THRE=1 and there have not been at least two characters in the U0THR at one time since
the last THRE = 1 event. This delay is provided to give the CPU time to write data to
U0THR without a THRE interrupt to decode and service. A THRE interrupt is set
immediately if the UART0 THR FIFO has held two or more characters at one time and
currently, the U0THR is empty. The THRE interrupt is reset when a U0THR write occurs or
a read of the U0IIR occurs and the THRE is the highest interrupt (U0IIR[3:1] = 001).

9.3.8 UART0 FIFO Control Register (U0FCR - 0xE000 C008)

The U0FCR controls the operation of the UART0 Rx and TX FIFOs.

Table 106: UART0 FIFO Control Register (U0FCR - address 0xE000 C008) bit description
Bit Symbol Value Description Reset value
0 FIFO Enable 0 UART0 FIFOs are disabled. Must not be used in the 0
application.
1 Active high enable for both UART0 Rx and TX
FIFOs and U0FCR[7:1] access. This bit must be set
for proper UART0 operation. Any transition on this
bit will automatically clear the UART0 FIFOs.
1 RX FIFO 0 No impact on either of UART0 FIFOs. 0
Reset 1 Writing a logic 1 to U0FCR[1] will clear all bytes in
UART0 Rx FIFO and reset the pointer logic. This bit
is self-clearing.
2 TX FIFO 0 No impact on either of UART0 FIFOs. 0
Reset 1 Writing a logic 1 to U0FCR[2] will clear all bytes in
UART0 TX FIFO and reset the pointer logic. This bit
is self-clearing.
5:3 - 0 Reserved, user software should not write ones to NA
reserved bits. The value read from a reserved bit is
not defined.
7:6 RX Trigger These two bits determine how many receiver 0
Level UART0 FIFO characters must be written before an
00 interrupt is activated.
Trigger level 0 (1 character or 0x01)
01 Trigger level 1 (4 characters or 0x04)
10 Trigger level 2 (8 characters or 0x08)
11 Trigger level 3 (14 characters or 0x0E)

9.3.9 UART0 Line Control Register (U0LCR - 0xE000 C00C)

The U0LCR determines the format of the data character that is to be transmitted or
received.

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Table 107: UART0 Line Control Register (U0LCR - address 0xE000 C00C) bit description
Bit Symbol Value Description Reset value
1:0 Word Length 00 5 bit character length 0
Select 01 6 bit character length
10 7 bit character length
11 8 bit character length
2 Stop Bit Select 0 1 stop bit. 0
1 2 stop bits (1.5 if U0LCR[1:0]=00).
3 Parity Enable 0 Disable parity generation and checking. 0
1 Enable parity generation and checking.
5:4 Parity Select 00 Odd parity. Number of 1s in the transmitted character and the 0
attached parity bit will be odd.
01 Even Parity. Number of 1s in the transmitted character and the
attached parity bit will be even.
10 Forced "1" stick parity.
11 Forced "0" stick parity.
6 Break Control 0 Disable break transmission. 0
1 Enable break transmission. Output pin UART0 TXD is forced
to logic 0 when U0LCR[6] is active high.
7 Divisor Latch 0 Disable access to Divisor Latches. 0
Access Bit (DLAB) 1 Enable access to Divisor Latches.

9.3.10 UART0 Line Status Register (U0LSR - 0xE000 C014, Read Only)
The U0LSR is a read-only register that provides status information on the UART0 TX and
RX blocks.

Table 108: UART0 Line Status Register (U0LSR - address 0xE000 C014, read only) bit description
Bit Symbol Value Description Reset value
0 Receiver Data U0LSR0 is set when the U0RBR holds an unread character and is cleared 0
Ready when the UART0 RBR FIFO is empty.
(RDR) 0 U0RBR is empty.
1 U0RBR contains valid data.
1 Overrun Error The overrun error condition is set as soon as it occurs. An U0LSR read clears 0
(OE) U0LSR1. U0LSR1 is set when UART0 RSR has a new character assembled
and the UART0 RBR FIFO is full. In this case, the UART0 RBR FIFO will not
be overwritten and the character in the UART0 RSR will be lost.
0 Overrun error status is inactive.
1 Overrun error status is active.
2 Parity Error When the parity bit of a received character is in the wrong state, a parity error 0
(PE) occurs. An U0LSR read clears U0LSR[2]. Time of parity error detection is
dependent on U0FCR[0].
Note: A parity error is associated with the character at the top of the UART0
RBR FIFO.
0 Parity error status is inactive.
1 Parity error status is active.

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Table 108: UART0 Line Status Register (U0LSR - address 0xE000 C014, read only) bit description
Bit Symbol Value Description Reset value
3 Framing Error When the stop bit of a received character is a logic 0, a framing error occurs. 0
(FE) An U0LSR read clears U0LSR[3]. The time of the framing error detection is
dependent on U0FCR0. Upon detection of a framing error, the Rx will attempt
to resynchronize to the data and assume that the bad stop bit is actually an
early start bit. However, it cannot be assumed that the next received byte will
be correct even if there is no Framing Error.
Note: A framing error is associated with the character at the top of the UART0
RBR FIFO.
0 Framing error status is inactive.
1 Framing error status is active.
4 Break Interrupt When RXD0 is held in the spacing state (all 0’s) for one full character 0
(BI) transmission (start, data, parity, stop), a break interrupt occurs. Once the
break condition has been detected, the receiver goes idle until RXD0 goes to
marking state (all 1’s). An U0LSR read clears this status bit. The time of break
detection is dependent on U0FCR[0].
Note: The break interrupt is associated with the character at the top of the
UART0 RBR FIFO.
0 Break interrupt status is inactive.
1 Break interrupt status is active.
5 Transmitter THRE is set immediately upon detection of an empty UART0 THR and is 1
Holding cleared on a U0THR write.
Register Empty 0 U0THR contains valid data.
(THRE))
1 U0THR is empty.
6 Transmitter TEMT is set when both U0THR and U0TSR are empty; TEMT is cleared when 1
Empty either the U0TSR or the U0THR contain valid data.
(TEMT) 0 U0THR and/or the U0TSR contains valid data.
1 U0THR and the U0TSR are empty.
7 Error in RX U0LSR[7] is set when a character with a Rx error such as framing error, parity 0
FIFO error or break interrupt, is loaded into the U0RBR. This bit is cleared when the
(RXFE) U0LSR register is read and there are no subsequent errors in the UART0
FIFO.
0 U0RBR contains no UART0 RX errors or U0FCR[0]=0.
1 UART0 RBR contains at least one UART0 RX error.

9.3.11 UART0 Scratch pad register (U0SCR - 0xE000 C01C)

The U0SCR has no effect on the UART0 operation. This register can be written and/or
read at user’s discretion. There is no provision in the interrupt interface that would indicate
to the host that a read or write of the U0SCR has occurred.

Table 109: UART0 Scratch pad register (U0SCR - address 0xE000 C01C) bit description
Bit Symbol Description Reset value
7:0 Pad A readable, writable byte. 0x00

9.3.12 UART0 Auto-baud Control Register (U0ACR - 0xE000 C020)

This feature is available in LPC213x/01 devices only.

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The UART0 Auto-baud Control Register (U0ACR) controls the process of measuring the
incoming clock/data rate for the baud rate generation and can be read and written at
user’s discretion.

Table 110: Auto-baud Control Register (U0ACR - 0xE000 C020) bit description
Bit Symbol Value Description Reset value
0 Start This bit is automatically cleared after auto-baud 0
completion.
0 Auto-baud stop (auto-baud is not running).
1 Auto-baud start (auto-baud is running).Auto-baud run
bit. This bit is automatically cleared after auto-baud
completion.
1 Mode Auto-baud mode select bit. 0
0 Mode 0.
1 Mode 1.
2 AutoRestart 0 No restart 0
1 Restart in case of time-out (counter restarts at next
UART0 Rx falling edge)
7:3 - NA Reserved, user software should not write ones to 0
reserved bits. The value read from a reserved bit is not
defined.
8 ABEOIntClr End of auto-baud interrupt clear bit (write only 0
accessible). Writing a 1 will clear the corresponding
interrupt in the U0IIR. Writing a 0 has no impact.
9 ABTOIntClr Auto-baud time-out interrupt clear bit (write only 0
accessible). Writing a 1 will clear the corresponding
interrupt in the U0IIR. Writing a 0 has no impact.
31:10 - NA Reserved, user software should not write ones to 0
reserved bits. The value read from a reserved bit is not
defined.

9.3.13 Auto-baud
This feature is available in LPC213x/01 devices only.

The UART0 auto-baud function can be used to measure the incoming baud-rate based on
the ”AT" protocol (Hayes command). If enabled the auto-baud feature will measure the bit
time of the receive data stream and set the divisor latch registers U0DLM and U0DLL
accordingly.

Auto-baud is started by setting the U0ACR Start bit. Auto-baud can be stopped by clearing
the U0ACR Start bit. The Start bit will clear once auto-baud has finished and reading the
bit will return the status of auto-baud (pending/finished).

Two auto-baud measuring modes are available which can be selected by the U0ACR
Mode bit. In mode 0 the baud-rate is measured on two subsequent falling edges of the
UART0 Rx pin (the falling edge of the start bit and the falling edge of the least significant
bit). In mode 1 the baud-rate is measured between the falling edge and the subsequent
rising edge of the UART0 Rx pin (the length of the start bit).

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The U0ACR AutoRestart bit can be used to automatically restart baud-rate measurement
if a time-out occurs (the rate measurement counter overflows). If this bit is set the rate
measurement will restart at the next falling edge of the UART0 Rx pin.

The auto-baud function can generate two interrupts.

• The U0IIR ABTOInt interrupt will get set if the interrupt is enabled (U0IER ABToIntEn
is set and the auto-baud rate measurement counter overflows).
• The U0IIR ABEOInt interrupt will get set if the interrupt is enabled (U0IER ABEOIntEn
is set and the auto-baud has completed successfully).

The auto-baud interrupts have to be cleared by setting the corresponding U0ACR

ABTOIntClr and ABEOIntEn bits.

Typically the fractional baud-rate generator is disabled (DIVADDVAL = 0) during

auto-baud. However, if the fractional baud-rate generator is enabled (DIVADDVAL > 0), it
is going to impact the measuring of UART0 Rx pin baud-rate, but the value of the U0FDR
register is not going to be modified after rate measurement. Also, when auto-baud is used,
any write to U0DLM and U0DLL registers should be done before U0ACR register write.
The minimum and the maximum baudrates supported by UART0 are function of PCLK,
number of data bits, stop-bits and parity bits.

(3)

2 × P CLK PCLK
ratemin = ------------------------- ≤ UART0 baudrate ≤ ------------------------------------------------------------------------------------------------------------ = ratemax
16 × 2 15 16 × ( 2 + databits + paritybits + stopbits )

9.3.13.1 Auto-baud Modes

When the software is expecting an ”AT" command, it configures the UART0 with the
expected character format and sets the U0ACR Start bit. The initial values in the divisor
latches U0DLM and U0DLM don‘t care. Because of the ”A" or ”a" ASCII coding
(”A" = 0x41, ”a" = 0x61), the UART0 Rx pin sensed start bit and the LSB of the expected
character are delimited by two falling edges. When the U0ACR Start bit is set, the
auto-baud protocol will execute the following phases:

1. On U0ACR Start bit setting, the baud-rate measurement counter is reset and the
UART0 U0RSR is reset. The U0RSR baud rate is switch to the highest rate.
2. A falling edge on UART0 Rx pin triggers the beginning of the start bit. The rate
measuring counter will start counting PCLK cycles optionally pre-scaled by the
fractional baud-rate generator.
3. During the receipt of the start bit, 16 pulses are generated on the RSR baud input with
the frequency of the (fractional baud-rate pre-scaled) UART0 input clock,
guaranteeing the start bit is stored in the U0RSR.
4. During the receipt of the start bit (and the character LSB for mode = 0) the rate
counter will continue incrementing with the pre-scaled UART0 input clock (PCLK).
5. If Mode = 0 then the rate counter will stop on next falling edge of the UART0 Rx pin. If
Mode = 1 then the rate counter will stop on the next rising edge of the UART0 Rx pin.

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6. The rate counter is loaded into U0DLM/U0DLL and the baud-rate will be switched to
normal operation. After setting the U0DLM/U0DLL the end of auto-baud interrupt
U0IIR ABEOInt will be set, if enabled. The U0RSR will now continue receiving the
remaining bits of the ”A/a" character.

'A' (0x41) or 'a' (0x61)

start bit0 bit1 bit2 bit3 bit4 bit5 bit6 bit7 parity stop

UART0 RX
start bit LSB of 'A' or 'a'

U0ACR start

rate counter

16xbaud_rate
16 cycles 16 cycles

a. Mode 0 (start bit and LSB are used for auto-baud)

'A' (0x41) or 'a' (0x61)

start bit0 bit1 bit2 bit3 bit4 bit5 bit6 bit7 parity stop

UART0 RX
start bit LSB of 'A' or 'a'

U0ACR start

rate counter

16xbaud_rate
16 cycles

b. Mode 1 (only start bit is used for auto-baud)

Fig 18. Autobaud a) mode 0 and b) mode 1 waveform.

9.3.14 UART0 Transmit Enable Register (U0TER - 0xE000 C030)

LPC213x’s U0TER enables implementation of software flow control. When TXEn=1,
UART0 transmitter will keep sending data as long as they are available. As soon as TXEn
becomes 0, UART0 transmission will stop.

Table 111 describes how to use TXEn bit in order to achieve software flow control.

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Table 111: UART0 Transmit Enable Register (U0TER - address 0xE000 C030) bit description
Bit Symbol Description Reset
value
6:0 - Reserved, user software should not write ones to reserved bits. The NA
value read from a reserved bit is not defined.
7 TXEN When this bit is 1, as it is after a Reset, data written to the THR is output 1
on the TXD pin as soon as any preceding data has been sent. If this bit
is cleared to 0 while a character is being sent, the transmission of that
character is completed, but no further characters are sent until this bit is
set again. In other words, a 0 in this bit blocks the transfer of characters
from the THR or TX FIFO into the transmit shift register. Software
implementing software-handshaking can clear this bit when it receives
an XOFF character (DC3). Software can set this bit again when it
receives an XON (DC1) character.

9.4 Architecture
The architecture of the UART0 is shown below in the block diagram.

The APB interface provides a communications link between the CPU or host and the
UART0.

The UART0 receiver block, U0RX, monitors the serial input line, RXD0, for valid input.
The UART0 RX Shift Register (U0RSR) accepts valid characters via RXD0. After a valid
character is assembled in the U0RSR, it is passed to the UART0 RX Buffer Register FIFO
to await access by the CPU or host via the generic host interface.

The UART0 transmitter block, U0TX, accepts data written by the CPU or host and buffers
the data in the UART0 TX Holding Register FIFO (U0THR). The UART0 TX Shift Register
(U0TSR) reads the data stored in the U0THR and assembles the data to transmit via the
serial output pin, TXD0.

The UART0 Baud Rate Generator block, U0BRG, generates the timing enables used by
the UART0 TX block. The U0BRG clock input source is the APB clock (PCLK). The main
clock is divided down per the divisor specified in the U0DLL and U0DLM registers. This
divided down clock is a 16x oversample clock, NBAUDOUT.

The interrupt interface contains registers U0IER and U0IIR. The interrupt interface
receives several one clock wide enables from the U0TX and U0RX blocks.

Status information from the U0TX and U0RX is stored in the U0LSR. Control information
for the U0TX and U0RX is stored in the U0LCR.

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U0TX
NTXRDY

TXD0
U0THR U0TSR

U0BRG

U0DLL NBAUDOUT

U0DLM RCLK

U0RX
NRXRDY
INTERRUPT
RXD0
U0RBR U0RSR

U0INTR U0IER

U0IIR
U0FCR

U0LSR
U0SCR

U0LCR

PA[2:0]

PSEL

PSTB

PWRITE

APB
PD[7:0] DDIS
INTERFACE

PCLK

Fig 19. UART0 block diagram

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Chapter 10: LPC213x UART1
Rev. 3 — 4 October 2010 User manual

10.1 Features
• UART1 is identical to UART0, with the addition of a modem interface and flow control.
• 16 byte Receive and Transmit FIFOs.
• Register locations conform to ‘550 industry standard.
• Receiver FIFO trigger points at 1, 4, 8, and 14 bytes.
• Mechanism that enables software and hardware flow control implementation.

10.1.1 Enhancements introduced with LPC213x/01 devices

Powerful Fractional baud rate generator with autobauding provides standard baud rates
such as 115200 with any crystal frequency above 2 MHz. Flow-control handshake
(auto-CTS/RTS) is fully implemented in hardware.

10.2 Pin description

Table 112: UART1 pin description
Pin Type Description
RXD1 Input Serial Input. Serial receive data.
TXD1 Output Serial Output. Serial transmit data.
CTS1[1] Input Clear To Send. Active low signal indicates if the external modem is ready to accept transmitted data via
TXD1 from the UART1. In normal operation of the modem interface (U1MCR[4] = 0), the complement
value of this signal is stored in U1MSR[4]. State change information is stored in U1MSR[0] and is a
source for a priority level 4 interrupt, if enabled (U1IER[3] = 1).
DCD1[1] Input Data Carrier Detect. Active low signal indicates if the external modem has established a communication
link with the UART1 and data may be exchanged. In normal operation of the modem interface
(U1MCR[4]=0), the complement value of this signal is stored in U1MSR[7]. State change information is
stored in U1MSR3 and is a source for a priority level 4 interrupt, if enabled (U1IER[3] = 1).
DSR1[1] Input Data Set Ready. Active low signal indicates if the external modem is ready to establish a communications
link with the UART1. In normal operation of the modem interface (U1MCR[4] = 0), the complement value
of this signal is stored in U1MSR[5]. State change information is stored in U1MSR[1] and is a source for a
priority level 4 interrupt, if enabled (U1IER[3] = 1).
DTR1[1] Output Data Terminal Ready. Active low signal indicates that the UART1 is ready to establish connection with
external modem. The complement value of this signal is stored in U1MCR[0].
RI1[1] Input Ring Indicator. Active low signal indicates that a telephone ringing signal has been detected by the
modem. In normal operation of the modem interface (U1MCR[4] = 0), the complement value of this signal
is stored in U1MSR[6]. State change information is stored in U1MSR[2] and is a source for a priority level
4 interrupt, if enabled (U1IER[3] = 1).
RTS1[1] Output Request To Send. Active low signal indicates that the UART1 would like to transmit data to the external
modem. The complement value of this signal is stored in U1MCR[1].

[1] Not available in LPC2131, LPC2132, LPC2131/01, and LPC2132/01.

10.3 Register description

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Table 113: UART1 register map
Name Description Bit functions and addresses Access Reset Address
MSB LSB value

BIT7 BIT6 BIT5 BIT4 BIT3 BIT2 BIT1 BIT0

U1RBR Receiver Buffer 8-bit Read Data RO NA 0xE001 0000
Register (DLAB=0)
U1THR Transmit Holding 8-bit Write Data WO NA 0xE001 0000
Register (DLAB=0)
U1DLL Divisor Latch LSB 8-bit Data R/W 0x01 0xE001 0000
(DLAB=1)
U1DLM Divisor Latch MSB 8-bit Data R/W 0x00 0xE001 0004
(DLAB=1)
U1IER Interrupt Enable - - - - - - EABTO[2] EABEO[2] R/W 0x00 0xE001 0004
All information provided in this document is subject to legal disclaimers.

Register En.CTS - - - E.Modem En. RX Enable En. RX (DLAB=0)

Int[1] Stat.Int[1] Lin.St. Int THRE Int Dat.Av.Int
Rev. 3 — 4 October 2010

U1IIR Interrupt ID Reg. - - - - - - ABTOI[2] ABEOI[2] RO 0x01 0xE001 0008

FIFOs Enabled - - IIR3 IIR2 IIR1 IIR0
U1FCR FIFO Control RX Trigger - - - TX FIFO RX FIFO FIFO WO 0x00 0xE001 0008
Register Reset Reset Enable
U1LCR Line Control DLAB Set Stick Even Parity No. of Word Length Select R/W 0x00 0xE001 000C
Register Break Parity Par.Selct. Enable Stop Bits
U1MCR[1] Modem Ctrl. Reg. CTSen[2] RTSen[2] - LoopBck. - - RTS DTR R/W 0x00 0xE001 0010
U1LSR Line Status RX FIFO TEMT THRE BI FE PE OE DR RO 0x60 0xE001 0014
Register Error
U1MSR[1] Modem Status DCD RI DSR CTS Delta Trailing Delta Delta RO 0x00 0xE001 0018
Register DCD Edge RI DSR CTS
U1SCR Scratch Pad Reg. 8-bit Data R/W 0x00 0xE001 001C

Chapter 10: LPC213x UART1

U1ACR[2] Auto-baud Control - - - - - - ABTO ABEO R/W 0x00 0xE001 0020
Register IntClr IntClr
- - - - - Aut.Rstrt. Mode Start

UM10120
U1FDR[2] Fractional Divider Reserved[31:8] R/W 0x10 0xE001 0028
© NXP B.V. 2010. All rights reserved.

Register MulVal DivAddVal

U1TER TX. Enable Reg. TXEN - - - - - - - R/W 0x80 0xE001 0030
110 of 297

[1] Modem specific features are available in LPC213x only.

[2] Available in LPC213x/01 devices only.
NXP Semiconductors UM10120
Chapter 10: LPC213x UART1

10.3.1 UART1 Receiver Buffer Register (U1RBR - 0xE001 0000, when

DLAB = 0 Read Only)
The U1RBR is the top byte of the UART1 RX FIFO. The top byte of the RX FIFO contains
the oldest character received and can be read via the bus interface. The LSB (bit 0)
represents the “oldest” received data bit. If the character received is less than 8 bits, the
unused MSBs are padded with zeroes.

The Divisor Latch Access Bit (DLAB) in U1LCR must be zero in order to access the
U1RBR. The U1RBR is always Read Only.

Since PE, FE and BI bits correspond to the byte sitting on the top of the RBR FIFO (i.e.
the one that will be read in the next read from the RBR), the right approach for fetching the
valid pair of received byte and its status bits is first to read the content of the U1LSR
register, and then to read a byte from the U1RBR.

Table 114: UART1 Receiver Buffer Register (U1RBR - address 0xE001 0000, when DLAB = 0
Read Only) bit description
Bit Symbol Description Reset value
7:0 RBR The UART1 Receiver Buffer Register contains the oldest undefined
received byte in the UART1 RX FIFO.

10.3.2 UART1 Transmitter Holding Register (U1THR - 0xE001 0000, when

DLAB = 0 Write Only)
The U1THR is the top byte of the UART1 TX FIFO. The top byte is the newest character in
the TX FIFO and can be written via the bus interface. The LSB represents the first bit to
transmit.

The Divisor Latch Access Bit (DLAB) in U1LCR must be zero in order to access the
U1THR. The U1THR is always Write Only.

Table 115: UART1 Transmitter Holding Register (U1THR - address 0xE001 0000, when
DLAB = 0 Write Only) bit description
Bit Symbol Description Reset value
7:0 THR Writing to the UART1 Transmit Holding Register causes the data NA
to be stored in the UART1 transmit FIFO. The byte will be sent
when it reaches the bottom of the FIFO and the transmitter is
available.

10.3.3 UART1 Divisor Latch Registers 0 and 1 (U1DLL - 0xE001 0000 and
U1DLM - 0xE001 0004, when DLAB = 1)
The UART1 Divisor Latch is part of the UART1 Fractional Baud Rate Generator and holds
the value used to divide the clock supplied by the fractional prescaler in order to produce
the baud rate clock, which must be 16x the desired baud rate (Equation 4). The U1DLL
and U1DLM registers together form a 16 bit divisor where U1DLL contains the lower 8 bits
of the divisor and U1DLM contains the higher 8 bits of the divisor. A 0x0000 value is
treated like a 0x0001 value as division by zero is not allowed.The Divisor Latch Access Bit
(DLAB) in U1LCR must be one in order to access the UART1 Divisor Latches.

Details on how to select the right value for U1DLL and U1DLM can be found later on in
this chapter.

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Table 116: UART1 Divisor Latch LSB register (U1DLL - address 0xE001 0000, when
DLAB = 1) bit description
Bit Symbol Description Reset value
7:0 DLLSB The UART1 Divisor Latch LSB Register, along with the U1DLM 0x01
register, determines the baud rate of the UART1.

Table 117: UART1 Divisor Latch MSB register (U1DLM - address 0xE001 0004, when
DLAB = 1) bit description
Bit Symbol Description Reset value
7:0 DLMSB The UART1 Divisor Latch MSB Register, along with the U1DLL 0x00
register, determines the baud rate of the UART1.

10.3.4 UART1 Fractional Divider Register (U1FDR - 0xE001 0028)

This register is available in LPC213x/01 devices only.

The UART1 Fractional Divider Register (U1FDR) controls the clock pre-scaler for the
baud rate generation and can be read and written at user’s discretion. This pre-scaler
takes the APB clock and generates an output clock per specified fractional requirements.

Important: If the fractional divider is active (DIVADDVAL > 0) and DLM = 0, the value of
the DLL register must be 3 or greater.

Table 118: UART1 Fractional Divider Register (U1FDR - address 0xE001 0028) bit description
Bit Function Description Reset value
3:0 DIVADDVAL Baudrate generation pre-scaler divisor value. If this field is 0, 0
fractional baudrate generator will not impact the UART1
baudrate.
7:4 MULVAL Baudrate pre-scaler multiplier value. This field must be greater 1
or equal 1 for UART1 to operate properly, regardless of
whether the fractional baudrate generator is used or not.
31:8 - Reserved, user software should not write ones to reserved bits. NA
The value read from a reserved bit is not defined.

This register controls the clock pre-scaler for the baud rate generation. The reset value of
the register keeps the fractional capabilities of UART1 disabled making sure that UART1
is fully software and hardware compatible with UARTs not equipped with this feature.

UART1 baudrate can be calculated as:

(4)

PCLK
UART1 baudrate = ----------------------------------------------------------------------------------------------------------------------------------
16 × ( 256 × U1DLM + U1DLL ) × ⎛⎝ 1 + -----------------------------⎞⎠
DivAddVal
MulVal

Where PCLK is the peripheral clock, U1DLM and U1DLL are the standard UART1 baud
rate divider registers, and DIVADDVAL and MULVAL are UART1 fractional baudrate
generator specific parameters.

The value of MULVAL and DIVADDVAL should comply to the following conditions:

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1. 0 < MULVAL ≤ 15
2. 0 ≤ DIVADDVAL ≤ 15

If the U1FDR register value does not comply to these two requests then the fractional
divider output is undefined. If DIVADDVAL is zero then the fractional divider is disabled
and the clock will not be divided.

The value of the U1FDR should not be modified while transmitting/receiving data or data
may be lost or corrupted.

Usage Note: For practical purposes, UART1 baudrate formula can be written in a way
that identifies the part of a UART baudrate generated without the fractional baudrate
generator, and the correction factor that this module adds:

(5)

PCLK MulVal
UART1 baudrate = -------------------------------------------------------------------------------- × ------------------------------------------------------------
16 × ( 256 × U1DLM + U1DLL ) ( MulVal + DivAddVal )

Based on this representation, fractional baudrate generator contribution can also be

described as a prescaling with a factor of MULVAL / (MULVAL + DIVADDVAL).

10.3.5 UART1 baudrate calculation

Example 1: Using UART1baudrate formula from above, it can be determined that system
with PCLK = 20 MHz, U1DL = 130 (U1DLM = 0x00 and U1DLL = 0x82), DIVADDVAL = 0
and MULVAL = 1 will enable UART1 with UART1baudrate = 9615 bauds.

Example 2: Using UART1baudrate formula from above, it can be determined that system
with PCLK = 20 MHz, U1DL = 93 (U1DLM = 0x00 and U1DLL = 0x5D), DIVADDVAL = 2
and MULVAL = 5 will enable UART1 with UART1baudrate = 9600 bauds.

Table 119: Baudrates available when using 20 MHz peripheral clock (PCLK = 20 MHz)
Desired MULVAL = 0 DIVADDVAL = 0 Optimal MULVAL & DIVADDVAL
baudrate U1DLM:U1DLL % error[3] U1DLM:U1DLL Fractional % error[3]
hex[2] dec[1] dec[1] pre-scaler value
MULDIV
MULDIV + DIVADDVAL

50 61A8 25000 0.0000 25000 1/(1+0) 0.0000

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2400 0209 521 0.0320 250 12/(12+13) 0.0000

10.3.6 UART1 Interrupt Enable Register (U1IER - 0xE001 0004, when

DLAB = 0)
The U1IER is used to enable UART1 interrupt sources.

Table 120: UART1 Interrupt Enable Register (U1IER - address 0xE001 0004, when DLAB = 0)
bit description
Bit Symbol Value Description Reset value
0 RBR Interrupt U1IER[0] enables the Receive Data Available 0
Enable interrupt for UART1. It also controls the Character
Receive Time-out interrupt.
0 Disable the RDA interrupts.
1 Enable the RDA interrupts.
1 THRE U1IER[1] enables the THRE interrupt for UART1. 0
Interrupt The status of this interrupt can be read from
Enable U1LSR[5].
0 Disable the THRE interrupts.
1 Enable the THRE interrupts.
2 RX Line U1IER[2] enables the UART1 RX line status 0
Interrupt interrupts. The status of this interrupt can be read
Enable from U1LSR[4:1].
0 Disable the RX line status interrupts.
1 Enable the RX line status interrupts.

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Table 120: UART1 Interrupt Enable Register (U1IER - address 0xE001 0004, when DLAB = 0)
bit description
Bit Symbol Value Description Reset value
3 Modem U1IER[3] enables the modem interrupt. The status 0
Status of this interrupt can be read from U1MSR[3:0].
Interrupt 0 Disable the modem interrupt.
Enable[1]
1 Enable the modem interrupt.
6:4 - - Reserved, user software should not write ones to NA
reserved bits. The value read from a reserved bit is
not defined.
7 CTS Interrupt If auto-CTS mode is enabled this bit 0
Enable[1] enables/disables the modem status interrupt
generation on a CTS1 signal transition. If auto-CTS
mode is disabled a CTS1 transition will generate an
interrupt if Modem Status Interrupt Enable
(U1IER[3]) is set.
In normal operation a CTS1 signal transition will
generate a Modem Status Interrupt unless the
interrupt has been disabled by clearing the U1IER[3]
bit in the U1IER register. In auto-CTS mode a
transition on the CTS1 bit will trigger an interrupt
only if both the U1IER[3] and U1IER[7] bits are set.
0 Disable the CTS interrupt.
1 Enable the CTS interrupt.
8 ABEOIntEn[2] U1IER9 enables the end of auto-baud interrupt. 0
0 Disable End of Auto-baud Interrupt.
1 Enable End of Auto-baud Interrupt.
9 ABTOIntEn[2] U1IER8 enables the auto-baud time-out interrupt. 0
0 Disable Auto-baud Time-out Interrupt.
1 Enable Auto-baud Time-out Interrupt.
31:10 - - Reserved, user software should not write ones to NA
reserved bits. The value read from a reserved bit is
not defined.

[1] Available in LPC2134, LPC2136, LPC2138, LPC2134/01, LPC2136/01, and LPC2138/01 only.
[2] Available in LPC2134/01, LPC2136/01, and LPC2138/01 only.

10.3.7 UART1 Interrupt Identification Register (U1IIR - 0xE001 0008, Read

Only)
The U1IIR provides a status code that denotes the priority and source of a pending
interrupt. The interrupts are frozen during an U1IIR access. If an interrupt occurs during
an U1IIR access, the interrupt is recorded for the next U1IIR access.

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Table 121: UART1 Interrupt Identification Register (U1IIR - address 0xE001 0008, read only)
bit description
Bit Symbol Value Description Reset value
0 Interrupt Note that U1IIR[0] is active low. The pending 1
Pending interrupt can be determined by evaluating
U1IIR[3:1].
0 At least one interrupt is pending.
1 No interrupt is pending.
3:1 Interrupt U1IER[3:1] identifies an interrupt corresponding to 0
Identification the UART1 Rx FIFO. All other combinations of
U1IER[3:1] not listed above are reserved
(100,101,111).
011 1 - Receive Line Status (RLS).
010 2a - Receive Data Available (RDA).
110 2b - Character Time-out Indicator (CTI).
001 3 - THRE Interrupt.
000 4 - Modem Interrupt.[1]
5:4 - Reserved, user software should not write ones to NA
reserved bits. The value read from a reserved bit is
not defined.
7:6 FIFO Enable These bits are equivalent to U1FCR[0]. 0
8 ABEOInt[2] End of auto-baud interrupt. True if auto-baud has 0
finished successfully and interrupt is enabled.
9 ABTOInt[2] Auto-baud time-out interrupt. True if auto-baud has 0
timed out and interrupt is enabled.
31:10 - Reserved, user software should not write ones to NA
reserved bits. The value read from a reserved bit is
not defined.

[1] LPC2134, LPC2136, LPC2138, LPC2134/01, LPC2136/01, and LPC2138/01 only. For all other LPC213x
devices ’000’ combination is Reserved.
[2] Available in LPC2134/01, LPC2136/01, and LPC2138/01 only.

Interrupts are handled as described in Table 83. Given the status of U1IIR[3:0], an
interrupt handler routine can determine the cause of the interrupt and how to clear the
active interrupt. The U1IIR must be read in order to clear the interrupt prior to exiting the
Interrupt Service Routine.

The UART1 RLS interrupt (U1IIR[3:1] = 011) is the highest priority interrupt and is set
whenever any one of four error conditions occur on the UART1RX input: overrun error
(OE), parity error (PE), framing error (FE) and break interrupt (BI). The UART1 Rx error
condition that set the interrupt can be observed via U1LSR[4:1]. The interrupt is cleared
upon an U1LSR read.

The UART1 RDA interrupt (U1IIR[3:1] = 010) shares the second level priority with the CTI
interrupt (U1IIR[3:1] = 110). The RDA is activated when the UART1 Rx FIFO reaches the
trigger level defined in U1FCR7:6 and is reset when the UART1 Rx FIFO depth falls below
the trigger level. When the RDA interrupt goes active, the CPU can read a block of data
defined by the trigger level.

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The CTI interrupt (U1IIR[3:1] = 110) is a second level interrupt and is set when the UART1
Rx FIFO contains at least one character and no UART1 Rx FIFO activity has occurred in
3.5 to 4.5 character times. Any UART1 Rx FIFO activity (read or write of UART1 RSR) will
clear the interrupt. This interrupt is intended to flush the UART1 RBR after a message has
been received that is not a multiple of the trigger level size. For example, if a peripheral
wished to send a 105 character message and the trigger level was 10 characters, the
CPU would receive 10 RDA interrupts resulting in the transfer of 100 characters and 1 to 5
CTI interrupts (depending on the service routine) resulting in the transfer of the remaining
5 characters.

Table 122: UART1 interrupt handling

U1IIR[3:0] Priority Interrupt Type Interrupt Source Interrupt Reset
value[1]
0001 - None None -
0110 Highest RX Line Status / Error OE[3] or PE[3] or FE[3] or BI[3] U1LSR Read[3]
0100 Second RX Data Available Rx data available or trigger level reached in FIFO U1RBR Read[4] or
(U1FCR0=1) UART1 FIFO drops
below trigger level
1100 Second Character Time-out Minimum of one character in the RX FIFO and no U1RBR Read[4]
indication character input or removed during a time period
depending on how many characters are in FIFO
and what the trigger level is set at (3.5 to 4.5
character times).
The exact time will be:
[(word length) × 7 − 2] × 8 + [(trigger level −
number of characters) × 8 + 1] RCLKs
0010 Third THRE THRE[3] U1IIR Read[5] (if source
of interrupt) or THR write
0000[2] Fourth Modem Status CTS or DSR or RI or DCD MSR Read

[1] Values "0000" (see Table note 2), “0011”, “0101”, “0111”, “1000”, “1001”, “1010”, “1011”,”1101”,”1110”,”1111” are reserved.
[2] LPC2134/6/8only.
[3] For details see Section 10.3.11 “UART1 Line Status Register (U1LSR - 0xE001 0014, Read Only)”
[4] For details see Section 10.3.1 “UART1 Receiver Buffer Register (U1RBR - 0xE001 0000, when DLAB = 0 Read Only)”
[5] For details see Section 10.3.7 “UART1 Interrupt Identification Register (U1IIR - 0xE001 0008, Read Only)” and Section 10.3.2 “UART1
Transmitter Holding Register (U1THR - 0xE001 0000, when DLAB = 0 Write Only)”

The UART1 THRE interrupt (U1IIR[3:1] = 001) is a third level interrupt and is activated
when the UART1 THR FIFO is empty provided certain initialization conditions have been
met. These initialization conditions are intended to give the UART1 THR FIFO a chance to
fill up with data to eliminate many THRE interrupts from occurring at system start-up. The
initialization conditions implement a one character delay minus the stop bit whenever
THRE = 1 and there have not been at least two characters in the U1THR at one time
since the last THRE = 1 event. This delay is provided to give the CPU time to write data to
U1THR without a THRE interrupt to decode and service. A THRE interrupt is set
immediately if the UART1 THR FIFO has held two or more characters at one time and
currently, the U1THR is empty. The THRE interrupt is reset when a U1THR write occurs or
a read of the U1IIR occurs and the THRE is the highest interrupt (U1IIR[3:1] = 001).

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The modem interrupt (U1IIR[3:1] = 000) is available in LPC2134/6/8 and matching /01
only. It is the lowest priority interrupt and is activated whenever there is any state change
on modem inputs pins, DCD, DSR or CTS. In addition, a low to high transition on modem
input RI will generate a modem interrupt. The source of the modem interrupt can be
determined by examining U1MSR[3:0]. A U1MSR read will clear the modem interrupt.

10.3.8 UART1 FIFO Control Register (U1FCR - 0xE001 0008)

The U1FCR controls the operation of the UART1 RX and TX FIFOs.

Table 123: UART1 FIFO Control Register (U1FCR - address 0xE001 0008) bit description
Bit Symbol Value Description Reset value
0 FIFO Enable 0 UART1 FIFOs are disabled. Must not be used in the application. 0
1 Active high enable for both UART1 Rx and TX FIFOs and
U1FCR[7:1] access. This bit must be set for proper UART1
operation. Any transition on this bit will automatically clear the
UART1 FIFOs.
1 RX FIFO Reset 0 No impact on either of UART1 FIFOs. 0
1 Writing a logic 1 to U1FCR[1] will clear all bytes in UART1 Rx
FIFO and reset the pointer logic. This bit is self-clearing.
2 TX FIFO Reset 0 No impact on either of UART1 FIFOs. 0
1 Writing a logic 1 to U1FCR[2] will clear all bytes in UART1 TX
FIFO and reset the pointer logic. This bit is self-clearing.
5:3 - Reserved, user software should not write ones to reserved bits. NA
The value read from a reserved bit is not defined.
7:6 RX Trigger These two bits determine how many receiver UART1 FIFO 0
Level characters must be written before an interrupt is activated.
00 trigger level 0 (1 character or 0x01).
01 trigger level 1 (4 characters or 0x04).
10 trigger level 2 (8 characters or 0x08).
11 trigger level 3 (14 characters or 0x0E).

10.3.9 UART1 Line Control Register (U1LCR - 0xE001 000C)

The U1LCR determines the format of the data character that is to be transmitted or
received.

Table 124: UART1 Line Control Register (U1LCR - address 0xE001 000C) bit description
Bit Symbol Value Description Reset value
1:0 Word Length 00 5 bit character length. 0
Select 01 6 bit character length.
10 7 bit character length.
11 8 bit character length.
2 Stop Bit Select 0 1 stop bit. 0
1 2 stop bits (1.5 if U1LCR[1:0]=00).
3 Parity Enable 0 Disable parity generation and checking. 0
1 Enable parity generation and checking.

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Table 124: UART1 Line Control Register (U1LCR - address 0xE001 000C) bit description
Bit Symbol Value Description Reset value
5:4 Parity Select 00 Odd parity. Number of 1s in the transmitted character and the 0
attached parity bit will be odd.
01 Even Parity. Number of 1s in the transmitted character and the
attached parity bit will be even.
10 Forced "1" stick parity.
11 Forced "0" stick parity.
6 Break Control 0 Disable break transmission. 0
1 Enable break transmission. Output pin UART1 TXD is forced
to logic 0 when U1LCR[6] is active high.
7 Divisor Latch 0 Disable access to Divisor Latches. 0
Access Bit (DLAB) 1 Enable access to Divisor Latches.

10.3.10 UART1 Modem Control Register (U1MCR - 0xE001 0010)

This register is available in LPC2134, LPC2136, LPC2138, LPC2134/01, LPC2136/01,
and LPC2138/01 only.

The U1MCR enables the modem loopback mode and controls the modem output signals.

Table 125: UART1 Modem Control Register (U1MCR - address 0xE001 0010) bit description
Bit Symbol Value Description Reset value
0 DTR Control Source for modem output pin, DTR. This bit reads as 0 when 0
modem loopback mode is active.
1 RTS Control Source for modem output pin RTS. This bit reads as 0 when 0
modem loopback mode is active.
3:2 - Reserved, user software should not write ones to reserved bits. NA
The value read from a reserved bit is not defined.
4 Loopback Mode The modem loopback mode provides a mechanism to perform 0
Select diagnostic loopback testing. Serial data from the transmitter is
connected internally to serial input of the receiver. Input pin,
RXD1, has no effect on loopback and output pin, TXD1 is held
in marking state. The four modem inputs (CTS, DSR, RI and
DCD) are disconnected externally. Externally, the modem
outputs (RTS, DTR) are set inactive. Internally, the four modem
outputs are connected to the four modem inputs. As a result of
these connections, the upper four bits of the U1MSR will be
driven by the lower four bits of the U1MCR rather than the four
modem inputs in normal mode. This permits modem status
interrupts to be generated in loopback mode by writing the
lower four bits of U1MCR.
0 Disable modem loopback mode.
1 Enable modem loopback mode.
5:3 - Reserved, user software should not write ones to reserved bits. NA
The value read from a reserved bit is not defined.
6 RTSen[1] Auto-RTS control bit. 0
0 Disable auto-RTS flow control.
1 Enable auto-RTS flow control.

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Table 125: UART1 Modem Control Register (U1MCR - address 0xE001 0010) bit description
Bit Symbol Value Description Reset value
7 CTSen[1] Auto-CTS control bit. 0
0 Disable auto-CTS flow control.
1 Enable auto-CTS flow control.

[1] This feature is available in LPC213x/01 devices only.

10.3.10.1 Auto-flow control

This feature is available in LPC2134/01, LPC2136, LPC2138/01 devices only.

If auto-RTS mode is enabled the UART1‘s receiver FIFO hardware controls the RTS1
output of the UART1. If the auto-CTS mode is enabled the UART1‘s U1TSR hardware will
only start transmitting if the CTS1 input signal is asserted.

Auto-RTS

The auto-RTS function is enabled by setting the CTSen bit. Auto-RTS data flow control
originates in the U1RBR module and is linked to the programmed receiver FIFO trigger
level. If auto-RTS is enabled, when the receiver FIFO level reaches the programmed
trigger level RTS1 is deasserted (to a high value). The sending UART may send an
additional byte after the trigger level is reached (assuming the sending UART has another
byte to send) because it may not recognize the deassertion of RTS1 until after it has
begun sending the additional byte. RTS1 is automatically reasserted (to a low value) once
the receiver FIFO has reached the previous trigger level. The reassertion of RTS1 signals
the sending UART to continue transmitting data.

If auto-RTS mode is disabled the RTSen bit controls the RTS1 output of the UART1. If
auto-RTS mode is enabled hardware controls the RTS1 output and the actual value of
RTS1 will be copied in the RTSen bit of the UART1. As long as auto-RTS is enabled the
value if the RTSen bit is read-only for software.

Example: Suppose the UART1 operating in type 550 has trigger level in U1FCR set to 0x2
then if auto-RTS is enabled the UART1 will deassert the RTS1 output as soon as the
receive FIFO contains 8 bytes (Table 123 on page 118). The RTS1 output will be
reasserted as soon as the receive FIFO hits the previous trigger level: 4 bytes.

UART1 Rx
~
~

start byte N stop start bits0..7 stop start bits0..7 stop

~
~

RTS1 pin

UART1 Rx
FIFO read
~~
~ ~

UART1 Rx N-1 N N-1 N-2 N-1 N-2 M+2 M+1 M M-1

FIFO level
~
~

Fig 20. Auto-RTS functional timing

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Auto-CTS

The auto-CTS function is enabled by setting the CTSen bit. If auto-CTS is enabled the
transmitter circuitry in the U1TSR module checks CTS1 input before sending the next
data byte. When CTS1 is active (low), the transmitter sends the next byte. To stop the
transmitter from sending the following byte, CTS1 must be released before the middle of
the last stop bit that is currently being sent. In auto-CTS mode a change of the CTS1
signal does not trigger a modem status interrupt unless the CTS Interrupt Enable bit is set,
Delta CTS bit in the U1MSR will be set though. Table 126 lists the conditions for
generating a Modem Status interrupt.

Table 126. Modem status interrupt generation

Enable Modem CTSen CTS Interrupt Delta CTS Delta DCD or Modem Status
Status (U1MCR[7]) Enable (U1MSR[0]) Trailing Edge RI or Interrupt
Interrupt (U1IER[7]) Delta DSR
(U1IER[3]) (U1MSR[3] or U1MSR[2] or (U1MSR[1]))
0 x x x x no
1 0 x 0 0 no
1 0 x 1 x yes
1 0 x x 1 yes
1 1 0 x 0 no
1 1 0 x 1 yes
1 1 1 0 0 no
1 1 1 1 x yes
1 1 1 x 1 yes

The auto-CTS function reduces interrupts to the host system. When flow control is
enabled, a CTS1 state change does not trigger host interrupts because the device
automatically controls its own transmitter. Without auto-CTS, the transmitter sends any
data present in the transmit FIFO and a receiver overrun error can result. Figure 21
illustrates the auto-CTS functional timing.

UART1 TX
~
~

~
~

start bits0..7 stop start bits0..7 stop start bits0..7 stop

~
~

CTS1 pin
~
~

Fig 21. Auto-CTS functional timing

While starting transmission of the initial character the CTS1 signal is asserted.
Transmission will stall as soon as the pending transmission has completed. The UART will
continue transmitting a 1 bit as long as CTS1 is deasserted (high). As soon as CTS1 gets
deasserted transmission resumes and a start bit is sent followed by the data bits of the
next character.

10.3.11 UART1 Line Status Register (U1LSR - 0xE001 0014, Read Only)
The U1LSR is a read-only register that provides status information on the UART1 TX and
RX blocks.

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Table 127: UART1 Line Status Register (U1LSR - address 0xE001 0014, read only) bit description
Bit Symbol Value Description Reset
value
0 Receiver Data U1LSR[0] is set when the U1RBR holds an unread character and is cleared when 0
Ready the UART1 RBR FIFO is empty.
(RDR) 0 U1RBR is empty.
1 U1RBR contains valid data.
1 Overrun Error The overrun error condition is set as soon as it occurs. An U1LSR read clears 0
(OE) U1LSR[1]. U1LSR[1] is set when UART1 RSR has a new character assembled and
the UART1 RBR FIFO is full. In this case, the UART1 RBR FIFO will not be
overwritten and the character in the UART1 RSR will be lost.
0 Overrun error status is inactive.
1 Overrun error status is active.
2 Parity Error When the parity bit of a received character is in the wrong state, a parity error 0
(PE) occurs. An U1LSR read clears U1LSR[2]. Time of parity error detection is
dependent on U1FCR[0].
Note: A parity error is associated with the character at the top of the UART1 RBR
FIFO.
0 Parity error status is inactive.
1 Parity error status is active.
3 Framing Error When the stop bit of a received character is a logic 0, a framing error occurs. An 0
(FE) U1LSR read clears U1LSR[3]. The time of the framing error detection is dependent
on U1FCR0. Upon detection of a framing error, the RX will attempt to resynchronize
to the data and assume that the bad stop bit is actually an early start bit. However, it
cannot be assumed that the next received byte will be correct even if there is no
Framing Error.
Note: A framing error is associated with the character at the top of the UART1 RBR
FIFO.
0 Framing error status is inactive.
1 Framing error status is active.
4 Break Interrupt When RXD1 is held in the spacing state (all 0’s) for one full character transmission 0
(BI) (start, data, parity, stop), a break interrupt occurs. Once the break condition has
been detected, the receiver goes idle until RXD1 goes to marking state (all 1’s). An
U1LSR read clears this status bit. The time of break detection is dependent on
U1FCR[0].
Note: The break interrupt is associated with the character at the top of the UART1
RBR FIFO.
0 Break interrupt status is inactive.
1 Break interrupt status is active.
5 Transmitter THRE is set immediately upon detection of an empty UART1 THR and is cleared on 1
Holding a U1THR write.
Register Empty 0 U1THR contains valid data.
(THRE)
1 U1THR is empty.
6 Transmitter TEMT is set when both U1THR and U1TSR are empty; TEMT is cleared when 1
Empty either the U1TSR or the U1THR contain valid data.
(TEMT) 0 U1THR and/or the U1TSR contains valid data.
1 U1THR and the U1TSR are empty.

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Table 127: UART1 Line Status Register (U1LSR - address 0xE001 0014, read only) bit description
Bit Symbol Value Description Reset
value
7 Error in RX U1LSR[7] is set when a character with a RX error such as framing error, parity error 0
FIFO or break interrupt, is loaded into the U1RBR. This bit is cleared when the U1LSR
(RXFE) register is read and there are no subsequent errors in the UART1 FIFO.
0 U1RBR contains no UART1 RX errors or U1FCR[0]=0.
1 UART1 RBR contains at least one UART1 RX error.

10.3.12 UART1 Modem Status Register (U1MSR - 0xE001 0018)

This register is available in LPC2134, LPC2136, LPC2138, LPC2134/01, LPC2136/01,
and LPC2138/01 devices only.

The U1MSR is a read-only register that provides status information on the modem input
signals. U1MSR[3:0] is cleared on U1MSR read. Note that modem signals have no direct
affect on UART1 operation, they facilitate software implementation of modem signal
operations.

Table 128: UART1 Modem Status Register (U1MSR - address 0xE001 0018) bit description
Bit Symbol Value Description Reset value
0 Delta CTS Set upon state change of input CTS. Cleared on an U1MSR read. 0
0 No change detected on modem input, CTS.
1 State change detected on modem input, CTS.
1 Delta DSR Set upon state change of input DSR. Cleared on an U1MSR read. 0
0 No change detected on modem input, DSR.
1 State change detected on modem input, DSR.
2 Trailing Edge RI Set upon low to high transition of input RI. Cleared on an U1MSR read. 0
0 No change detected on modem input, RI.
1 Low-to-high transition detected on RI.
3 Delta DCD Set upon state change of input DCD. Cleared on an U1MSR read. 0
0 No change detected on modem input, DCD.
1 State change detected on modem input, DCD.
4 CTS Clear To Send State. Complement of input signal CTS. This bit is connected to 0
U1MCR[1] in modem loopback mode.
5 DSR Data Set Ready State. Complement of input signal DSR. This bit is connected 0
to U1MCR[0] in modem loopback mode.
6 RI Ring Indicator State. Complement of input RI. This bit is connected to 0
U1MCR[2] in modem loopback mode.
7 DCD Data Carrier Detect State. Complement of input DCD. This bit is connected to 0
U1MCR[3] in modem loopback mode.

10.3.13 UART1 Scratch pad register (U1SCR - 0xE001 001C)

The U1SCR has no effect on the UART1 operation. This register can be written and/or
read at user’s discretion. There is no provision in the interrupt interface that would indicate
to the host that a read or write of the U1SCR has occurred.

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Table 129: UART1 Scratch pad register (U1SCR - address 0xE001 0014) bit description
Bit Symbol Description Reset value
7:0 Pad A readable, writable byte. 0x00

10.3.14 UART1 Auto-baud Control Register (U1ACR - 0xE001 0020)

This feature is available in LPC213x/01 devices only.

The UART1 Auto-baud Control Register (U1ACR) controls the process of measuring the
incoming clock/data rate for the baud rate generation and can be read and written at
user’s discretion.

Table 130: Auto-baud Control Register (U1ACR - 0xE001 0020) bit description
Bit Symbol Value Description Reset value
0 Start This bit is automatically cleared after auto-baud 0
completion.
0 Auto-baud stop (auto-baud is not running).
1 Auto-baud start (auto-baud is running).Auto-baud run
bit. This bit is automatically cleared after auto-baud
completion.
1 Mode Auto-baud mode select bit. 0
0 Mode 0.
1 Mode 1.
2 AutoRestart 0 No restart 0
1 Restart in case of time-out (counter restarts at next
UART1 Rx falling edge)
7:3 - NA Reserved, user software should not write ones to 0
reserved bits. The value read from a reserved bit is not
defined.
8 ABEOIntClr End of auto-baud interrupt clear bit (write only 0
accessible). Writing a 1 will clear the corresponding
interrupt in the U1IIR. Writing a 0 has no impact.
9 ABTOIntClr Auto-baud time-out interrupt clear bit (write only 0
accessible). Writing a 1 will clear the corresponding
interrupt in the U1IIR. Writing a 0 has no impact.
31:10 - NA Reserved, user software should not write ones to 0
reserved bits. The value read from a reserved bit is not
defined.

10.3.15 Auto-baud
The UART1 auto-baud function can be used to measure the incoming baud-rate based on
the ”AT" protocol (Hayes command). If enabled the auto-baud feature will measure the bit
time of the receive data stream and set the divisor latch registers U1DLM and U1DLL
accordingly.

Auto-baud is started by setting the U1ACR Start bit. Auto-baud can be stopped by clearing
the U1ACR Start bit. The Start bit will clear once auto-baud has finished and reading the
bit will return the status of auto-baud (pending/finished).

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Two auto-baud measuring modes are available which can be selected by the U1ACR
Mode bit. In mode 0 the baud-rate is measured on two subsequent falling edges of the
UART1 Rx pin (the falling edge of the start bit and the falling edge of the least significant
bit). In mode 1 the baud-rate is measured between the falling edge and the subsequent
rising edge of the UART1 Rx pin (the length of the start bit).

The U1ACR AutoRestart bit can be used to automatically restart baud-rate measurement
if a time-out occurs (the rate measurement counter overflows). If this bit is set the rate
measurement will restart at the next falling edge of the UART1 Rx pin.

The auto-baud function can generate two interrupts.

• The U1IIR ABTOInt interrupt will get set if the interrupt is enabled (U1IER ABToIntEn
is set and the auto-baud rate measurement counter overflows).
• The U1IIR ABEOInt interrupt will get set if the interrupt is enabled (U1IER ABEOIntEn
is set and the auto-baud has completed successfully).

The auto-baud interrupts have to be cleared by setting the corresponding U1ACR

ABTOIntClr and ABEOIntEn bits.

Typically the fractional baud-rate generator is disabled (DIVADDVAL = 0) during

auto-baud. However, if the fractional baud-rate generator is enabled (DIVADDVAL > 0), it
is going to impact the measuring of UART1 Rx pin baud-rate, but the value of the U1FDR
register is not going to be modified after rate measurement. Also, when auto-baud is used,
any write to U1DLM and U1DLL registers should be done before U1ACR register write.
The minimum and the maximum baudrates supported by UART1 are function of PCLK,
number of data bits, stop-bits and parity bits.

(6)

2 × P CLK PCLK
ratemin = ------------------------- ≤ UART 1 baudrate ≤ ------------------------------------------------------------------------------------------------------------ = ratemax
16 × 2 15 16 × ( 2 + databits + paritybits + stopbits )

10.3.16 Auto-baud Modes

When the software is expecting an ”AT" command, it configures the UART1 with the
expected character format and sets the U1ACR Start bit. The initial values in the divisor
latches U1DLM and U1DLM don‘t care. Because of the ”A" or ”a" ASCII coding
(”A" = 0x41, ”a" = 0x61), the UART1 Rx pin sensed start bit and the LSB of the expected
character are delimited by two falling edges. When the U1ACR Start bit is set, the
auto-baud protocol will execute the following phases:

1. On U1ACR Start bit setting, the baud-rate measurement counter is reset and the
UART1 U1RSR is reset. The U1RSR baud rate is switch to the highest rate.
2. A falling edge on UART1 Rx pin triggers the beginning of the start bit. The rate
measuring counter will start counting PCLK cycles optionally pre-scaled by the
fractional baud-rate generator.
3. During the receipt of the start bit, 16 pulses are generated on the RSR baud input with
the frequency of the (fractional baud-rate pre-scaled) UART1 input clock,
guaranteeing the start bit is stored in the U1RSR.
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4. During the receipt of the start bit (and the character LSB for mode = 0) the rate
counter will continue incrementing with the pre-scaled UART1 input clock (PCLK).
5. If Mode = 0 then the rate counter will stop on next falling edge of the UART1 Rx pin. If
Mode = 1 then the rate counter will stop on the next rising edge of the UART1 Rx pin.
6. The rate counter is loaded into U1DLM/U1DLL and the baud-rate will be switched to
normal operation. After setting the U1DLM/U1DLL the end of auto-baud interrupt
U1IIR ABEOInt will be set, if enabled. The U1RSR will now continue receiving the
remaining bits of the ”A/a" character.

'A' (0x41) or 'a' (0x61)

start bit0 bit1 bit2 bit3 bit4 bit5 bit6 bit7 parity stop

UART1 RX
start bit LSB of 'A' or 'a'

U1ACR start

rate counter

16xbaud_rate
16 cycles 16 cycles

a. Mode 0 (start bit and LSB are used for auto-baud)

'A' (0x41) or 'a' (0x61)

start bit0 bit1 bit2 bit3 bit4 bit5 bit6 bit7 parity stop

UART1 RX
start bit LSB of 'A' or 'a'

U1ACR start

rate counter

16xbaud_rate
16 cycles

b. Mode 1 (only start bit is used for auto-baud)

Fig 22. Autobaud a) mode 0 and b) mode 1 waveform.

10.3.17 UART1 Transmit Enable Register (U1TER - 0xE001 0030)

LPC213x’s U1TER enables implementation of software and hardware flow control. When
TXEn=1, UART1 transmitter will keep sending data as long as they are available. As soon
as TXEn becomes 0, UART1 transmission will stop.

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Table 131 describes how to use TXEn bit in order to achieve software flow control.

Table 131: UART1 Transmit Enable Register (U1TER - address 0xE001 0030) bit description
Bit Symbol Description Reset value
6:0 - Reserved, user software should not write ones to reserved bits. NA
The value read from a reserved bit is not defined.
7 TXEN When this bit is 1, as it is after a Reset, data written to the THR 1
is output on the TXD pin as soon as any preceding data has
been sent. If this bit cleared to 0 while a character is being sent,
the transmission of that character is completed, but no further
characters are sent until this bit is set again. In other words, a 0
in this bit blocks the transfer of characters from the THR or TX
FIFO into the transmit shift register. Software can clear this bit
when it detects that the a hardware-handshaking TX-permit
signal (LPC2134/6/8 and matching /01: CTS - otherwise any
GPIO/external interrupt line) has gone false, or with software
handshaking, when it receives an XOFF character (DC3).
Software can set this bit again when it detects that the
TX-permit signal has gone true, or when it receives an XON
(DC1) character.

10.4 Architecture
The architecture of the UART1 is shown below in the block diagram.

The APB interface provides a communications link between the CPU or host and the
UART1.

The UART1 receiver block, U1RX, monitors the serial input line, RXD1, for valid input.
The UART1 RX Shift Register (U1RSR) accepts valid characters via RXD1. After a valid
character is assembled in the U1RSR, it is passed to the UART1 RX Buffer Register FIFO
to await access by the CPU or host via the generic host interface.

The UART1 transmitter block, U1TX, accepts data written by the CPU or host and buffers
the data in the UART1 TX Holding Register FIFO (U1THR). The UART1 TX Shift Register
(U1TSR) reads the data stored in the U1THR and assembles the data to transmit via the
serial output pin, TXD1.

The UART1 Baud Rate Generator block, U1BRG, generates the timing enables used by
the UART1 TX block. The U1BRG clock input source is the APB clock (PCLK). The main
clock is divided down per the divisor specified in the U1DLL and U1DLM registers. This
divided down clock is a 16x oversample clock, NBAUDOUT.

The modem interface contains registers U1MCR and U1MSR. This interface is
responsible for handshaking between a modem peripheral and the UART1.

The interrupt interface contains registers U1IER and U1IIR. The interrupt interface
receives several one clock wide enables from the U1TX and U1RX blocks.

Status information from the U1TX and U1RX is stored in the U1LSR. Control information
for the U1TX and U1RX is stored in the U1LCR.

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MODEM U1TX
NTXRDY

TXD1
U1THR U1TSR
CTS

DSR U1MSR

RI
U1BRG
DCD
DTR
U1DLL NBAUDOUT
RTS
U1MCR
U1DLM RCLK

U1RX NRXRDY
INTERRUPT
RXD1
U1RBR U1RSR

U1INTR U1IER

U1IIR
U1FCR

U1LSR
U1SCR

U1LCR

PA[2:0]

PSEL

PSTB

PWRITE

APB
PD[7:0] INTERFACE DDIS

PCLK

Fig 23. UART1 block diagram

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Chapter 11: LPC213x SPI
Rev. 3 — 4 October 2010 User manual

11.1 Features
• Single complete and independent SPI controller.
• Compliant with Serial Peripheral Interface (SPI) specification.
• Synchronous, Serial, Full Duplex Communication.
• Combined SPI master and slave.
• Maximum data bit rate of one eighth of the input clock rate.
• 8 to 16 bits per transfer

11.2 Description

11.2.1 SPI overview

SPI is a full duplex serial interface. It can handle multiple masters and slaves being
connected to a given bus. Only a single master and a single slave can communicate on
the interface during a given data transfer. During a data transfer the master always sends
8 to 16 bits of data to the slave, and the slave always sends a matching number of bits to
the master.

11.2.2 SPI data transfers

Figure 24 is a timing diagram that illustrates the four different data transfer formats that
are available with the SPI. This timing diagram illustrates a single 8 bit data transfer. The
first thing you should notice in this timing diagram is that it is divided into three horizontal
parts. The first part describes the SCK and SSEL signals. The second part describes the
MOSI and MISO signals when the CPHA variable is 0. The third part describes the MOSI
and MISO signals when the CPHA variable is 1.

In the first part of the timing diagram, note two points. First, the SPI is illustrated with
CPOL set to both 0 and 1. The second point to note is the activation and de-activation of
the SSEL signal. When CPHA = 0, the SSEL signal will always go inactive between data
transfers. This is not guaranteed when CPHA = 1 (the signal can remain active).

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SCK (CPOL = 0)

SCK (CPOL = 1)

SSEL

CPHA = 0

Cycle # CPHA = 0 1 2 3 4 5 6 7 8

MOSI (CPHA = 0) BIT 1 BIT 2 BIT 3 BIT 4 BIT 5 BIT 6 BIT 7 BIT 8

MISO (CPHA = 0) BIT 1 BIT 2 BIT 3 BIT 4 BIT 5 BIT 6 BIT 7 BIT 8

CPHA = 1

Cycle # CPHA = 1 1 2 3 4 5 6 7 8

MOSI (CPHA = 1) BIT 1 BIT 2 BIT 3 BIT 4 BIT 5 BIT 6 BIT 7 BIT 8

MISO (CPHA = 1) BIT 1 BIT 2 BIT 3 BIT 4 BIT 5 BIT 6 BIT 7 BIT 8

Fig 24. SPI data transfer format (CPHA = 0 and CPHA = 1)

The data and clock phase relationships are summarized in Table 132. This table
summarizes the following for each setting of CPOL and CPHA.

• When the first data bit is driven

• When all other data bits are driven
• When data is sampled
Table 132. SPI data to clock phase relationship
CPOL CPHA First data driven Other data driven Data sampled
0 0 Prior to first SCK rising edge SCK falling edge SCK rising edge
0 1 First SCK rising edge SCK rising edge SCK falling edge
1 0 Prior to first SCK falling edge SCK rising edge SCK falling edge
1 1 First SCK falling edge SCK falling edge SCK rising edge

The definition of when an 8 bit transfer starts and stops is dependent on whether a device
is a master or a slave, and the setting of the CPHA variable.

When a device is a master, the start of a transfer is indicated by the master having a byte
of data that is ready to be transmitted. At this point, the master can activate the clock, and
begin the transfer. The transfer ends when the last clock cycle of the transfer is complete.

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When a device is a slave, and CPHA is set to 0, the transfer starts when the SSEL signal
goes active, and ends when SSEL goes inactive. When a device is a slave, and CPHA is
set to 1, the transfer starts on the first clock edge when the slave is selected, and ends on
the last clock edge where data is sampled.

11.2.3 General information

There are four registers that control the SPI peripheral. They are described in detail in
Section 11.4 “Register description” on page 133.

The SPI control register contains a number of programmable bits used to control the
function of the SPI block. The settings for this register must be set up prior to a given data
transfer taking place.

The SPI status register contains read only bits that are used to monitor the status of the
SPI interface, including normal functions, and exception conditions. The primary purpose
of this register is to detect completion of a data transfer. This is indicated by the SPIF bit.
The remaining bits in the register are exception condition indicators. These exceptions will
be described later in this section.

The SPI data register is used to provide the transmit and receive data bytes. An internal
shift register in the SPI block logic is used for the actual transmission and reception of the
serial data. Data is written to the SPI data register for the transmit case. There is no buffer
between the data register and the internal shift register. A write to the data register goes
directly into the internal shift register. Therefore, data should only be written to this register
when a transmit is not currently in progress. Read data is buffered. When a transfer is
complete, the receive data is transferred to a single byte data buffer, where it is later read.
A read of the SPI data register returns the value of the read data buffer.

The SPI clock counter register controls the clock rate when the SPI block is in master
mode. This needs to be set prior to a transfer taking place, when the SPI block is a
master. This register has no function when the SPI block is a slave.

The I/Os for this implementation of SPI are standard CMOS I/Os. The open drain SPI
option is not implemented in this design. When a device is set up to be a slave, its I/Os are
only active when it is selected by the SSEL signal being active.

11.2.4 Master operation

The following sequence describes how one should process a data transfer with the SPI
block when it is set up to be the master. This process assumes that any prior data transfer
has already completed.

1. Set the SPI clock counter register to the desired clock rate.
2. Set the SPI control register to the desired settings.
3. Write the data to transmitted to the SPI data register. This write starts the SPI data
transfer.
4. Wait for the SPIF bit in the SPI status register to be set to 1. The SPIF bit will be set
after the last cycle of the SPI data transfer.
5. Read the SPI status register.
6. Read the received data from the SPI data register (optional).
7. Go to step 3 if more data is required to transmit.
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Note that a read or write of the SPI data register is required in order to clear the SPIF
status bit. Therefore, if the optional read of the SPI data register does not take place, a
write to this register is required in order to clear the SPIF status bit.

11.2.5 Slave operation

The following sequence describes how one should process a data transfer with the SPI
block when it is set up to be a slave. This process assumes that any prior data transfer
has already completed. It is required that the system clock driving the SPI logic be at least
8X faster than the SPI.

1. Set the SPI control register to the desired settings.

2. Write the data to transmitted to the SPI data register (optional). Note that this can only
be done when a slave SPI transfer is not in progress.
3. Wait for the SPIF bit in the SPI status register to be set to 1. The SPIF bit will be set
after the last sampling clock edge of the SPI data transfer.
4. Read the SPI status register.
5. Read the received data from the SPI data register (optional).
6. Go to step 2 if more data is required to transmit.

Note that a read or write of the SPI data register is required in order to clear the SPIF
status bit. Therefore, at least one of the optional reads or writes of the SPI data register
must take place, in order to clear the SPIF status bit.

11.2.6 Exception conditions

Read Overrun

A read overrun occurs when the SPI block internal read buffer contains data that has not
been read by the processor, and a new transfer has completed. The read buffer
containing valid data is indicated by the SPIF bit in the status register being active. When
a transfer completes, the SPI block needs to move the received data to the read buffer. If
the SPIF bit is active (the read buffer is full), the new receive data will be lost, and the read
overrun (ROVR) bit in the status register will be activated.

Write Collision

As stated previously, there is no write buffer between the SPI block bus interface, and the
internal shift register. As a result, data must not be written to the SPI data register when a
SPI data transfer is currently in progress. The time frame where data cannot be written to
the SPI data register is from when the transfer starts, until after the status register has
been read when the SPIF status is active. If the SPI data register is written in this time
frame, the write data will be lost, and the write collision (WCOL) bit in the status register
will be activated.

Mode Fault

The SSEL signal must always be inactive when the SPI block is a master. If the SSEL
signal goes active, when the SPI block is a master, this indicates another master has
selected the device to be a slave. This condition is known as a mode fault. When a mode
fault is detected, the mode fault (MODF) bit in the status register will be activated, the SPI
signal drivers will be de-activated, and the SPI mode will be changed to be a slave.

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Slave Abort

A slave transfer is considered to be aborted, if the SSEL signal goes inactive before the
transfer is complete. In the event of a slave abort, the transmit and receive data for the
transfer that was in progress are lost, and the slave abort (ABRT) bit in the status register
will be activated.

11.3 Pin description

Table 133. SPI pin description
Pin Name Type Pin Description
SCK0 Input/Output Serial Clock. The SPI is a clock signal used to synchronize the transfer of data across the
SPI interface. The SPI is always driven by the master and received by the slave. The clock is
programmable to be active high or active low. The SPI is only active during a data transfer.
Any other time, it is either in its inactive state, or tri-stated.
SSEL0 Input Slave Select. The SPI slave select signal is an active low signal that indicates which slave is
currently selected to participate in a data transfer. Each slave has its own unique slave select
signal input. The SSEL must be low before data transactions begin and normally stays low
for the duration of the transaction. If the SSEL signal goes high any time during a data
transfer, the transfer is considered to be aborted. In this event, the slave returns to idle, and
any data that was received is thrown away. There are no other indications of this exception.
This signal is not directly driven by the master. It could be driven by a simple general purpose
I/O under software control.
On the LPC213x (unlike earlier Philips ARM devices) the SSEL0 pin can be used for a
different function when the SPI0 interface is only used in Master mode. For example, pin
hosting the SSEL0 function can be configured as an output digital GPIO pin and used to
select one of the SPI0 slaves.
MISO0 Input/Output Master In Slave Out. The MISO signal is a unidirectional signal used to transfer serial data
from the slave to the master. When a device is a slave, serial data is output on this signal.
When a device is a master, serial data is input on this signal. When a slave device is not
selected, the slave drives the signal high impedance.
MOSI0 Input/Output Master Out Slave In. The MOSI signal is a unidirectional signal used to transfer serial data
from the master to the slave. When a device is a master, serial data is output on this signal.
When a device is a slave, serial data is input on this signal.

11.4 Register description

The SPI contains 5 registers as shown in Table 134. All registers are byte, half word and
word accessible.

Table 134. SPI register map

Name Description Access Reset Address
value[1]
S0SPCR SPI Control Register. This register controls the R/W 0x00 0xE002 0000
operation of the SPI.
S0SPSR SPI Status Register. This register shows the RO 0x00 0xE002 0004
status of the SPI.

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Table 134. SPI register map

Name Description Access Reset Address
value[1]
S0SPDR SPI Data Register. This bi-directional register R/W 0x00 0xE002 0008
provides the transmit and receive data for the
SPI. Transmit data is provided to the SPI0 by
writing to this register. Data received by the SPI0
can be read from this register.
S0SPCCR SPI Clock Counter Register. This register R/W 0x00 0xE002 000C
controls the frequency of a master’s SCK0.
S0SPINT SPI Interrupt Flag. This register contains the R/W 0x00 0xE002 001C
interrupt flag for the SPI interface.

[1] Reset value reflects the data stored in used bits only. It does not include reserved bits content.

11.4.1 SPI Control Register (S0SPCR - 0xE002 0000)

The S0SPCR register controls the operation of the SPI0 as per the configuration bits
setting.

Table 135: SPI Control Register (S0SPCR - address 0xE002 0000) bit description
Bit Symbol Value Description Reset
value
1:0 - Reserved, user software should not write ones to NA
reserved bits. The value read from a reserved bit is not
defined.
2 BitEnable 0 The SPI controller sends and receives 8 bits of data per 0
transfer.
1 The SPI controller sends and receives the number of bits
selected by bits 11:8.
3 CPHA Clock phase control determines the relationship between 0
the data and the clock on SPI transfers, and controls
when a slave transfer is defined as starting and ending.
Data is sampled on the first (leading) clock edge of SCK.
0 A transfer starts and ends with activation and
deactivation of the SSEL signal.
1 Data is sampled on the second (trailing) clock edge of the
SCK. A transfer starts with the first clock edge, and ends
with the last sampling edge when the SSEL signal is
active.
4 CPOL Clock polarity control. 0
0 SCK is active high.
1 SCK is active low.
5 MSTR Master mode select. 0
0 The SPI operates in Slave mode.
1 The SPI operates in Master mode.
6 LSBF LSB First controls which direction each byte is shifted 0
when transferred.
0 SPI data is transferred MSB (bit 7) first.
1 SPI data is transferred LSB (bit 0) first.

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Table 135: SPI Control Register (S0SPCR - address 0xE002 0000) bit description
Bit Symbol Value Description Reset
value
7 SPIE Serial peripheral interrupt enable. 0
0 SPI interrupts are inhibited.
1 A hardware interrupt is generated each time the SPIF or
MODF bits are activated.
11:8 BITS When bit 2 of this register is 1, this field controls the 0000
number of bits per transfer:
1000 8 bits per transfer
1001 9 bits per transfer
1010 10 bits per transfer
1011 11 bits per transfer
1100 12 bits per transfer
1101 13 bits per transfer
1110 14 bits per transfer
1111 15 bits per transfer
0000 16 bits per transfer
15:12 - Reserved, user software should not write ones to NA
reserved bits. The value read from a reserved bit is not
defined.

11.4.2 SPI Status Register (S0SPSR - 0xE002 0004)

The S0SPSR register controls the operation of the SPI0 as per the configuration bits
setting.

Table 136: SPI Status Register (S0SPSR - address 0xE002 0004) bit description
Bit Symbol Description Reset value
2:0 - Reserved, user software should not write ones to reserved bits. NA
The value read from a reserved bit is not defined.
3 ABRT Slave abort. When 1, this bit indicates that a slave abort has 0
occurred. This bit is cleared by reading this register.
4 MODF Mode fault. when 1, this bit indicates that a Mode fault error has 0
occurred. This bit is cleared by reading this register, then writing
the SPI control register.
5 ROVR Read overrun. When 1, this bit indicates that a read overrun has 0
occurred. This bit is cleared by reading this register.
6 WCOL Write collision. When 1, this bit indicates that a write collision has 0
occurred. This bit is cleared by reading this register, then
accessing the SPI data register.
7 SPIF SPI transfer complete flag. When 1, this bit indicates when a SPI 0
data transfer is complete. When a master, this bit is set at the
end of the last cycle of the transfer. When a slave, this bit is set
on the last data sampling edge of the SCK. This bit is cleared by
first reading this register, then accessing the SPI data register.
Note: this is not the SPI interrupt flag. This flag is found in the
SPINT register.

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11.4.3 SPI Data Register (S0SPDR - 0xE002 0008)

This bi-directional data register provides the transmit and receive data for the SPI.
Transmit data is provided to the SPI by writing to this register. Data received by the SPI
can be read from this register. When a master, a write to this register will start a SPI data
transfer. Writes to this register will be blocked from when a data transfer starts to when the
SPIF status bit is set, and the status register has not been read.

Table 137: SPI Data Register (S0SPDR - address 0xE002 0008) bit description
Bit Symbol Description Reset value
7:0 DataLow SPI Bi-directional data port. 0x00
15:8 DataHigh If bit 2 of the SPCR is 1 and bits 11:8 are other than 1000, some 0x00
or all of these bits contain the additional transmit and receive
bits. When less than 16 bits are selected, the more significant
among these bits read as zeroes.

11.4.4 SPI Clock Counter Register (S0SPCCR - 0xE002 000C)

This register controls the frequency of a master’s SCK. The register indicates the number
of PCLK cycles that make up an SPI clock. The value of this register must always be an
even number. As a result, bit 0 must always be 0. The value of the register must also
always be greater than or equal to 8. Violations of this can result in unpredictable
behavior.

Table 138: SPI Clock Counter Register (S0SPCCR - address 0xE002 000C) bit description
Bit Symbol Description Reset value
7:0 Counter SPI0 Clock counter setting. 0x00

The SPI0 rate may be calculated as: PCLK / SPCCR0 value. The PCLK rate is
CCLK /APB divider rate as determined by the APBDIV register contents.

11.4.5 SPI Interrupt register (S0SPINT - 0xE002 001C)

This register contains the interrupt flag for the SPI0 interface.

Table 139: SPI Interrupt register (S0SPINT - address 0xE002 001C) bit description
Bit Symbol Description Reset
value
0 SPI Interrupt SPI interrupt flag. Set by the SPI interface to generate an interrupt. 0
Flag Cleared by writing a 1 to this bit.
Note: this bit will be set once when SPIE = 1 and at least one of
SPIF and MODF bits changes from 0 to 1. However, only when the
SPI Interrupt bit is set and SPI Interrupt is enabled in the VIC, SPI
based interrupt can be processed by interrupt handling software.
7:1 - Reserved, user software should not write ones to reserved bits. The NA
value read from a reserved bit is not defined.

11.5 Architecture
The block diagram of the SPI solution implemented in SPI0 interface is shown in the
Figure 25.

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MOSI_IN
MOSI_OUT
MISO_IN
MISO_OUT

SPI SHIFT REGISTER

SCK_IN
SCK_OUT
SS_IN
SPI CLOCK
GENERATOR &
SPI Interrupt DETECTOR

SPI REGISTER
APB Bus INTERFACE

SPI STATE CONTROL

SCK_OUT_EN
MOSI_OUT_EN
MISO_OUT_EN
OUTPUT
ENABLE
LOGIC

Fig 25. SPI block diagram

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12.1 Features
• Compatible with Motorola SPI, 4-wire TI SSI, and National Semiconductor Microwire
buses.
• Synchronous Serial Communication
• Master or slave operation
• 8-frame FIFOs for both transmit and receive.
• 4 to 16 bits frame
• Maximum bit rate of PCLK/2 in master mode and PCLK/12 in slave mode.

12.2 Description
The SSP is a Synchronous Serial Port (SSP) controller capable of operation on a SPI,
4-wire SSI, or Microwire bus. It can interact with multiple masters and slaves on the bus.
Only a single master and a single slave can communicate on the bus during a given data
transfer. Data transfers are in principle full duplex, with frames of 4 to 16 bits of data
flowing from the master to the slave and from the slave to the master. In practice it is often
the case that only one of these data flows carries meaningful data.

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Table 140. SSP pin descriptions

Interface pin name/function
Pin Name Type Pin Description
SPI SSI Microwire
SCK1 I/O SCK CLK SK Serial Clock. SCK/CLK/SK is a clock signal used to
synchronize the transfer of data. It is driven by the master
and received by the slave. When SPI interface is used the
clock is programmable to be active high or active low,
otherwise it is always active high. SCK1 only switches
during a data transfer. Any other time, the SSP either holds
it in its inactive state, or does not drive it (leaves it in high
impedance state).
SSEL1 I/O SSEL FS CS Slave Select/Frame Sync/Chip Select. When the SSP is a
bus master, it drives this signal from shortly before the start
of serial data, to shortly after the end of serial data, to signify
a data transfer as appropriate for the selected bus and
mode. When the SSP is a bus slave, this signal qualifies the
presence of data from the Master, according to the protocol
in use. When there is just one bus master and one bus
slave, the Frame Sync or Slave Select signal from the
Master can be connected directly to the slave’s
corresponding input. When there is more than one slave on
the bus, further qualification of their Frame Select/Slave
Select inputs will typically be necessary to prevent more
than one slave from responding to a transfer.
MISO1 I/O MISO DR(M) SI(M) Master In Slave Out. The MISO signal transfers serial data
DX(S) SO(S) from the slave to the master. When the SSP is a slave, serial
data is output on this signal. When the SSP is a master, it
clocks in serial data from this signal. When the SSP is a
slave and is not selected by SSEL, it does not drive this
signal (leaves it in high impedance state).
MOSI1 I/O MOSI DX(M) SO(M) Master Out Slave In. The MOSI signal transfers serial data
DR(S) SI(S) from the master to the slave. When the SSP is a master, it
outputs serial data on this signal. When the SSP is a slave,
it clocks in serial data from this signal.

12.3 Bus description

12.3.1 Texas Instruments Synchronous Serial (SSI) frame format

Figure 26 shows the 4-wire Texas Instruments synchronous serial frame format supported
by the SSP module.

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CLK

FS
DX/DR MSB LSB

4 to 16 bits

a. Single frame transfer

CLK

FS
DX/DR MSB LSB MSB LSB

4 to 16 bits 4 to 16 bits

b. Continuous/back-to-back frames transfer

Fig 26. Texas Instruments synchronous serial frame format: a) single frame transfer and b)
continuous/back-to-back two frames.

For device configured as a master in this mode, CLK and FS are forced LOW, and the
transmit data line DX is tristated whenever the SSP is idle. Once the bottom entry of the
transmit FIFO contains data, FS is pulsed HIGH for one CLK period. The value to be
transmitted is also transferred from the transmit FIFO to the serial shift register of the
transmit logic. On the next rising edge of CLK, the MSB of the 4 to 16-bit data frame is
shifted out on the DX pin. Likewise, the MSB of the received data is shifted onto the DR
pin by the off-chip serial slave device.

Both the SSP and the off-chip serial slave device then clock each data bit into their serial
shifter on the falling edge of each CLK. The received data is transferred from the serial
shifter to the receive FIFO on the first rising edge of CLK after the LSB has been latched.

12.3.2 SPI frame format

The SPI interface is a four-wire interface where the SSEL signal behaves as a slave
select. The main feature of the SPI format is that the inactive state and phase of the SCK
signal are programmable through the CPOL and CPHA bits within the SSPCR0 control
register.

12.3.3 Clock Polarity (CPOL) and Clock Phase (CPHA) control

When the CPOL clock polarity control bit is LOW, it produces a steady state low value on
the SCK pin. If the CPOL clock polarity control bit is HIGH, a steady state high value is
placed on the CLK pin when data is not being transferred.

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The CPHA control bit selects the clock edge that captures data and allows it to change
state. It has the most impact on the first bit transmitted by either allowing or not allowing a
clock transition before the first data capture edge. When the CPHA phase control bit is
LOW, data is captured on the first clock edge transition. If the CPHA clock phase control
bit is HIGH, data is captured on the second clock edge transition.

12.3.4 SPI format with CPOL=0,CPHA=0

Single and continuous transmission signal sequences for SPI format with CPOL = 0,
CPHA = 0 are shown in Figure 28.

SCK
SSEL

MSB LSB
MOSI

MISO MSB LSB Q

4 to 16 bits

a. Single transfer with CPOL=0 and CPHA=0

SCK
SSEL

MOSI MSB LSB MSB LSB

MISO MSB LSB Q MSB LSB Q

4 to 16 bits 4 to 16 bits

b. Continuous transfer with CPOL=0 and CPHA=0

Fig 27. Motorola SPI frame format with CPOL=0 and CPHA=0 ( a) single transfer and b) continuous transfer)

In this configuration, during idle periods:

• The CLK signal is forced LOW

One half SCK period later, valid master data is transferred to the MOSI pin. Now that both
the master and slave data have been set, the SCK master clock pin goes HIGH after one
further half SCK period.

The data is now captured on the rising and propagated on the falling edges of the SCK
signal.

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In the case of a single word transmission, after all bits of the data word have been
transferred, the SSEL line is returned to its idle HIGH state one SCK period after the last
bit has been captured.

However, in the case of continuous back-to-back transmissions, the SSEL signal must be
pulsed HIGH between each data word transfer. This is because the slave select pin
freezes the data in its serial peripheral register and does not allow it to be altered if the
CPHA bit is logic zero. Therefore the master device must raise the SSEL pin of the slave
device between each data transfer to enable the serial peripheral data write. On
completion of the continuous transfer, the SSEL pin is returned to its idle state one SCK
period after the last bit has been captured.

12.3.5 SPI format with CPOL=0,CPHA=1

The transfer signal sequence for SPI format with CPOL = 0, CPHA = 1 is shown in
Figure 28, which covers both single and continuous transfers.

SCK
SSEL

MSB LSB
MOSI
MISO Q MSB LSB Q

4 to 16 bits

Fig 28. SPI frame format with CPOL=0 and CPHA=1

In this configuration, during idle periods:

• The CLK signal is forced LOW

• SSEL is forced HIGH
• The transmit MOSI/MISO pad is in high impedance
If the SSP is enabled and there is valid data within the transmit FIFO, the start of
transmission is signified by the SSEL master signal being driven LOW. Master’s MOSI pin
is enabled. After a further one half SCK period, both master and slave valid data is
enabled onto their respective transmission lines. At the same time, the SCK is enabled
with a rising edge transition.

Data is then captured on the falling edges and propagated on the rising edges of the SCK
signal.

In the case of a single word transfer, after all bits have been transferred, the SSEL line is
returned to its idle HIGH state one SCK period after the last bit has been captured.

For continuous back-to-back transfers, the SSEL pin is held LOW between successive
data words and termination is the same as that of the single word transfer.

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12.3.6 SPI format with CPOL = 1,CPHA = 0

Single and continuous transmission signal sequences for SPI format with CPOL=1,
CPHA=0 are shown in Figure 29.

SCK

SSEL

MSB LSB
MOSI

MISO MSB LSB Q

4 to 16 bits

a. Single transfer with CPOL=1 and CPHA=0

SCK

SSEL

MOSI MSB LSB MSB LSB

MISO MSB LSB Q MSB LSB Q

4 to 16 bits 4 to 16 bits

b. Continuous transfer with CPOL=1 and CPHA=0

Fig 29. SPI frame format with CPOL = 1 and CPHA = 0 ( a) single and b) continuous transfer)

In this configuration, during idle periods:

• The CLK signal is forced HIGH

• SSEL is forced HIGH
• The transmit MOSI/MISO pad is in high impedance
If the SSP is enabled and there is valid data within the transmit FIFO, the start of
transmission is signified by the SSEL master signal being driven LOW, which causes
slave data to be immediately transferred onto the MISO line of the master. Master’s MOSI
pin is enabled.

One half period later, valid master data is transferred to the MOSI line. Now that both the
master and slave data have been set, the SCK master clock pin becomes LOW after one
further half SCK period. This means that data is captured on the falling edges and be
propagated on the rising edges of the SCK signal.

In the case of a single word transmission, after all bits of the data word are transferred, the
SSEL line is returned to its idle HIGH state one SCK period after the last bit has been
captured.

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CPHA bit is logic zero. Therefore the master device must raise the SSEL pin of the slave
device between each data transfer to enable the serial peripheral data write. On
completion of the continuous transfer, the SSEL pin is returned to its idle state one SCK
period after the last bit has been captured.

12.3.7 SPI format with CPOL = 1,CPHA = 1

The transfer signal sequence for SPI format with CPOL = 1, CPHA = 1 is shown in
Figure 30, which covers both single and continuous transfers.

SCK

SSEL

MSB LSB
MOSI
MISO Q MSB LSB Q

4 to 16 bits

Fig 30. SPI frame format with CPOL = 1 and CPHA = 1

In this configuration, during idle periods:

• The CLK signal is forced HIGH

• SSEL is forced HIGH
• The transmit MOSI/MISO pad is in high impedance
If the SSP is enabled and there is valid data within the transmit FIFO, the start of
transmission is signified by the SSEL master signal being driven LOW. Master’s MOSI is
enabled. After a further one half SCK period, both master and slave data are enabled onto
their respective transmission lines. At the same time, the SCK is enabled with a falling
edge transition. Data is then captured on the rising edges and propagated on the falling
edges of the SCK signal.

After all bits have been transferred, in the case of a single word transmission, the SSEL
line is returned to its idle HIGH state one SCK period after the last bit has been captured.
For continuous back-to-back transmissions, the SSEL pins remains in its active LOW
state, until the final bit of the last word has been captured, and then returns to its idle state
as described above. In general, for continuous back-to-back transfers the SSEL pin is
held LOW between successive data words and termination is the same as that of the
single word transfer.

12.3.8 Semiconductor Microwire frame format

Figure 31 shows the Microwire frame format for a single frame. Figure 44 shows the same
format when back-to-back frames are transmitted.

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SK
CS

MSB LSB
SO
8 bit control
SI 0 MSB LSB

4 to 16 bits
output data

Fig 31. Microwire frame format (single transfer)

Microwire format is very similar to SPI format, except that transmission is half-duplex
instead of full-duplex, using a master-slave message passing technique. Each serial
transmission begins with an 8-bit control word that is transmitted from the SSP to the
off-chip slave device. During this transmission, no incoming data is received by the SSP.
After the message has been sent, the off-chip slave decodes it and, after waiting one
serial clock after the last bit of the 8-bit control message has been sent, responds with the
required data. The returned data is 4 to 16 bits in length, making the total frame length
anywhere from 13 to 25 bits.

In this configuration, during idle periods:

• The SK signal is forced LOW

• CS is forced HIGH
• The transmit data line SO is arbitrarily forced LOW
A transmission is triggered by writing a control byte to the transmit FIFO.The falling edge
of CS causes the value contained in the bottom entry of the transmit FIFO to be
transferred to the serial shift register of the transmit logic, and the MSB of the 8-bit control
frame to be shifted out onto the SO pin. CS remains LOW for the duration of the frame
transmission. The SI pin remains tristated during this transmission.

The off-chip serial slave device latches each control bit into its serial shifter on the rising
edge of each SK. After the last bit is latched by the slave device, the control byte is
decoded during a one clock wait-state, and the slave responds by transmitting data back
to the SSP. Each bit is driven onto SI line on the falling edge of SK. The SSP in turn
latches each bit on the rising edge of SK. At the end of the frame, for single transfers, the
CS signal is pulled HIGH one clock period after the last bit has been latched in the receive
serial shifter, that causes the data to be transferred to the receive FIFO.

Note: The off-chip slave device can tristate the receive line either on the falling edge of
SK after the LSB has been latched by the receive shiftier, or when the CS pin goes HIGH.

For continuous transfers, data transmission begins and ends in the same manner as a
single transfer. However, the CS line is continuously asserted (held LOW) and
transmission of data occurs back to back. The control byte of the next frame follows
directly after the LSB of the received data from the current frame. Each of the received
values is transferred from the receive shifter on the falling edge SK, after the LSB of the
frame has been latched into the SSP.

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SO LSB MSB LSB

8 bit control
SI 0 MSB LSB MSB LSB

4 to 16 bits 4 to 16 bits
output data output data

Fig 32. Microwire frame format (continuos transfers)

12.3.9 Setup and hold time requirements on CS with respect to SK in

Microwire mode
In the Microwire mode, the SSP slave samples the first bit of receive data on the rising
edge of SK after CS has gone LOW. Masters that drive a free-running SK must ensure
that the CS signal has sufficient setup and hold margins with respect to the rising edge of
SK.

Figure 33 illustrates these setup and hold time requirements. With respect to the SK rising
edge on which the first bit of receive data is to be sampled by the SSP slave, CS must
have a setup of at least two times the period of SK on which the SSP operates. With
respect to the SK rising edge previous to this edge, CS must have a hold of at least one
SK period.

tSETUP=2*tSK
t HOLD= tSK

SK
CS

Fig 33. Microwire frame format (continuos transfers, details)

12.4 Register description

The SSP contains 9 registers as shown in Table 141. All registers are byte, half word and
word accessible.

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Table 141. SSP register map

Name Description Access Reset value[1] Address
SSPCR0 Control Register 0. Selects the serial clock R/W 0x0000 0xE006 8000
rate, bus type, and data size.
SSPCR1 Control Register 1. Selects master/slave R/W 0x00 0xE006 8004
and other modes.
SSPDR Data Register. Writes fill the transmit FIFO, R/W 0x0000 0xE006 8008
and reads empty the receive FIFO.
SSPSR Status Register RO 0x03 0xE006 800C
SSPCPSR Clock Prescale Register R/W 0x00 0xE006 8010
SSPIMSC Interrupt Mask Set and Clear Register R/W 0x00 0xE006 8014
SSPRIS Raw Interrupt Status Register R/W 0x04 0xE006 8018
SSPMIS Masked Interrupt Status Register RO 0x00 0xE006 801C
SSPICR SSPICR Interrupt Clear Register WO NA 0xE006 8020

[1] Reset value reflects the data stored in used bits only. It does not include reserved bits content.

12.4.1 SSP Control Register 0 (SSPCR0 - 0xE006 8000)

This register controls the basic operation of the SSP controller.

Table 142: SSP Control Register 0 (SSPCR0 - address 0xE006 8000) bit description
Bit Symbol Value Description Reset
value
3:0 DSS Data Size Select. This field controls the number of bits 0000
transferred in each frame. Values 0000-0010 are not
supported and should not be used.
0011 4 bit transfer
0100 5 bit transfer
0101 6 bit transfer
0110 7 bit transfer
0111 8 bit transfer
1000 9 bit transfer
1001 10 bit transfer
1010 11 bit transfer
1011 12 bit transfer
1100 13 bit transfer
1101 14 bit transfer
1110 15 bit transfer
1111 16 bit transfer
5:4 FRF Frame Format. 00
00 SPI
01 SSI
10 Microwire
11 This combination is not supported and should not be used.

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Table 142: SSP Control Register 0 (SSPCR0 - address 0xE006 8000) bit description
Bit Symbol Value Description Reset
value
6 CPOL Clock Out Polarity. This bit is only used in SPI mode. 0
0 SSP controller maintains the bus clock low between frames.
1 SSP controller maintains the bus clock high between frames.
7 CPHA Clock Out Phase. This bit is only used in SPI mode. 0
0 SSP controller captures serial data on the first clock transition
of the frame, that is, the transition away from the inter-frame
state of the clock line.
1 SSP controller captures serial data on the second clock
transition of the frame, that is, the transition back to the
inter-frame state of the clock line.
15:8 SCR Serial Clock Rate. The number of prescaler-output clocks per 0x00
bit on the bus, minus one. Given that CPSDVR is the prescale
divider, and the APB clock PCLK clocks the prescaler, the bit
frequency is PCLK / (CPSDVSR * [SCR+1]).

12.4.2 SSP Control Register 1 (SSPCR1 - 0xE006 8004)

This register controls certain aspects of the operation of the SSP controller.

Table 143: SSP Control Register 1 (SSPCR1 - address 0xE006 8004) bit description
Bit Symbol Value Description Reset
value
0 LBM Loop Back Mode. 0
0 During normal operation.
1 Serial input is taken from the serial output (MOSI or MISO)
rather than the serial input pin (MISO or MOSI
respectively).
1 SSE SSP Enable. 0
0 The SSP controller is disabled.
1 The SSP controller will interact with other devices on the
serial bus. Software should write the appropriate control
information to the other SSP registers and interrupt
controller registers, before setting this bit.
2 MS Master/Slave Mode.This bit can only be written when the 0
SSE bit is 0.
The SSP controller acts as a master on the bus, driving the
0 SCLK, MOSI, and SSEL lines and receiving the MISO line.
1 The SSP controller acts as a slave on the bus, driving
MISO line and receiving SCLK, MOSI, and SSEL lines.
3 SOD Slave Output Disable. This bit is relevant only in slave 0
mode (MS = 1). If it is 1, this blocks this SSP controller
from driving the transmit data line (MISO).
7:4 - Reserved, user software should not write ones to reserved NA
bits. The value read from a reserved bit is not defined.

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12.4.3 SSP Data Register (SSPDR - 0xE006 8008)

Software can write data to be transmitted to this register, and read data that has been
received.

Table 144: SSP Data Register (SSPDR - address 0xE006 8008) bit description
Bit Symbol Description Reset value
15:0 DATA Write: software can write data to be sent in a future frame to this 0x0000
register whenever the TNF bit in the Status register is 1,
indicating that the Tx FIFO is not full. If the Tx FIFO was
previously empty and the SSP controller is not busy on the bus,
transmission of the data will begin immediately. Otherwise the
data written to this register will be sent as soon as all previous
data has been sent (and received). If the data length is less than
16 bits, software must right-justify the data written to this register.
Read: software can read data from this register whenever the
RNE bit in the Status register is 1, indicating that the Rx FIFO is
not empty. When software reads this register, the SSP controller
returns data from the least recent frame in the Rx FIFO. If the
data length is less than 16 bits, the data is right-justified in this
field with higher order bits filled with 0s.

12.4.4 SSP Status Register (SSPSR - 0xE006 800C)

This read-only register reflects the current status of the SSP controller.

Table 145: SSP Status Register (SSPSR - address 0xE006 800C) bit description
Bit Symbol Description Reset value
0 TFE Transmit FIFO Empty. This bit is 1 is the Transmit FIFO is 1
empty, 0 if not.
1 TNF Transmit FIFO Not Full. This bit is 0 if the Tx FIFO is full, 1 if not. 1
2 RNE Receive FIFO Not Empty. This bit is 0 if the Receive FIFO is 0
empty, 1 if not.
3 RFF Receive FIFO Full. This bit is 1 if the Receive FIFO is full, 0 if 0
not.
4 BSY Busy. This bit is 0 if the SSP controller is idle, or 1 if it is 0
currently sending/receiving a frame and/or the Tx FIFO is not
empty.
7:5 - Reserved, user software should not write ones to reserved bits. NA
The value read from a reserved bit is not defined.

12.4.5 SSP Clock Prescale Register (SSPCPSR - 0xE006 8010)

This register controls the factor by which the Prescaler divides the APB clock PCLK to
yield the prescaler clock that is, in turn, divided by the SCR factor in SSPCR0, to
determine the bit clock.

Table 146: SSP Clock Prescale Register (SSPCPSR - address 0xE006 8010) bit description
Bit Symbol Description Reset value
7:0 CPSDVSR This even value between 2 and 254, by which PCLK is divided 0
to yield the prescaler output clock. Bit 0 always reads as 0.

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Important: the SSPCPSR value must be properly initialized or the SSP controller will not
be able to transmit data correctly. In case of a SSP operating in the master mode, the
CPSDVSRmin = 2. While SSPCPSR and SCR do not affect operations of a SSP controller
in the slave mode, the SSP in slave mode can not receive data at clock rate higher than
PCLK/12.

12.4.6 SSP Interrupt Mask Set/Clear register (SSPIMSC - 0xE006 8014)

This register controls whether each of the four possible interrupt conditions in the SSP
controller are enabled. Note that ARM uses the word “masked” in the opposite sense from
classic computer terminology, in which “masked” meant “disabled”. ARM uses the word
“masked” to mean “enabled”. To avoid confusion we will not use the word “masked”.

Table 147: SSP Interrupt Mask Set/Clear register (SSPIMSC - address 0xE006 8014) bit
description
Bit Symbol Description Reset value
0 RORIM Software should set this bit to enable interrupt when a Receive 0
Overrun occurs, that is, when the Rx FIFO is full and another
frame is completely received. The ARM spec implies that the
preceding frame data is overwritten by the new frame data
when this occurs.
1 RTIM Software should set this bit to enable interrupt when a Receive 0
Timeout condition occurs. A Receive Timeout occurs when the
Rx FIFO is not empty, and no new data has been received, nor
has data been read from the FIFO, for 32 bit times.
2 RXIM Software should set this bit to enable interrupt when the Rx 0
FIFO is at least half full.
3 TXIM Software should set this bit to enable interrupt when the Tx 0
FIFO is at least half empty.
7:4 - Reserved, user software should not write ones to reserved NA
bits. The value read from a reserved bit is not defined.

12.4.7 SSP Raw Interrupt Status register (SSPRIS - 0xE006 8018)

This read-only register contains a 1 for each interrupt condition that is asserted,
regardless of whether or not the interrupt is enabled in the SSPIMSC.

Table 148: SSP Raw Interrupt Status register (SSPRIS - address 0xE006 8018) bit description
Bit Symbol Description Reset value
0 RORRIS This bit is 1 if another frame was completely received while the 0
RxFIFO was full. The ARM spec implies that the preceding
frame data is overwritten by the new frame data when this
occurs.
1 RTRIS This bit is 1 if when there is a Receive Timeout condition. Note 0
that a Receive Timeout can be negated if further data is
received.
2 RXRIS This bit is 1 if the Rx FIFO is at least half full. 0
3 TXRIS This bit is 1 if the Tx FIFO is at least half empty. 1
7:4 - Reserved, user software should not write ones to reserved NA
bits. The value read from a reserved bit is not defined.

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12.4.8 SSP Masked Interrupt register (SSPMIS - 0xE006 801C)

This read-only register contains a 1 for each interrupt condition that is asserted and
enabled in the SSPIMSC. When an SSP interrupt occurs, the interrupt service routine
should read this register to determine the cause(s) of the interrupt.

Table 149: SSP Masked Interrupt Status register (SSPMIS -address 0xE006 801C) bit
description
Bit Symbol Description Reset value
0 RORMIS This bit is 1 if another frame was completely received while the 0
RxFIFO was full, and this interrupt is enabled.
1 RTMIS This bit is 1 when there is a Receive Timeout condition and 0
this interrupt is enabled. Note that a Receive Timeout can be
negated if further data is received.
2 RXMIS This bit is 1 if the Rx FIFO is at least half full, and this interrupt 0
is enabled.
3 TXMIS This bit is 1 if the Tx FIFO is at least half empty, and this 0
interrupt is enabled.
7:5 - Reserved, user software should not write ones to reserved NA
bits. The value read from a reserved bit is not defined.

12.4.9 SSP Interrupt Clear Register (SSPICR - 0xE006 8020)

Software can write one or more one(s) to this write-only register, to clear the
corresponding interrupt condition(s) in the SSP controller. Note that the other two interrupt
conditions can be cleared by writing or reading the appropriate FIFO, or disabled by
clearing the corresponding bit in SSPIMSC.

Table 150: SSP interrupt Clear Register (SSPICR - address 0xE006 8020) bit description
Bit Symbol Description Reset value
0 RORIC Writing a 1 to this bit clears the “frame was received when NA
RxFIFO was full” interrupt.
1 RTIC Writing a 1 to this bit clears the Receive Timeout interrupt. NA
7:2 - Reserved, user software should not write ones to reserved NA
bits. The value read from a reserved bit is not defined.

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13.1 Features
• Standard I2C compliant bus interfaces that may be configured as Master, Slave, or
Master/Slave.
• Arbitration between simultaneously transmitting masters without corruption of serial
data on the bus.
• Programmable clock to allow adjustment of I2C transfer rates.
• Bidirectional data transfer between masters and slaves.
• Serial clock synchronization allows devices with different bit rates to communicate via
one serial bus.
• Serial clock synchronization can be used as a handshake mechanism to suspend and
resume serial transfer.
• The I2C bus may be used for test and diagnostic purposes.

13.2 Applications
Interfaces to external I2C standard parts, such as serial RAMs, LCDs, tone generators,
etc.

13.3 Description
A typical I2C bus configuration is shown in Figure 34. Depending on the state of the
direction bit (R/W), two types of data transfers are possible on the I2C bus:

• Data transfer from a master transmitter to a slave receiver. The first byte transmitted
by the master is the slave address. Next follows a number of data bytes. The slave
returns an acknowledge bit after each received byte.
• Data transfer from a slave transmitter to a master receiver. The first byte (the slave
address) is transmitted by the master. The slave then returns an acknowledge bit.
Next follows the data bytes transmitted by the slave to the master. The master returns
an acknowledge bit after all received bytes other than the last byte. At the end of the
last received byte, a “not acknowledge” is returned. The master device generates all
of the serial clock pulses and the START and STOP conditions. A transfer is ended
with a STOP condition or with a repeated START condition. Since a repeated START
condition is also the beginning of the next serial transfer, the I2C bus will not be
released.

Each of the two I2C interfaces on the LPC213x is byte oriented and has four operating
modes: master transmitter mode, master receiver mode, slave transmitter mode and
slave receiver mode.

The two I2C interfaces are identical except for the pin I/O characteristics. I2C0 complies
with entire I2C specification, supporting the ability to turn power off to the LPC213x without
causing a problem with other devices on the same I2C bus (see "The I2C-bus
specification" description under the heading "Fast-Mode", and notes for the table titled
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"Characteristics of the SDA and SCL I/O stages for F/S-mode I2C-bus devices"). This is
sometimes a useful capability, but intrinsically limits alternate uses for the same pins if the
I2C interface is not used. Seldom is this capability needed on multiple I2C interfaces
within the same microcontroller. Therefore, I2C1 and I2C2 are implemented using
standard port pins, and do not support the ability to turn power off to the LPC213x while
leaving the I2C bus functioning between other devices. This difference should be
considered during system design while assigning uses for the I2C interfaces.

pull-up pull-up
resistor resistor

SDA

I 2C bus

SCL

SDA SCL

LPC213x OTHER DEVICE WITH OTHER DEVICE WITH

I 2C INTERFACE I 2C INTERFACE

Fig 34. I2C bus configuration

13.4 Pin description

Table 151. I2C Pin Description
Pin Type Description
SDA0/1 Input/Output I2C Serial Data
SCL0/1 Input/Output I2C Serial Clock

13.5 I2C operating modes

In a given application, the I2C block may operate as a master, a slave, or both. In the slave
mode, the I2C hardware looks for its own slave address and the general call address. If
one of these addresses is detected, an interrupt is requested. If the processor wishes to
become the bus master, the hardware waits until the bus is free before the master mode is
entered so that a possible slave operation is not interrupted. If bus arbitration is lost in the
master mode, the I2C block switches to the slave mode immediately and can detect its
own slave address in the same serial transfer.

13.5.1 Master Transmitter mode

In this mode data is transmitted from master to slave. Before the master transmitter mode
can be entered, the I2CONSET register must be initialized as shown in Table 152. I2EN
must be set to 1 to enable the I2C function. If the AA bit is 0, the I2C interface will not
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acknowledge any address when another device is master of the bus, so it can not enter
slave mode. The STA, STO and SI bits must be 0. The SI Bit is cleared by writing 1 to the
SIC bit in the I2CONCLR register.

Table 152. I2CnCONSET used to configure Master mode

Bit 7 6 5 4 3 2 1 0
Symbol - I2EN STA STO SI AA - -
Value - 1 0 0 0 0 - -

The first byte transmitted contains the slave address of the receiving device (7 bits) and
the data direction bit. In this mode the data direction bit (R/W) should be 0 which means
Write. The first byte transmitted contains the slave address and Write bit. Data is
transmitted 8 bits at a time. After each byte is transmitted, an acknowledge bit is received.
START and STOP conditions are output to indicate the beginning and the end of a serial
transfer.

The I2C interface will enter master transmitter mode when software sets the STA bit. The
I2C logic will send the START condition as soon as the bus is free. After the START
condition is transmitted, the SI bit is set, and the status code in the I2STAT register is
0x08. This status code is used to vector to a state service routine which will load the slave
address and Write bit to the I2DAT register, and then clear the SI bit. SI is cleared by
writing a 1 to the SIC bit in the I2CONCLR register. The STA bit should be cleared after
writing the slave address.

When the slave address and R/W bit have been transmitted and an acknowledgment bit
has been received, the SI bit is set again, and the possible status codes now are 0x18,
0x20, or 0x38 for the master mode, or 0x68, 0x78, or 0xB0 if the slave mode was enabled
(by setting AA to 1). The appropriate actions to be taken for each of these status codes
are shown in Table 167 to Table 170.

S SLAVE ADDRESS RW A DATA A DATA A/A P

“0” - write
“1” - read data transferred
(n Bytes + Acknowledge)

A = Acknowledge (SDA low)

from Master to Slave
A = Not acknowledge (SDA high)
from Slave to Master
S = START condition
P = STOP condition

Fig 35. Format in the Master Transmitter mode

13.5.2 Master Receiver mode

In the master receiver mode, data is received from a slave transmitter. The transfer is
initiated in the same way as in the master transmitter mode. When the START condition
has been transmitted, the interrupt service routine must load the slave address and the
data direction bit to the I2C Data Register (I2DAT), and then clear the SI bit. In this case,
the data direction bit (R/W) should be 1 to indicate a read.

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When the slave address and data direction bit have been transmitted and an
acknowledge bit has been received, the SI bit is set, and the Status Register will show the
status code. For master mode, the possible status codes are 0x40, 0x48, or 0x38. For
slave mode, the possible status codes are 0x68, 0x78, or 0xB0. For details, refer to
Table 168.

S SLAVE ADDRESS R A DATA A DATA A P

“0” - write
“1” - read data transferred
(n Bytes + Acknowledge)

A = Acknowledge (SDA low)

from Master to Slave
A = Not acknowledge (SDA high)
from Slave to Master
S = START condition
P = STOP condition

Fig 36. Format of Master Receive mode

After a repeated START condition, I2C may switch to the master transmitter mode.

S SLA R A DATA A DATA A RS SLA W A DATA A P

data transferred
(n Bytes + Acknowledge)

A = Acknowledge (SDA low)

From master to slave
A = Not acknowledge (SDA high)
From slave to master
S = START condition
P = STOP condition
SLA = Slave Address

Fig 37. A master receiver switch to master Transmitter after sending repeated START

13.5.3 Slave Receiver mode

In the slave receiver mode, data bytes are received from a master transmitter. To initialize
the slave receiver mode, user write the Slave Address Register (I2ADR) and write the I2C
Control Set Register (I2CONSET) as shown in Table 153.

Table 153. I2CnCONSET used to configure Slave mode

Bit 7 6 5 4 3 2 1 0
Symbol - I2EN STA STO SI AA - -
Value - 1 0 0 0 1 - -

I2EN must be set to 1 to enable the I2C function. AA bit must be set to 1 to acknowledge
its own slave address or the general call address. The STA, STO and SI bits are set to 0.

After I2ADR and I2CONSET are initialized, the I2C interface waits until it is addressed by
its own address or general address followed by the data direction bit. If the direction bit is
0 (W), it enters slave receiver mode. If the direction bit is 1 (R), it enters slave transmitter
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mode. After the address and direction bit have been received, the SI bit is set and a valid
status code can be read from the Status Register (I2STAT). Refer to Table 169 for the
status codes and actions.

S SLAVE ADDRESS W A DATA A DATA A/A P/RS

“0” - write
“1” - read data transferred
(n Bytes + Acknowledge)

A = Acknowledge (SDA low)

from Master to Slave
A = Not acknowledge (SDA high)
from Slave to Master
S = START condition
P = STOP condition
RS = Repeated START condition

Fig 38. Format of Slave Receiver mode

13.5.4 Slave Transmitter mode

The first byte is received and handled as in the slave receiver mode. However, in this
mode, the direction bit will be 1, indicating a read operation. Serial data is transmitted via
SDA while the serial clock is input through SCL. START and STOP conditions are
recognized as the beginning and end of a serial transfer. In a given application, I2C may
operate as a master and as a slave. In the slave mode, the I2C hardware looks for its own
slave address and the general call address. If one of these addresses is detected, an
interrupt is requested. When the microcontrollers wishes to become the bus master, the
hardware waits until the bus is free before the master mode is entered so that a possible
slave action is not interrupted. If bus arbitration is lost in the master mode, the I2C
interface switches to the slave mode immediately and can detect its own slave address in
the same serial transfer.

S SLAVE ADDRESS R A DATA A DATA A P

“0” - write
“1” - read data transferred
(n Bytes + Acknowledge)

A = Acknowledge (SDA low)

from Master to Slave
A = Not acknowledge (SDA high)
from Slave to Master
S = START condition
P = STOP condition

Fig 39. Format of Slave Transmitter mode

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13.6 I2C implementation and operation

13.6.1 Input filters and output stages

Input signals are synchronized with the internal clock, and spikes shorter than three
clocks are filtered out.

The output for I2C is a special pad designed to conform to the I2C specification. The
outputs for I2C1 and I2C2 are standard port I/Os that support a subset of the full I2C
specification.

Figure 40 shows how the on-chip I2C bus interface is implemented, and the following text
describes the individual blocks.

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ADDRESS REGISTER I2ADR

INPUT COMPARATOR
FILTER

SDA

OUTPUT
SHIFT REGISTER ACK
STAGE

I2DAT
8

APB BUS
BIT COUNTER/
ARBITRATION &
SYNC LOGIC PCLK
INPUT
FILTER TIMING &
CONTROL
LOGIC
SCL
interrupt
OUTPUT SERIAL CLOCK
STAGE GENERATOR

I2CONSET
I2CONCLR CONTROL REGISTER & SCL DUTY
I2SCLH CYCLE REGISTERS
I2SCLL

status STATUS
STATUS REGISTER
bus DECODER

I2STAT
8

Fig 40. I2C Bus serial interface block diagram

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13.6.2 Address Register I2ADDR

This register may be loaded with the 7 bit slave address (7 most significant bits) to which
the I2C block will respond when programmed as a slave transmitter or receiver. The LSB
(GC) is used to enable general call address (0x00) recognition.

13.6.3 Comparator
The comparator compares the received 7 bit slave address with its own slave address (7
most significant bits in I2ADR). It also compares the first received 8 bit byte with the
general call address (0x00). If an equality is found, the appropriate status bits are set and
an interrupt is requested.

13.6.4 Shift register I2DAT

This 8 bit register contains a byte of serial data to be transmitted or a byte which has just
been received. Data in I2DAT is always shifted from right to left; the first bit to be
transmitted is the MSB (bit 7) and, after a byte has been received, the first bit of received
data is located at the MSB of I2DAT. While data is being shifted out, data on the bus is
simultaneously being shifted in; I2DAT always contains the last byte present on the bus.
Thus, in the event of lost arbitration, the transition from master transmitter to slave
receiver is made with the correct data in I2DAT.

13.6.5 Arbitration and synchronization logic

In the master transmitter mode, the arbitration logic checks that every transmitted logic 1
actually appears as a logic 1 on the I2C bus. If another device on the bus overrules a logic
1 and pulls the SDA line low, arbitration is lost, and the I2C block immediately changes
from master transmitter to slave receiver. The I2C block will continue to output clock
pulses (on SCL) until transmission of the current serial byte is complete.

Arbitration may also be lost in the master receiver mode. Loss of arbitration in this mode
can only occur while the I2C block is returning a “not acknowledge: (logic 1) to the bus.
Arbitration is lost when another device on the bus pulls this signal LOW. Since this can
occur only at the end of a serial byte, the I2C block generates no further clock pulses.
Figure 41 shows the arbitration procedure.

(1) (1) (2) (3)

SDA line

SCL line
1 2 3 4 8 9
ACK

(1) A device transmits serial data.

(2) Another device overrules a logic 1 (dotted line), transmitted by this I2C master, by pulling the SDA
line low. Arbitration is lost, and this I2C enters Slave Receiver mode.
(3) This I2C is in Slave Receiver mode but still generates clock pulses until the current byte has been
transmitted. This I2C will not generate clock pulses for the next byte. Data on SDA originates from
the new master once it has won arbitration.
Fig 41. Arbitration procedure

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The synchronization logic will synchronize the serial clock generator with the clock pulses
on the SCL line from another device. If two or more master devices generate clock pulses,
the “mark” duration is determined by the device that generates the shortest “marks,” and
the “space” duration is determined by the device that generates the longest “spaces”.
Figure 42 shows the synchronization procedure.

SDA line

(1) (3) (1)

SCL line

(2)
high low
period period

(1) Another device pulls the SCL line low before this I2C has timed a complete high time. The other
device effectively determines the (shorter) HIGH period.
(2) Another device continues to pull the SCL line low after this I2C has timed a complete low time and
released SCL. The I2C clock generator is forced to wait until SCL goes HIGH. The other device
effectively determines the (longer) LOW period.
(3) The SCL line is released , and the clock generator begins timing the HIGH time.
Fig 42. Serial clock synchronization

A slave may stretch the space duration to slow down the bus master. The space duration
may also be stretched for handshaking purposes. This can be done after each bit or after
a complete byte transfer. the I2C block will stretch the SCL space duration after a byte has
been transmitted or received and the acknowledge bit has been transferred. The serial
interrupt flag (SI) is set, and the stretching continues until the serial interrupt flag is
cleared.

13.6.6 Serial clock generator

This programmable clock pulse generator provides the SCL clock pulses when the I2C
block is in the master transmitter or master receiver mode. It is switched off when the I2C
block is in a slave mode. The I2C output clock frequency and duty cycle is programmable
via the I2C Clock Control Registers. See the description of the I2CSCLL and I2CSCLH
registers for details. The output clock pulses have a duty cycle as programmed unless the
bus is synchronizing with other SCL clock sources as described above.

13.6.7 Timing and control

The timing and control logic generates the timing and control signals for serial byte
handling. This logic block provides the shift pulses for I2DAT, enables the comparator,
generates and detects start and stop conditions, receives and transmits acknowledge bits,
controls the master and slave modes, contains interrupt request logic, and monitors the
I2C bus status.

13.6.8 Control register I2CONSET and I2CONCLR

The I2C control register contains bits used to control the following I2C block functions: start
and restart of a serial transfer, termination of a serial transfer, bit rate, address recognition,
and acknowledgment.

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The contents of the I2C control register may be read as I2CONSET. Writing to I2CONSET
will set bits in the I2C control register that correspond to ones in the value written.
Conversely, writing to I2CONCLR will clear bits in the I2C control register that correspond
to ones in the value written.

13.6.9 Status decoder and status register

The status decoder takes all of the internal status bits and compresses them into a 5 bit
code. This code is unique for each I2C bus status. The 5 bit code may be used to generate
vector addresses for fast processing of the various service routines. Each service routine
processes a particular bus status. There are 26 possible bus states if all four modes of the
I2C block are used. The 5 bit status code is latched into the five most significant bits of the
status register when the serial interrupt flag is set (by hardware) and remains stable until
the interrupt flag is cleared by software. The three least significant bits of the status
register are always zero. If the status code is used as a vector to service routines, then the
routines are displaced by eight address locations. Eight bytes of code is sufficient for most
of the service routines (see the software example in this section).

13.7 Register description

Each I2C interface contains 7 registers as shown in Table 154 below.

Table 154. Summary of I2C registers

Generic Description Access Reset I2Cn Register
Name value[1] Name & Address
I2CONSET I2C Control Set Register. When a one is written to a R/W 0x00 I2C0CONSET - 0xE001 C000
bit of this register, the corresponding bit in the I2C I2C1CONSET - 0xE005 C000
control register is set. Writing a zero has no effect on
the corresponding bit in the I2C control register.
I2STAT I2C Status Register. During I2C operation, this RO 0xF8 I2C0STAT - 0xE001 C004
register provides detailed status codes that allow I2C1STAT - 0xE005 C004
software to determine the next action needed.
I2DAT I2C Data Register. During master or slave transmit R/W 0x00 I2C0DAT - 0xE001 C008
mode, data to be transmitted is written to this register. I2C1DAT - 0xE005 C008
During master or slave receive mode, data that has
been received may be read from this register.
I2ADR I2C Slave Address Register. Contains the 7 bit slave R/W 0x00 I2C0ADR - 0xE001 C00C
address for operation of the I2C interface in slave I2C1ADR - 0xE005 C00C
mode, and is not used in master mode. The least
significant bit determines whether a slave responds to
the general call address.

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Table 154. Summary of I2C registers

Generic Description Access Reset I2Cn Register
Name value[1] Name & Address
I2SCLH SCH Duty Cycle Register High Half Word. R/W 0x04 I2C0SCLH - 0xE001 C010
Determines the high time of the I2C clock. I2C1SCLH - 0xE005 C010

I2SCLL SCL Duty Cycle Register Low Half Word. R/W 0x04 I2C0SCLL - 0xE001 C014
Determines the low time of the I2C clock. I2nSCLL I2C1SCLL - 0xE005 C014
and I2nSCLH together determine the clock frequency
generated by an I2C master and certain times used in
slave mode.
I2CONCLR I2C Control Clear Register. When a one is written to WO NA I2C0CONCLR - 0xE001 C018
a bit of this register, the corresponding bit in the I2C I2C1CONCLR - 0xE005 C018
control register is cleared. Writing a zero has no effect
on the corresponding bit in the I2C control register.

[1] Reset Value reflects the data stored in used bits only. It does not include reserved bits content.

13.7.1 I2C Control Set Register (I2C[0/1]CONSET: 0xE001 C000,

0xE005 C000)
The I2CONSET registers control setting of bits in the I2CON register that controls
operation of the I2C interface. Writing a one to a bit of this register causes the
corresponding bit in the I2C control register to be set. Writing a zero has no effect.

Table 155. I2C Control Set Register (I2C[0/1]CONSET - addresses: 0xE001 C000,
0xE005 C000) bit description
Bit Symbol Description Reset
Value
1:0 - Reserved. User software should not write ones to reserved bits. The NA
value read from a reserved bit is not defined.
2 AA Assert acknowledge flag. See the text below.
3 SI I2C interrupt flag. 0
4 STO STOP flag. See the text below. 0
5 STA START flag. See the text below. 0
6 I2EN I2C interface enable. See the text below. 0
7 - Reserved. User software should not write ones to reserved bits. The NA
value read from a reserved bit is not defined.

I2EN I2C Interface Enable. When I2EN is 1, the I2C interface is enabled. I2EN can be
cleared by writing 1 to the I2ENC bit in the I2CONCLR register. When I2EN is 0, the I2C
interface is disabled.

When I2EN is “0”, the SDA and SCL input signals are ignored, the I2C block is in the “not
addressed” slave state, and the STO bit is forced to “0”.

I2EN should not be used to temporarily release the I2C bus since, when I2EN is reset, the
I2C bus status is lost. The AA flag should be used instead.

STA is the START flag. Setting this bit causes the I2C interface to enter master mode and
transmit a START condition or transmit a repeated START condition if it is already in
master mode.

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When STA is 1 and the I2C interface is not already in master mode, it enters master mode,
checks the bus and generates a START condition if the bus is free. If the bus is not free, it
waits for a STOP condition (which will free the bus) and generates a START condition
after a delay of a half clock period of the internal clock generator. If the I2C interface is
already in master mode and data has been transmitted or received, it transmits a repeated
START condition. STA may be set at any time, including when the I2C interface is in an
addressed slave mode.

STA can be cleared by writing 1 to the STAC bit in the I2CONCLR register. When STA is
0, no START condition or repeated START condition will be generated.

If STA and STO are both set, then a STOP condition is transmitted on the I2C bus if it the
interface is in master mode, and transmits a START condition thereafter. If the I2C
interface is in slave mode, an internal STOP condition is generated, but is not transmitted
on the bus.

STO is the STOP flag. Setting this bit causes the I2C interface to transmit a STOP
condition in master mode, or recover from an error condition in slave mode. When STO is
1 in master mode, a STOP condition is transmitted on the I2C bus. When the bus detects
the STOP condition, STO is cleared automatically.

In slave mode, setting this bit can recover from an error condition. In this case, no STOP
condition is transmitted to the bus. The hardware behaves as if a STOP condition has
been received and it switches to “not addressed” slave receiver mode. The STO flag is
cleared by hardware automatically.

SI is the I2C Interrupt Flag. This bit is set when the I2C state changes. However, entering
state F8 does not set SI since there is nothing for an interrupt service routine to do in that
case.

While SI is set, the low period of the serial clock on the SCL line is stretched, and the
serial transfer is suspended. When SCL is high, it is unaffected by the state of the SI flag.
SI must be reset by software, by writing a 1 to the SIC bit in I2CONCLR register.

AA is the Assert Acknowledge Flag. When set to 1, an acknowledge (low level to SDA)
will be returned during the acknowledge clock pulse on the SCL line on the following
situations:

1. The address in the Slave Address Register has been received.

2. The general call address has been received while the general call bit (GC) in I2ADR is
set.
3. A data byte has been received while the I2C is in the master receiver mode.
4. A data byte has been received while the I2C is in the addressed slave receiver mode.

The AA bit can be cleared by writing 1 to the AAC bit in the I2CONCLR register. When AA
is 0, a not acknowledge (high level to SDA) will be returned during the acknowledge clock
pulse on the SCL line on the following situations:

1. A data byte has been received while the I2C is in the master receiver mode.
2. A data byte has been received while the I2C is in the addressed slave receiver mode.

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13.7.2 I2C Control Clear Register (I2C[0/1]CONCLR: 0xE001 C018,

0xE005 C018)
The I2CONCLR registers control clearing of bits in the I2CON register that controls
operation of the I2C interface. Writing a one to a bit of this register causes the
corresponding bit in the I2C control register to be cleared. Writing a zero has no effect.

Table 156. I2C Control Set Register (I2C[0/1]CONCLR - addresses 0xE001 C018,
0xE005 C018) bit description
Bit Symbol Description Reset
Value
1:0 - Reserved. User software should not write ones to reserved bits. The NA
value read from a reserved bit is not defined.
2 AAC Assert acknowledge Clear bit.
3 SIC I2C interrupt Clear bit. 0
4 - Reserved. User software should not write ones to reserved bits. The NA
value read from a reserved bit is not defined.
5 STAC START flag Clear bit. 0
6 I2ENC I2C interface Disable bit. 0
7 - Reserved. User software should not write ones to reserved bits. The NA
value read from a reserved bit is not defined.

AAC is the Assert Acknowledge Clear bit. Writing a 1 to this bit clears the AA bit in the
I2CONSET register. Writing 0 has no effect.

SIC is the I2C Interrupt Clear bit. Writing a 1 to this bit clears the SI bit in the I2CONSET
register. Writing 0 has no effect.

STAC is the Start flag Clear bit. Writing a 1 to this bit clears the STA bit in the I2CONSET
register. Writing 0 has no effect.

I2ENC is the I2C Interface Disable bit. Writing a 1 to this bit clears the I2EN bit in the
I2CONSET register. Writing 0 has no effect.

13.7.3 I2C Status Register (I2C[0/1]STAT - 0xE001 C004, 0xE005 C004)

Each I2C Status register reflects the condition of the corresponding I2C interface. The I2C
Status register is Read-Only.

Table 157. I2C Status Register (I2C[0/1]STAT - addresses 0xE001 C004, 0xE005 C004) bit
description
Bit Symbol Description Reset Value
2:0 - These bits are unused and are always 0. 0
7:3 Status These bits give the actual status information about the I2C interface. 0x1F

The three least significant bits are always 0. Taken as a byte, the status register contents
represent a status code. There are 26 possible status codes. When the status code is
0xF8, there is no relevant information available and the SI bit is not set. All other 25 status
codes correspond to defined I2C states. When any of these states entered, the SI bit will
be set. For a complete list of status codes, refer to tables from Table 167 to Table 170.

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13.7.4 I2C Data Register (I2C[0/1]DAT - 0xE001 C008, 0xE005 C008)

This register contains the data to be transmitted or the data just received. The CPU can
read and write to this register only while it is not in the process of shifting a byte, when the
SI bit is set. Data in I2DAT remains stable as long as the SI bit is set. Data in I2DAT is
always shifted from right to left: the first bit to be transmitted is the MSB (bit 7), and after a
byte has been received, the first bit of received data is located at the MSB of I2DAT.

Table 158. I2C Data Register (I2C[0/1]DAT - addresses 0xE001 C008, 0xE005 C008) bit
description
Bit Symbol Description Reset Value
7:0 Data This register holds data values that have been received, or are to 0
be transmitted.

13.7.5 I2C Slave Address Register (I2C[0/1]ADR - 0xE001 C00C,

0xE005 C00C)
These registers are readable and writable, and is only used when an I2C interface is set to
slave mode. In master mode, this register has no effect. The LSB of I2ADR is the general
call bit. When this bit is set, the general call address (0x00) is recognized.

Table 159. I2C Slave Address register (I2C[0/1]ADR - addresses 0xE001 C00C, 0xE005 C00C)
bit description
Bit Symbol Description Reset Value
0 GC General Call enable bit. 0
7:1 Address The I2C device address for slave mode. 0x00

13.7.6 I2C SCL High Duty Cycle Register (I2C[0/1]SCLH - 0xE001 C010,
0xE005 C010)
Table 160. I2C SCL High Duty Cycle register (I2C[0/1]SCLH - addresses 0xE001 C010,
0xE005 C010) bit description
Bit Symbol Description Reset Value
15:0 SCLH Count for SCL HIGH time period selection. 0x0004

13.7.7 I2C SCL Low Duty Cycle Register (I2C[0/1]SCLL - 0xE001 C014,
0xE005 C014)
Table 161. I2C SCL Low Duty Cycle register (I2C[0/1]SCLL - addresses 0xE001 C014,
0xE005 C014) bit description
Bit Symbol Description Reset Value
15:0 SCLL Count for SCL LOW time period selection. 0x0004

13.7.8 Selecting the appropriate I2C data rate and duty cycle
Software must set values for the registers I2SCLH and I2SCLL to select the appropriate
data rate and duty cycle. I2SCLH defines the number of PCLK cycles for the SCL high
time, I2SCLL defines the number of PCLK cycles for the SCL low time. The frequency is
determined by the following formula (fPCLK being the frequency of PCLK):

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(7)

f PCLK
I 2 C bitfrequency = --------------------------------------------------------
-
I2CSCLH + I2CSCLL

The values for I2SCLL and I2SCLH should not necessarily be the same. Software can set
different duty cycles on SCL by setting these two registers. For example, the I2C bus
specification defines the SCL low time and high time at different values for a 400 kHz I2C
rate. The value of the register must ensure that the data rate is in the I2C data rate range
of 0 through 400 kHz. Each register value must be greater than or equal to 4. Table 162
gives some examples of I2C bus rates based on PCLK frequency and I2SCLL and
I2SCLH values.

Table 162. Example I2C clock rates

I2SCLL + I2C Bit Frequency (kHz) at PCLK (MHz)
I2SCLH 1 5 10 16 20 40 60
8 125
10 100
25 40 200 400
50 20 100 200 320 400
100 10 50 100 160 200 400
160 6.25 31.25 62.5 100 125 250 375
200 5 25 50 80 100 200 300
400 2.5 12.5 25 40 50 100 150
800 1.25 6.25 12.5 20 25 50 75

13.8 Details of I2C operating modes

The four operating modes are:

• Master Transmitter
• Master Receiver
• Slave Receiver
• Slave Transmitter

Data transfers in each mode of operation are shown in Figures 43 to 47. Table 163 lists
abbreviations used in these figures when describing the I2C operating modes.

Table 163. Abbreviations used to describe an I2C operation

Abbreviation Explanation
S Start Condition
SLA 7 bit slave address
R Read bit (high level at SDA)
W Write bit (low level at SDA)
A Acknowledge bit (low level at SDA)

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Table 163. Abbreviations used to describe an I2C operation

Abbreviation Explanation
A Not acknowledge bit (high level at SDA)
Data 8 bit data byte
P Stop condition

In Figures 43 to 47, circles are used to indicate when the serial interrupt flag is set. The
numbers in the circles show the status code held in the I2STAT register. At these points, a
service routine must be executed to continue or complete the serial transfer. These
service routines are not critical since the serial transfer is suspended until the serial
interrupt flag is cleared by software.

When a serial interrupt routine is entered, the status code in I2STAT is used to branch to
the appropriate service routine. For each status code, the required software action and
details of the following serial transfer are given in tables from Table 167 to Table 171.

13.8.1 Master Transmitter mode

In the master transmitter mode, a number of data bytes are transmitted to a slave receiver
(see Figure 43). Before the master transmitter mode can be entered, I2CON must be
initialized as follows:

Table 164. I2CONSET used to initialize Master Transmitter mode

Bit 7 6 5 4 3 2 1 0
Symbol - I2EN STA STO SI AA - -
Value - 1 0 0 0 x - -

The I2C rate must also be configured in the I2SCLL and I2SCLH registers. I2EN must be
set to logic 1 to enable the I2C block. If the AA bit is reset, the I2C block will not
acknowledge its own slave address or the general call address in the event of another
device becoming master of the bus. In other words, if AA is reset, the I2C interface cannot
enter a slave mode. STA, STO, and SI must be reset.

The master transmitter mode may now be entered by setting the STA bit. The I2C logic will
now test the I2C bus and generate a start condition as soon as the bus becomes free.
When a START condition is transmitted, the serial interrupt flag (SI) is set, and the status
code in the status register (I2STAT) will be 0x08. This status code is used by the interrupt
service routine to enter the appropriate state service routine that loads I2DAT with the
slave address and the data direction bit (SLA+W). The SI bit in I2CON must then be reset
before the serial transfer can continue.

When the slave address and the direction bit have been transmitted and an
acknowledgment bit has been received, the serial interrupt flag (SI) is set again, and a
number of status codes in I2STAT are possible. There are 0x18, 0x20, or 0x38 for the
master mode and also 0x68, 0x78, or 0xB0 if the slave mode was enabled (AA = logic 1).
The appropriate action to be taken for each of these status codes is detailed in Table 167.
After a repeated start condition (state 0x10). The I2C block may switch to the master
receiver mode by loading I2DAT with SLA+R).

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13.8.2 Master Receiver mode

In the master receiver mode, a number of data bytes are received from a slave transmitter
(see Figure 44). The transfer is initialized as in the master transmitter mode. When the
start condition has been transmitted, the interrupt service routine must load I2DAT with the
7 bit slave address and the data direction bit (SLA+R). The SI bit in I2CON must then be
cleared before the serial transfer can continue.

When the slave address and the data direction bit have been transmitted and an
acknowledgment bit has been received, the serial interrupt flag (SI) is set again, and a
number of status codes in I2STAT are possible. These are 0x40, 0x48, or 0x38 for the
master mode and also 0x68, 0x78, or 0xB0 if the slave mode was enabled (AA = 1). The
appropriate action to be taken for each of these status codes is detailed in Table 168. After
a repeated start condition (state 0x10), the I2C block may switch to the master transmitter
mode by loading I2DAT with SLA+W.

13.8.3 Slave Receiver mode

In the slave receiver mode, a number of data bytes are received from a master transmitter
(see Figure 45). To initiate the slave receiver mode, I2ADR and I2CON must be loaded as
follows:

Table 165. I2C0ADR and I2C1ADR usage in Slave Receiver mode

Bit 7 6 5 4 3 2 1 0
Symbol own slave 7 bit address GC

The upper 7 bits are the address to which the I2C block will respond when addressed by a
master. If the LSB (GC) is set, the I2C block will respond to the general call address
(0x00); otherwise it ignores the general call address.

Table 166. I2C0CONSET and I2C1CONSET used to initialize Slave Receiver mode
Bit 7 6 5 4 3 2 1 0
Symbol - I2EN STA STO SI AA - -
Value - 1 0 0 0 1 - -

The I2C bus rate settings do not affect the I2C block in the slave mode. I2EN must be set
to logic 1 to enable the I2C block. The AA bit must be set to enable the I2C block to
acknowledge its own slave address or the general call address. STA, STO, and SI must
be reset.

When I2ADR and I2CON have been initialized, the I2C block waits until it is addressed by
its own slave address followed by the data direction bit which must be “0” (W) for the I2C
block to operate in the slave receiver mode. After its own slave address and the W bit
have been received, the serial interrupt flag (SI) is set and a valid status code can be read
from I2STAT. This status code is used to vector to a state service routine. The appropriate
action to be taken for each of these status codes is detailed in Table 169. The slave
receiver mode may also be entered if arbitration is lost while the I2C block is in the master
mode (see status 0x68 and 0x78).

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If the AA bit is reset during a transfer, the I2C block will return a not acknowledge (logic 1)
to SDA after the next received data byte. While AA is reset, the I2C block does not
respond to its own slave address or a general call address. However, the I2C bus is still
monitored and address recognition may be resumed at any time by setting AA. This
means that the AA bit may be used to temporarily isolate the I2C block from the I2C bus.

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successful
transmission
S SLA W A DATA A P
to a Slave
Receiver

08H 18H 28H

next transfer
started with a
S SLA W
Repeated Start
condition

Not 10H
Acknowledge
received after A P R
the Slave
address
20H
to Master
receive
Not
mode,
Acknowledge
A P entry
received after a
= MR
Data byte

30H

arbitration lost
in Slave other Master other Master
A OR A A OR A
address or continues continues
Data byte

38H 38H

arbitration lost
and other Master
A
addressed as continues
Slave
to corresponding
68H 78H B0H
states in Slave mode

from Master to Slave

from Slave to Master

any number of data bytes and their associated Acknowledge bits

DATA

this number (contained in I2STA) corresponds to a defined state of the

n
I2C bus

Fig 43. Format and States in the Master Transmitter mode

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successful
transmission to S SLA R A DATA A DATA A P
a Slave
transmitter

08H 40H 50H 58H

next transfer
started with a
S SLA R
Repeated Start
condition

10H
Not Acknowledge
received after the A P W
Slave address

48H
to Master
transmit
mode, entry
= MT

arbitration lost in
Slave address or other Master other Master
A OR A A
Acknowledge bit continues continues

38H 38H

arbitration lost
other Master
and addressed A
continues
as Slave
to corresponding
68H 78H B0H states in Slave
mode
from Master to Slave

from Slave to Master

any number of data bytes and their associated

DATA A
Acknowledge bits

this number (contained in I2STA) corresponds to a defined state of

n
the I2C bus

Fig 44. Format and States in the Master Receiver mode

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reception of the own

Slave address and one
S SLA R A DATA A DATA A P OR S
or more Data bytes all
are acknowledged

60H 80H 80H A0H

last data byte

received is Not A P OR S
acknowledged

88H
arbitration lost as
Master and addressed A
as Slave

68H

reception of the
General Call address
GENERAL CALL A DATA A DATA A P OR S
and one or more Data
bytes

70h 90h 90h A0H

last data byte is Not A P OR S

acknowledged

98h
arbitration lost as
Master and addressed
A
as Slave by General
Call

78h

from Master to Slave

from Slave to Master

DATA A any number of data bytes and their associated Acknowledge bits

this number (contained in I2STA) corresponds to a defined state of the 2IC

n
bus

Fig 45. Format and States in the Slave Receiver mode

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reception of the own

Slave address and
one or more Data S SLA R A DATA A DATA A P OR S
bytes all are
acknowledged
A8H B8H C0H

arbitration lost as
Master and A
addressed as Slave

last data byte B0H

transmitted. Switched
to Not Addressed A ALL ONES P OR S
Slave (AA bit in
I2CON = “0”)
C8H

from Master to Slave

from Slave to Master

any number of data bytes and their associated

DATA A
Acknowledge bits

this number (contained in I2STA) corresponds to a defined state of

n
the I2C bus

Fig 46. Format and States in the Slave Transmitter mode

13.8.4 Slave Transmitter mode

In the slave transmitter mode, a number of data bytes are transmitted to a master receiver
(see Figure 46). Data transfer is initialized as in the slave receiver mode. When I2ADR
and I2CON have been initialized, the I2C block waits until it is addressed by its own slave
address followed by the data direction bit which must be “1” (R) for the I2C block to
operate in the slave transmitter mode. After its own slave address and the R bit have been
received, the serial interrupt flag (SI) is set and a valid status code can be read from
I2STAT. This status code is used to vector to a state service routine, and the appropriate
action to be taken for each of these status codes is detailed in Table 170. The slave
transmitter mode may also be entered if arbitration is lost while the I2C block is in the
master mode (see state 0xB0).

If the AA bit is reset during a transfer, the I2C block will transmit the last byte of the transfer
and enter state 0xC0 or 0xC8. The I2C block is switched to the not addressed slave mode
and will ignore the master receiver if it continues the transfer. Thus the master receiver
receives all 1s as serial data. While AA is reset, the I2C block does not respond to its own
slave address or a general call address. However, the I2C bus is still monitored, and
address recognition may be resumed at any time by setting AA. This means that the AA
bit may be used to temporarily isolate the I2C block from the I2C bus.
UM10120 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved.

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Table 167. Master Transmitter mode

0x10 A repeated START Load SLA+W or X 0 0 X As above.

condition has been Load SLA+R X 0 0 X SLA+W will be transmitted; the I2C block
transmitted. will be switched to MST/REC mode.
Clear STA
0x18 SLA+W has been Load data byte or 0 0 0 X Data byte will be transmitted; ACK bit will
transmitted; ACK has be received.
been received. No I2DAT action 1 0 0 X Repeated START will be transmitted.
or
No I2DAT action 0 1 0 X STOP condition will be transmitted; STO
or flag will be reset.
No I2DAT action 1 1 0 X STOP condition followed by a START
condition will be transmitted; STO flag will
be reset.
0x20 SLA+W has been Load data byte or 0 0 0 X Data byte will be transmitted; ACK bit will
transmitted; NOT ACK be received.
has been received. No I2DAT action 1 0 0 X Repeated START will be transmitted.
or
No I2DAT action 0 1 0 X STOP condition will be transmitted; STO
or flag will be reset.
No I2DAT action 1 1 0 X STOP condition followed by a START
condition will be transmitted; STO flag will
be reset.
0x28 Data byte in I2DAT Load data byte or 0 0 0 X Data byte will be transmitted; ACK bit will
has been transmitted; be received.
ACK has been No I2DAT action 1 0 0 X Repeated START will be transmitted.
received. or
No I2DAT action 0 1 0 X STOP condition will be transmitted; STO
or flag will be reset.
No I2DAT action 1 1 0 X STOP condition followed by a START
condition will be transmitted; STO flag will
be reset.
0x30 Data byte in I2DAT Load data byte or 0 0 0 X Data byte will be transmitted; ACK bit will
has been transmitted; be received.
NOT ACK has been No I2DAT action 1 0 0 X Repeated START will be transmitted.
received. or
No I2DAT action 0 1 0 X STOP condition will be transmitted; STO
or flag will be reset.
No I2DAT action 1 1 0 X STOP condition followed by a START
condition will be transmitted; STO flag will
be reset.
0x38 Arbitration lost in No I2DAT action 0 0 0 X I2C bus will be released; not addressed
SLA+R/W or Data or slave will be entered.
bytes. No I2DAT action 1 0 0 X A START condition will be transmitted
when the bus becomes free.
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Table 168. Master Receiver mode

Status Status of the I2C bus Application software response Next action taken by I2C hardware
Code and hardware To/From I2DAT To I2CON
(I2CSTAT)
STA STO SI AA
0x08 A START condition Load SLA+R X 0 0 X SLA+R will be transmitted; ACK bit will be
has been transmitted. received.
0x10 A repeated START Load SLA+R or X 0 0 X As above.
condition has been Load SLA+W X 0 0 X SLA+W will be transmitted; the I2C block
transmitted. will be switched to MST/TRX mode.
0x38 Arbitration lost in NOT No I2DAT action 0 0 0 X I2C bus will be released; the I2C block will
ACK bit. or enter a slave mode.
No I2DAT action 1 0 0 X A START condition will be transmitted
when the bus becomes free.
0x40 SLA+R has been No I2DAT action 0 0 0 0 Data byte will be received; NOT ACK bit
transmitted; ACK has or will be returned.
been received. No I2DAT action 0 0 0 1 Data byte will be received; ACK bit will be
returned.
0x48 SLA+R has been No I2DAT action 1 0 0 X Repeated START condition will be
transmitted; NOT ACK or transmitted.
has been received. No I2DAT action 0 1 0 X STOP condition will be transmitted; STO
or flag will be reset.
No I2DAT action 1 1 0 X STOP condition followed by a START
condition will be transmitted; STO flag will
be reset.
0x50 Data byte has been Read data byte or 0 0 0 0 Data byte will be received; NOT ACK bit
received; ACK has will be returned.
been returned. Read data byte 0 0 0 1 Data byte will be received; ACK bit will be
returned.
0x58 Data byte has been Read data byte or 1 0 0 X Repeated START condition will be
received; NOT ACK transmitted.
has been returned. Read data byte or 0 1 0 X STOP condition will be transmitted; STO
flag will be reset.
Read data byte 1 1 0 X STOP condition followed by a START
condition will be transmitted; STO flag will
be reset.

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Table 169. Slave Receiver Mode

Status Status of the I2C bus Application software response Next action taken by I2C hardware
Code and hardware To/From I2DAT To I2CON
(I2CSTAT)
STA STO SI AA
0x60 Own SLA+W has No I2DAT action X 0 0 0 Data byte will be received and NOT ACK
been received; ACK or will be returned.
has been returned. No I2DAT action X 0 0 1 Data byte will be received and ACK will
be returned.
0x68 Arbitration lost in No I2DAT action X 0 0 0 Data byte will be received and NOT ACK
SLA+R/W as master; or will be returned.
Own SLA+W has No I2DAT action X 0 0 1 Data byte will be received and ACK will
been received, ACK be returned.
returned.
0x70 General call address No I2DAT action X 0 0 0 Data byte will be received and NOT ACK
(0x00) has been or will be returned.
received; ACK has No I2DAT action X 0 0 1 Data byte will be received and ACK will
been returned. be returned.
0x78 Arbitration lost in No I2DAT action X 0 0 0 Data byte will be received and NOT ACK
SLA+R/W as master; or will be returned.
General call address No I2DAT action X 0 0 1 Data byte will be received and ACK will
has been received, be returned.
ACK has been
returned.
0x80 Previously addressed Read data byte or X 0 0 0 Data byte will be received and NOT ACK
with own SLV will be returned.
address; DATA has Read data byte X 0 0 1 Data byte will be received and ACK will
been received; ACK be returned.
has been returned.
0x88 Previously addressed Read data byte or 0 0 0 0 Switched to not addressed SLV mode; no
with own SLA; DATA recognition of own SLA or General call
byte has been address.
received; NOT ACK Read data byte or 0 0 0 1 Switched to not addressed SLV mode;
has been returned. Own SLA will be recognized; General call
address will be recognized if
I2ADR[0] = logic 1.
Read data byte or 1 0 0 0 Switched to not addressed SLV mode; no
recognition of own SLA or General call
address. A START condition will be
transmitted when the bus becomes free.
Read data byte 1 0 0 1 Switched to not addressed SLV mode;
Own SLA will be recognized; General call
address will be recognized if
I2ADR[0] = logic 1. A START condition
will be transmitted when the bus becomes
free.
0x90 Previously addressed Read data byte or X 0 0 0 Data byte will be received and NOT ACK
with General Call; will be returned.
DATA byte has been Read data byte X 0 0 1 Data byte will be received and ACK will
received; ACK has be returned.
been returned.

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Table 169. Slave Receiver Mode

Status Status of the I2C bus Application software response Next action taken by I2C hardware
Code and hardware To/From I2DAT To I2CON
(I2CSTAT)
STA STO SI AA
0x98 Previously addressed Read data byte or 0 0 0 0 Switched to not addressed SLV mode; no
with General Call; recognition of own SLA or General call
DATA byte has been address.
received; NOT ACK Read data byte or 0 0 0 1 Switched to not addressed SLV mode;
has been returned. Own SLA will be recognized; General call
address will be recognized if
I2ADR[0] = logic 1.
Read data byte or 1 0 0 0 Switched to not addressed SLV mode; no
recognition of own SLA or General call
address. A START condition will be
transmitted when the bus becomes free.
Read data byte 1 0 0 1 Switched to not addressed SLV mode;
Own SLA will be recognized; General call
address will be recognized if
I2ADR[0] = logic 1. A START condition
will be transmitted when the bus becomes
free.
0xA0 A STOP condition or No STDAT action 0 0 0 0 Switched to not addressed SLV mode; no
repeated START or recognition of own SLA or General call
condition has been address.
received while still No STDAT action 0 0 0 1 Switched to not addressed SLV mode;
addressed as or Own SLA will be recognized; General call
SLV/REC or address will be recognized if
SLV/TRX. I2ADR[0] = logic 1.
No STDAT action 1 0 0 0 Switched to not addressed SLV mode; no
or recognition of own SLA or General call
address. A START condition will be
transmitted when the bus becomes free.
No STDAT action 1 0 0 1 Switched to not addressed SLV mode;
Own SLA will be recognized; General call
address will be recognized if
I2ADR[0] = logic 1. A START condition
will be transmitted when the bus becomes
free.

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Table 170. Tad_105: Slave Transmitter mode

Status Status of the I2C bus Application software response Next action taken by I2C hardware
Code and hardware To/From I2DAT To I2CON
(I2CSTAT)
STA STO SI AA
0xA8 Own SLA+R has been Load data byte or X 0 0 0 Last data byte will be transmitted and
received; ACK has ACK bit will be received.
been returned. Load data byte X 0 0 1 Data byte will be transmitted; ACK will be
received.
0xB0 Arbitration lost in Load data byte or X 0 0 0 Last data byte will be transmitted and
SLA+R/W as master; ACK bit will be received.
Own SLA+R has been Load data byte X 0 0 1 Data byte will be transmitted; ACK bit will
received, ACK has be received.
been returned.
0xB8 Data byte in I2DAT Load data byte or X 0 0 0 Last data byte will be transmitted and
has been transmitted; ACK bit will be received.
ACK has been Load data byte X 0 0 1 Data byte will be transmitted; ACK bit will
received. be received.
0xC0 Data byte in I2DAT No I2DAT action 0 0 0 0 Switched to not addressed SLV mode; no
has been transmitted; or recognition of own SLA or General call
NOT ACK has been address.
received. No I2DAT action 0 0 0 1 Switched to not addressed SLV mode;
or Own SLA will be recognized; General call
address will be recognized if
I2ADR[0] = logic 1.
No I2DAT action 1 0 0 0 Switched to not addressed SLV mode; no
or recognition of own SLA or General call
address. A START condition will be
transmitted when the bus becomes free.
No I2DAT action 1 0 0 1 Switched to not addressed SLV mode;
Own SLA will be recognized; General call
address will be recognized if
I2ADR[0] = logic 1. A START condition
will be transmitted when the bus becomes
free.
0xC8 Last data byte in No I2DAT action 0 0 0 0 Switched to not addressed SLV mode; no
I2DAT has been or recognition of own SLA or General call
transmitted (AA = 0); address.
ACK has been No I2DAT action 0 0 0 1 Switched to not addressed SLV mode;
received. or Own SLA will be recognized; General call
address will be recognized if
I2ADR[0] = logic 1.
No I2DAT action 1 0 0 0 Switched to not addressed SLV mode; no
or recognition of own SLA or General call
address. A START condition will be
transmitted when the bus becomes free.
No I2DAT action 1 0 0 1 Switched to not addressed SLV mode;
Own SLA will be recognized; General call
address will be recognized if
I2ADR.0 = logic 1. A START condition will
be transmitted when the bus becomes
free.

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13.8.5 Miscellaneous states

There are two I2STAT codes that do not correspond to a defined I2C hardware state (see
Table 171). These are discussed below.

13.8.5.1 I2STAT = 0xF8

This status code indicates that no relevant information is available because the serial
interrupt flag, SI, is not yet set. This occurs between other states and when the I2C block
is not involved in a serial transfer.

13.8.5.2 I2STAT = 0x00

This status code indicates that a bus error has occurred during an I2C serial transfer. A
bus error is caused when a START or STOP condition occurs at an illegal position in the
format frame. Examples of such illegal positions are during the serial transfer of an
address byte, a data byte, or an acknowledge bit. A bus error may also be caused when
external interference disturbs the internal I2C block signals. When a bus error occurs, SI is
set. To recover from a bus error, the STO flag must be set and SI must be cleared. This
causes the I2C block to enter the “not addressed” slave mode (a defined state) and to
clear the STO flag (no other bits in I2CON are affected). The SDA and SCL lines are
released (a STOP condition is not transmitted).

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Table 171. Miscellaneous states

Status Status of the I2C bus Application software response Next action taken by I2C hardware
Code and hardware To/From I2DAT To I2CON
(I2CSTAT)
STA STO SI AA
0xF8 No relevant state No I2DAT action No I2CON action Wait or proceed current transfer.
information available;
SI = 0.
0x00 Bus error during MST No I2DAT action 0 1 0 X Only the internal hardware is affected in
or selected slave the MST or addressed SLV modes. In all
modes, due to an cases, the bus is released and the I2C
illegal START or block is switched to the not addressed
STOP condition. State SLV mode. STO is reset.
0x00 can also occur
when interference
causes the I2C block
to enter an undefined
state.

13.8.6 Some special cases

The I2C hardware has facilities to handle the following special cases that may occur
during a serial transfer:

13.8.7 Simultaneous repeated START conditions from two masters

A repeated START condition may be generated in the master transmitter or master
receiver modes. A special case occurs if another master simultaneously generates a
repeated START condition (see Figure 47). Until this occurs, arbitration is not lost by
either master since they were both transmitting the same data.

If the I2C hardware detects a repeated START condition on the I2C bus before generating
a repeated START condition itself, it will release the bus, and no interrupt request is
generated. If another master frees the bus by generating a STOP condition, the I2C block
will transmit a normal START condition (state 0x08), and a retry of the total serial data
transfer can commence.

13.8.8 Data transfer after loss of arbitration

Arbitration may be lost in the master transmitter and master receiver modes (see
Figure 41). Loss of arbitration is indicated by the following states in I2STAT; 0x38, 0x68,
0x78, and 0xB0 (see Figure 43 and Figure 44).

If the STA flag in I2CON is set by the routines which service these states, then, if the bus
is free again, a START condition (state 0x08) is transmitted without intervention by the
CPU, and a retry of the total serial transfer can commence.

13.8.9 Forced access to the I2C bus

In some applications, it may be possible for an uncontrolled source to cause a bus
hang-up. In such situations, the problem may be caused by interference, temporary
interruption of the bus or a temporary short-circuit between SDA and SCL.

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If an uncontrolled source generates a superfluous START or masks a STOP condition,

then the I2C bus stays busy indefinitely. If the STA flag is set and bus access is not
obtained within a reasonable amount of time, then a forced access to the I2C bus is
possible. This is achieved by setting the STO flag while the STA flag is still set. No STOP
condition is transmitted. The I2C hardware behaves as if a STOP condition was received
and is able to transmit a START condition. The STO flag is cleared by hardware (see
Figure 48).

13.8.10 I2C Bus obstructed by a Low level on SCL or SDA

An I2C bus hang-up occurs if SDA or SCL is pulled LOW by an uncontrolled source. If the
SCL line is obstructed (pulled LOW) by a device on the bus, no further serial transfer is
possible, and the I2C hardware cannot resolve this type of problem. When this occurs, the
problem must be resolved by the device that is pulling the SCL bus line LOW.

If the SDA line is obstructed by another device on the bus (e.g., a slave device out of bit
synchronization), the problem can be solved by transmitting additional clock pulses on the
SCL line (see Figure 49). The I2C hardware transmits additional clock pulses when the
STA flag is set, but no START condition can be generated because the SDA line is pulled
LOW while the I2C bus is considered free. The I2C hardware attempts to generate a
START condition after every two additional clock pulses on the SCL line. When the SDA
line is eventually released, a normal START condition is transmitted, state 0x08 is
entered, and the serial transfer continues.

If a forced bus access occurs or a repeated START condition is transmitted while SDA is
obstructed (pulled LOW), the I2C hardware performs the same action as described above.
In each case, state 0x08 is entered after a successful START condition is transmitted and
normal serial transfer continues. Note that the CPU is not involved in solving these bus
hang-up problems.

13.8.11 Bus error

A bus error occurs when a START or STOP condition is present at an illegal position in the
format frame. Examples of illegal positions are during the serial transfer of an address
byte, a data bit, or an acknowledge bit.

The I2C hardware only reacts to a bus error when it is involved in a serial transfer either as
a master or an addressed slave. When a bus error is detected, the I2C block immediately
switches to the not addressed slave mode, releases the SDA and SCL lines, sets the
interrupt flag, and loads the status register with 0x00. This status code may be used to
vector to a state service routine which either attempts the aborted serial transfer again or
simply recovers from the error condition as shown in Table 171.

OTHER MASTER
S SLA W A DATA A S P S SLA
CONTINUES

08H 18H 28H 08H

other Master sends

retry
repeated START earlier

Fig 47. Simultaneous repeated START conditions from 2 masters

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time limit

STA flag

STO flag

SDA line

SCL line

start
condition

Fig 48. Forced access to a busy I2C bus

STA flag
(2) (3)

(1) (1)
SDA line

SCL line

start
condition

(1) Unsuccessful attempt to send a start condition.

(2) SDA line is released.
(3) Successful attempt to send a start condition. State 08H is entered.
Fig 49. Recovering from a bus obstruction caused by a low level on SDA

13.8.12 I2C State service routines

This section provides examples of operations that must be performed by various I2C state
service routines. This includes:

• Initialization of the I2C block after a Reset.

• I2C Interrupt Service.
• The 26 state service routines providing support for all four I2C operating modes.

13.8.12.1 Initialization
In the initialization example, the I2C block is enabled for both master and slave modes.
For each mode, a buffer is used for transmission and reception. The initialization routine
performs the following functions:

• I2ADR is loaded with the part’s own slave address and the general call bit (GC).
• The I2C interrupt enable and interrupt priority bits are set.
• The slave mode is enabled by simultaneously setting the I2EN and AA bits in I2CON
and the serial clock frequency (for master modes) is defined by loading CR0 and CR1
in I2CON. The master routines must be started in the main program.

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The I2C hardware now begins checking the I2C bus for its own slave address and general
call. If the general call or the own slave address is detected, an interrupt is requested and
I2STAT is loaded with the appropriate state information.

13.8.12.2 I2C interrupt service

When the I2C interrupt is entered, I2STAT contains a status code which identifies one of
the 26 state services to be executed.

13.8.12.3 The state service routines

Each state routine is part of the I2C interrupt routine and handles one of the 26 states.

13.8.12.4 Adapting state services to an application

The state service examples show the typical actions that must be performed in response
to the 26 I2C state codes. If one or more of the four I2C operating modes are not used, the
associated state services can be omitted, as long as care is taken that the those states
can never occur.

In an application, it may be desirable to implement some kind of time-out during I2C

operations, in order to trap an inoperative bus or a lost service routine.

13.9 Software example

13.9.1 Initialization routine

Example to initialize I2C Interface as a Slave and/or Master.

1. Load I2ADR with own Slave Address, enable general call recognition if needed.
2. Enable I2C interrupt.
3. Write 0x44 to I2CONSET to set the I2EN and AA bits, enabling Slave functions. For
Master only functions, write 0x40 to I2CONSET.

13.9.2 Start master transmit function

Begin a Master Transmit operation by setting up the buffer, pointer, and data count, then
initiating a Start.

1. Initialize Master data counter.

2. Set up the Slave Address to which data will be transmitted, and add the Write bit.
3. Write 0x20 to I2CONSET to set the STA bit.
4. Set up data to be transmitted in Master Transmit buffer.
5. Initialize the Master data counter to match the length of the message being sent.
6. Exit

13.9.3 Start master receive function

Begin a Master Receive operation by setting up the buffer, pointer, and data count, then
initiating a Start.

1. Initialize Master data counter.

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2. Set up the Slave Address to which data will be transmitted, and add the Read bit.
3. Write 0x20 to I2CONSET to set the STA bit.
4. Set up the Master Receive buffer.
5. Initialize the Master data counter to match the length of the message to be received.
6. Exit

13.9.4 I2C interrupt routine

Determine the I2C state and which state routine will be used to handle it.

1. Read the I2C status from I2STA.

2. Use the status value to branch to one of 26 possible state routines.

13.9.5 Non mode specific states

13.9.5.1 State: 0x00

Bus Error. Enter not addressed Slave mode and release bus.

1. Write 0x14 to I2CONSET to set the STO and AA bits.

2. Write 0x08 to I2CONCLR to clear the SI flag.
3. Exit

13.9.6 Master states

State 08 and State 10 are for both Master Transmit and Master Receive modes. The R/W
bit decides whether the next state is within Master Transmit mode or Master Receive
mode.

13.9.6.1 State: 0x08

A Start condition has been transmitted. The Slave Address + R/W bit will be transmitted,
an ACK bit will be received.

1. Write Slave Address with R/W bit to I2DAT.

2. Write 0x04 to I2CONSET to set the AA bit.
3. Write 0x08 to I2CONCLR to clear the SI flag.
4. Set up Master Transmit mode data buffer.
5. Set up Master Receive mode data buffer.
6. Initialize Master data counter.
7. Exit

13.9.6.2 State: 0x10

A repeated Start condition has been transmitted. The Slave Address + R/W bit will be
transmitted, an ACK bit will be received.

1. Write Slave Address with R/W bit to I2DAT.

2. Write 0x04 to I2CONSET to set the AA bit.
3. Write 0x08 to I2CONCLR to clear the SI flag.
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4. Set up Master Transmit mode data buffer.

5. Set up Master Receive mode data buffer.
6. Initialize Master data counter.
7. Exit

13.9.7 Master Transmitter states

13.9.7.1 State: 0x18

Previous state was State 8 or State 10, Slave Address + Write has been transmitted, ACK
has been received. The first data byte will be transmitted, an ACK bit will be received.

1. Load I2DAT with first data byte from Master Transmit buffer.
2. Write 0x04 to I2CONSET to set the AA bit.
3. Write 0x08 to I2CONCLR to clear the SI flag.
4. Increment Master Transmit buffer pointer.
5. Exit

13.9.7.2 State: 0x20

Slave Address + Write has been transmitted, NOT ACK has been received. A Stop
condition will be transmitted.

1. Write 0x14 to I2CONSET to set the STO and AA bits.

2. Write 0x08 to I2CONCLR to clear the SI flag.
3. Exit

13.9.7.3 State: 0x28

Data has been transmitted, ACK has been received. If the transmitted data was the last
data byte then transmit a Stop condition, otherwise transmit the next data byte.

1. Decrement the Master data counter, skip to step 5 if not the last data byte.
2. Write 0x14 to I2CONSET to set the STO and AA bits.
3. Write 0x08 to I2CONCLR to clear the SI flag.
4. Exit
5. Load I2DAT with next data byte from Master Transmit buffer.
6. Write 0x04 to I2CONSET to set the AA bit.
7. Write 0x08 to I2CONCLR to clear the SI flag.
8. Increment Master Transmit buffer pointer
9. Exit

13.9.7.4 State: 0x30

Data has been transmitted, NOT ACK received. A Stop condition will be transmitted.

1. Write 0x14 to I2CONSET to set the STO and AA bits.

2. Write 0x08 to I2CONCLR to clear the SI flag.
3. Exit
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13.9.7.5 State: 0x38

Arbitration has been lost during Slave Address + Write or data. The bus has been
released and not addressed Slave mode is entered. A new Start condition will be
transmitted when the bus is free again.

1. Write 0x24 to I2CONSET to set the STA and AA bits.

2. Write 0x08 to I2CONCLR to clear the SI flag.
3. Exit

13.9.8 Master Receive states

13.9.8.1 State: 0x40

Previous state was State 08 or State 10. Slave Address + Read has been transmitted,
ACK has been received. Data will be

received and ACK returned.

1. Write 0x04 to I2CONSET to set the AA bit.

2. Write 0x08 to I2CONCLR to clear the SI flag.
3. Exit

13.9.8.2 State: 0x48

Slave Address + Read has been transmitted, NOT ACK has been received. A Stop
condition will be transmitted.

1. Write 0x14 to I2CONSET to set the STO and AA bits.

2. Write 0x08 to I2CONCLR to clear the SI flag.
3. Exit

13.9.8.3 State: 0x50

Data has been received, ACK has been returned. Data will be read from I2DAT. Additional
data will be received. If this is the last data byte then NOT ACK will be returned, otherwise
ACK will be returned.

1. Read data byte from I2DAT into Master Receive buffer.

2. Decrement the Master data counter, skip to step 5 if not the last data byte.
3. Write 0x0C to I2CONCLR to clear the SI flag and the AA bit.
4. Exit
5. Write 0x04 to I2CONSET to set the AA bit.
6. Write 0x08 to I2CONCLR to clear the SI flag.
7. Increment Master Receive buffer pointer
8. Exit

13.9.8.4 State: 0x58

Data has been received, NOT ACK has been returned. Data will be read from I2DAT. A
Stop condition will be transmitted.

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1. Read data byte from I2DAT into Master Receive buffer.

2. Write 0x14 to I2CONSET to set the STO and AA bits.
3. Write 0x08 to I2CONCLR to clear the SI flag.
4. Exit

13.9.9 Slave Receiver states

13.9.9.1 State: 0x60

Own Slave Address + Write has been received, ACK has been returned. Data will be
received and ACK returned.

1. Write 0x04 to I2CONSET to set the AA bit.

2. Write 0x08 to I2CONCLR to clear the SI flag.
3. Set up Slave Receive mode data buffer.
4. Initialize Slave data counter.
5. Exit

13.9.9.2 State: 0x68

Arbitration has been lost in Slave Address and R/W bit as bus Master. Own Slave Address
+ Write has been received, ACK has been returned. Data will be received and ACK will be
returned. STA is set to restart Master mode after the bus is free again.

1. Write 0x24 to I2CONSET to set the STA and AA bits.

2. Write 0x08 to I2CONCLR to clear the SI flag.
3. Set up Slave Receive mode data buffer.
4. Initialize Slave data counter.
5. Exit.

13.9.9.3 State: 0x70

General call has been received, ACK has been returned. Data will be received and ACK
returned.

1. Write 0x04 to I2CONSET to set the AA bit.

2. Write 0x08 to I2CONCLR to clear the SI flag.
3. Set up Slave Receive mode data buffer.
4. Initialize Slave data counter.
5. Exit

13.9.9.4 State: 0x78

Arbitration has been lost in Slave Address + R/W bit as bus Master. General call has been
received and ACK has been returned. Data will be received and ACK returned. STA is set
to restart Master mode after the bus is free again.

1. Write 0x24 to I2CONSET to set the STA and AA bits.

2. Write 0x08 to I2CONCLR to clear the SI flag.

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3. Set up Slave Receive mode data buffer.

4. Initialize Slave data counter.
5. Exit

13.9.9.5 State: 0x80

Previously addressed with own Slave Address. Data has been received and ACK has
been returned. Additional data will be read.

1. Read data byte from I2DAT into the Slave Receive buffer.
2. Decrement the Slave data counter, skip to step 5 if not the last data byte.
3. Write 0x0C to I2CONCLR to clear the SI flag and the AA bit.
4. Exit.
5. Write 0x04 to I2CONSET to set the AA bit.
6. Write 0x08 to I2CONCLR to clear the SI flag.
7. Increment Slave Receive buffer pointer.
8. Exit

13.9.9.6 State: 0x88

Previously addressed with own Slave Address. Data has been received and NOT ACK
has been returned. Received data will not be saved. Not addressed Slave mode is
entered.

1. Write 0x04 to I2CONSET to set the AA bit.

2. Write 0x08 to I2CONCLR to clear the SI flag.
3. Exit

13.9.9.7 State: 0x90

Previously addressed with general call. Data has been received, ACK has been returned.
Received data will be saved. Only the first data byte will be received with ACK. Additional
data will be received with NOT ACK.

1. Read data byte from I2DAT into the Slave Receive buffer.
2. Write 0x0C to I2CONCLR to clear the SI flag and the AA bit.
3. Exit

13.9.9.8 State: 0x98

Previously addressed with general call. Data has been received, NOT ACK has been
returned. Received data will not be saved. Not addressed Slave mode is entered.

1. Write 0x04 to I2CONSET to set the AA bit.

2. Write 0x08 to I2CONCLR to clear the SI flag.
3. Exit

13.9.9.9 State: 0xA0

A Stop condition or repeated Start has been received, while still addressed as a Slave.
Data will not be saved. Not addressed Slave mode is entered.

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1. Write 0x04 to I2CONSET to set the AA bit.

2. Write 0x08 to I2CONCLR to clear the SI flag.
3. Exit

13.9.10 Slave Transmitter States

13.9.10.1 State: 0xA8

Own Slave Address + Read has been received, ACK has been returned. Data will be
transmitted, ACK bit will be received.

1. Load I2DAT from Slave Transmit buffer with first data byte.
2. Write 0x04 to I2CONSET to set the AA bit.
3. Write 0x08 to I2CONCLR to clear the SI flag.
4. Set up Slave Transmit mode data buffer.
5. Increment Slave Transmit buffer pointer.
6. Exit

13.9.10.2 State: 0xB0

Arbitration lost in Slave Address and R/W bit as bus Master. Own Slave Address + Read
has been received, ACK has been returned. Data will be transmitted, ACK bit will be
received. STA is set to restart Master mode after the bus is free again.

1. Load I2DAT from Slave Transmit buffer with first data byte.
2. Write 0x24 to I2CONSET to set the STA and AA bits.
3. Write 0x08 to I2CONCLR to clear the SI flag.
4. Set up Slave Transmit mode data buffer.
5. Increment Slave Transmit buffer pointer.
6. Exit

13.9.10.3 State: 0xB8

Data has been transmitted, ACK has been received. Data will be transmitted, ACK bit will
be received.

1. Load I2DAT from Slave Transmit buffer with data byte.

2. Write 0x04 to I2CONSET to set the AA bit.
3. Write 0x08 to I2CONCLR to clear the SI flag.
4. Increment Slave Transmit buffer pointer.
5. Exit

13.9.10.4 State: 0xC0

Data has been transmitted, NOT ACK has been received. Not addressed Slave mode is
entered.

1. Write 0x04 to I2CONSET to set the AA bit.

2. Write 0x08 to I2CONCLR to clear the SI flag.

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3. Exit

13.9.10.5 State: 0xC8

The last data byte has been transmitted, ACK has been received. Not addressed Slave
mode is entered.

1. Write 0x04 to I2CONSET to set the AA bit.

2. Write 0x08 to I2CONCLR to clear the SI flag.
3. Exit

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UM10120
Chapter 14: LPC213x Timer
Rev. 3 — 4 October 2010 User manual

14.1 Features
• A 32-bit Timer/Counter with a programmable 32-bit Prescaler.
• Counter or Timer operation.
• External Event Counting capabilities (LPC213x/01 devices only).
• Up to four 32-bit capture channels per timer, that can take a snapshot of the timer
value when an input signal transitions. A capture event may also optionally generate
an interrupt.
• Four 32-bit match registers that allow:
– Continuous operation with optional interrupt generation on match.
– Stop timer on match with optional interrupt generation.
– Reset timer on match with optional interrupt generation.
• Up to four external outputs corresponding to match registers, with the following
capabilities:
– Set low on match.
– Set high on match.
– Toggle on match.
– Do nothing on match.

14.2 Applications
• Interval Timer for counting internal events.
• Pulse Width Demodulator via Capture inputs.
• Free running timer.
• External Event/Clock counter.

14.3 Description
The Timer/Counter is designed to count cycles of the peripheral clock (PCLK) or an
externally-supplied clock, and can optionally generate interrupts or perform other actions
at specified timer values, based on four match registers. It also includes four capture
inputs to trap the timer value when an input signal transitions, optionally generating an
interrupt.

14.4 Pin description

Table 172 gives a brief summary of each of the Timer/Counter related pins.

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Table 172. Timer/Counter pin description

Pin Type Description
CAP0.3..0 Input Capture Signals- A transition on a capture pin can be configured to
CAP1.3..0 load one of the Capture Registers with the value in the Timer Counter
and optionally generate an interrupt. Capture functionality can be
selected from a number of pins. When more than one pin is selected
for a Capture input on a single TIMER0/1 channel, the pin with the
lowest Port number is used. If for example pins 30 (P0.6) and 46
(P0.16) are selected for CAP0.2, only pin 30 will be used by TIMER0 to
perform CAP0.2 function.
Here is the list of all CAPTURE signals, together with pins on where
they can be selected:
• CAP0.0 (3 pins) : P0.2, P0.22 and P0.30
• CAP0.1 (2 pins) : P0.4 and P0.27
• CAP0.2 (3 pin) : P0.6, P0.16 and P0.28
• CAP0.3 (1 pin) : P0.29
• CAP1.0 (1 pin) : P0.10
• CAP1.1 (1 pin) : P0.11
• CAP1.2 (2 pins) : P0.17 and P0.19
• CAP1.3 (2 pins) : P0.18 and P0.21
Timer/Counter block can select a capture signal as a clock source
instead of the PCLK derived clock. For more details see Section 14.5.3
“Count Control Register (CTCR, TIMER0: T0CTCR - 0xE000 4070 and
TIMER1: T1CTCR - 0xE000 8070)” on page 195.
MAT0.3..0 Output External Match Output 0/1- When a match register 0/1 (MR3:0) equals
MAT1.3..0 the timer counter (TC) this output can either toggle, go low, go high, or
do nothing. The External Match Register (EMR) controls the
functionality of this output. Match Output functionality can be selected
on a number of pins in parallel. It is also possible for example, to have
2 pins selected at the same time so that they provide MAT1.3 function
in parallel.
Here is the list of all MATCH signals, together with pins on where they
can be selected:
• MAT0.0 (2 pins) : P0.3 and P0.22
• MAT0.1 (2 pins) : P0.5 and P0.27
• MAT0.2 (2 pin) : P0.16 and P0.28
• MAT0.3 (1 pin) : P0.29
• MAT1.0 (1 pin) : P0.12
• MAT1.1 (1 pin) : P0.13
• MAT1.2 (2 pins) : P0.17 and P0.19
• MAT1.3 (2 pins) : P0.18 and P0.20

14.5 Register description

Each Timer/Counter contains the registers shown in Table 173. More detailed descriptions
follow.

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Table 173. TIMER/COUNTER0 and TIMER/COUNTER1 register map

Generic Description Access Reset TIMER/ TIMER/
Name value[1] COUNTER0 COUNTER1
Address & Name Address & Name
IR Interrupt Register. The IR can be written to clear R/W 0 0xE000 4000 0xE000 8000
interrupts. The IR can be read to identify which of T0IR T1IR
eight possible interrupt sources are pending.
TCR Timer Control Register. The TCR is used to control R/W 0 0xE000 4004 0xE000 8004
the Timer Counter functions. The Timer Counter can T0TCR T1TCR
be disabled or reset through the TCR.
TC Timer Counter. The 32-bit TC is incremented every R/W 0 0xE000 4008 0xE000 8008
PR+1 cycles of PCLK. The TC is controlled through T0TC T1TC
the TCR.
PR Prescale Register. The Prescale Counter (below) is R/W 0 0xE000 400C 0xE000 800C
equal to this value, the next clock increments the TC T0PR T1PR
and clears the PC.
PC Prescale Counter. The 32-bit PC is a counter which R/W 0 0xE000 4010 0xE000 8010
is incremented to the value stored in PR. When the T0PC T1PC
value in PR is reached, the TC is incremented and
the PC is cleared. The PC is observable and
controllable through the bus interface.
MCR Match Control Register. The MCR is used to control R/W 0 0xE0004014 0xE000 8014
if an interrupt is generated and if the TC is reset T0MCR T1MCR
when a Match occurs.
MR0 Match Register 0. MR0 can be enabled through the R/W 0 0xE000 4018 0xE000 8018
MCR to reset the TC, stop both the TC and PC, T0MR0 T1MR0
and/or generate an interrupt every time MR0
matches the TC.
MR1 Match Register 1. See MR0 description. R/W 0 0xE000 401C 0xE000 801C
T0MR1 T1MR1
MR2 Match Register 2. See MR0 description. R/W 0 0xE000 4020 0xE000 8020
T0MR2 T1MR2
MR3 Match Register 3. See MR0 description. R/W 0 0xE000 4024 0xE000 8024
T0MR3 T1MR3
CCR Capture Control Register. The CCR controls which R/W 0 0xE000 4028 0xE000 8028
edges of the capture inputs are used to load the T0CCR T1CCR
Capture Registers and whether or not an interrupt is
generated when a capture takes place.
CR0 Capture Register 0. CR0 is loaded with the value of RO 0 0xE000 402C 0xE000 802C
TC when there is an event on the CAPn.0(CAP0.0 or T0CR0 T1CR0
CAP1.0 respectively) input.
CR1 Capture Register 1. See CR0 description. RO 0 0xE000 4030 0xE000 8030
T0CR1 T1CR1
CR2 Capture Register 2. See CR0 description. RO 0 0xE000 4034 0xE000 8034
T0CR2 T1CR2

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Table 173. TIMER/COUNTER0 and TIMER/COUNTER1 register map

Generic Description Access Reset TIMER/ TIMER/
Name value[1] COUNTER0 COUNTER1
Address & Name Address & Name
CR3 Capture Register 3. See CR0 description. RO 0 0xE000 4038 0xE000 8038
T0CR3 T1CR3
EMR External Match Register. The EMR controls the R/W 0 0xE000 403C 0xE000 803C
external match pins MATn.0-3 (MAT0.0-3 and T0EMR T1EMR
MAT1.0-3 respectively).
CTCR Count Control Register. The CTCR selects between R/W 0 0xE000 4070 0xE000 8070
Timer and Counter mode, and in Counter mode T0CTCR T1CTCR
selects the signal and edge(s) for counting.

[1] Reset value reflects the data stored in used bits only. It does not include reserved bits content.

14.5.1 Interrupt Register (IR, TIMER0: T0IR - 0xE000 4000 and TIMER1: T1IR
- 0xE000 8000)
The Interrupt Register consists of four bits for the match interrupts and four bits for the
capture interrupts. If an interrupt is generated then the corresponding bit in the IR will be
high. Otherwise, the bit will be low. Writing a logic one to the corresponding IR bit will reset
the interrupt. Writing a zero has no effect.

Table 174: Interrupt Register (IR, TIMER0: T0IR - address 0xE000 4000 and TIMER1: T1IR - address 0xE000 8000) bit
description
Bit Symbol Description Reset value
0 MR0 Interrupt Interrupt flag for match channel 0. 0
1 MR1 Interrupt Interrupt flag for match channel 1. 0
2 MR2 Interrupt Interrupt flag for match channel 2. 0
3 MR3 Interrupt Interrupt flag for match channel 3. 0
4 CR0 Interrupt Interrupt flag for capture channel 0 event. 0
5 CR1 Interrupt Interrupt flag for capture channel 1 event. 0
6 CR2 Interrupt Interrupt flag for capture channel 2 event. 0
7 CR3 Interrupt Interrupt flag for capture channel 3 event. 0

14.5.2 Timer Control Register (TCR, TIMER0: T0TCR - 0xE000 4004 and
TIMER1: T1TCR - 0xE000 8004)
The Timer Control Register (TCR) is used to control the operation of the Timer/Counter.

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Table 175: Timer Control Register (TCR, TIMER0: T0TCR - address 0xE000 4004 and TIMER1:
T1TCR - address 0xE000 8004) bit description
Bit Symbol Description Reset value
0 Counter Enable When one, the Timer Counter and Prescale Counter are 0
enabled for counting. When zero, the counters are
disabled.
1 Counter Reset When one, the Timer Counter and the Prescale Counter 0
are synchronously reset on the next positive edge of
PCLK. The counters remain reset until TCR[1] is
returned to zero.
7:2 - Reserved, user software should not write ones to NA
reserved bits. The value read from a reserved bit is not
defined.

14.5.3 Count Control Register (CTCR, TIMER0: T0CTCR - 0xE000 4070 and
TIMER1: T1CTCR - 0xE000 8070)
The Count Control Register (CTCR) is used to select between Timer and Counter mode,
and in Counter mode to select the pin and edge(s) for counting.

When Counter Mode is chosen as a mode of operation, the CAP input (selected by the
CTCR bits 3:2) is sampled on every rising edge of the PCLK clock. After comparing two
consecutive samples of this CAP input, one of the following four events is recognized:
rising edge, falling edge, either of edges or no changes in the level of the selected CAP
input. Only if the identified event corresponds to the one selected by bits 1:0 in the CTCR
register, the Timer Counter register will be incremented.

Effective processing of the externally supplied clock to the counter has some limitations.
Since two successive rising edges of the PCLK clock are used to identify only one edge
on the CAP selected input, the frequency of the CAP input can not exceed one fourth of
the PCLK clock. Consequently, duration of the high/low levels on the same CAP input in
this case can not be shorter than 1/(2×PCLK).

Table 176: Count Control Register (CTCR, TIMER0: T0CTCR - address 0xE000 4070 and
TIMER1: T1CTCR - address 0xE000 8070) bit description
Bit Symbol Value Description Reset
value
1:0 Counter/ This field selects which rising PCLK edges can increment 00
Timer Timer’s Prescale Counter (PC), or clear PC and increment
Mode Timer Counter (TC).
00 Timer Mode: every rising PCLK edge
01 Counter Mode: TC is incremented on rising edges on the
CAP input selected by bits 3:2.
10 Counter Mode: TC is incremented on falling edges on the
CAP input selected by bits 3:2.
11 Counter Mode: TC is incremented on both edges on the CAP
input selected by bits 3:2.

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Table 176: Count Control Register (CTCR, TIMER0: T0CTCR - address 0xE000 4070 and
TIMER1: T1CTCR - address 0xE000 8070) bit description
Bit Symbol Value Description Reset
value
3:2 Count When bits 1:0 in this register are not 00, these bits select 00
Input which CAP pin is sampled for clocking:
Select 00 CAPn.0 (CAP0.0 for TIMER0 and CAP1.0 for TIMER1)
01 CAPn.1 (CAP0.1 for TIMER0 and CAP1.1 for TIMER1)
10 CAPn.2 (CAP0.2 for TIMER0 and CAP1.2 for TIMER1)
11 CAPn.3 (CAP0.3 for TIMER0 and CAP1.3 for TIMER1)
Note: If Counter mode is selected for a particular CAPn input
in the TnCTCR, the 3 bits for that input in the Capture
Control Register (TnCCR) must be programmed as 000.
However, capture and/or interrupt can be selected for the
other 3 CAPn inputs in the same timer.
7:4 - - Reserved, user software should not write ones to reserved NA
bits. The value read from a reserved bit is not defined.

14.5.4 Timer Counter (TC, TIMER0: T0TC - 0xE000 4008 and TIMER1:
T1TC - 0xE000 8008)
The 32-bit Timer Counter is incremented when the Prescale Counter reaches its terminal
count. Unless it is reset before reaching its upper limit, the TC will count up through the
value 0xFFFF FFFF and then wrap back to the value 0x0000 0000. This event does not
cause an interrupt, but a Match register can be used to detect an overflow if needed.

14.5.5 Prescale Register (PR, TIMER0: T0PR - 0xE000 400C and TIMER1:
T1PR - 0xE000 800C)
The 32-bit Prescale Register specifies the maximum value for the Prescale Counter.

14.5.6 Prescale Counter Register (PC, TIMER0: T0PC - 0xE000 4010 and
TIMER1: T1PC - 0xE000 8010)
The 32-bit Prescale Counter controls division of PCLK by some constant value before it is
applied to the Timer Counter. This allows control of the relationship of the resolution of the
timer versus the maximum time before the timer overflows. The Prescale Counter is
incremented on every PCLK. When it reaches the value stored in the Prescale Register,
the Timer Counter is incremented and the Prescale Counter is reset on the next PCLK.
This causes the TC to increment on every PCLK when PR = 0, every 2 PCLKs when
PR = 1, etc.

14.5.7 Match Registers (MR0 - MR3)

The Match register values are continuously compared to the Timer Counter value. When
the two values are equal, actions can be triggered automatically. The action possibilities
are to generate an interrupt, reset the Timer Counter, or stop the timer. Actions are
controlled by the settings in the MCR register.

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14.5.8 Match Control Register (MCR, TIMER0: T0MCR - 0xE000 4014 and
TIMER1: T1MCR - 0xE000 8014)
The Match Control Register is used to control what operations are performed when one of
the Match Registers matches the Timer Counter. The function of each of the bits is shown
in Table 177.

Table 177: Match Control Register (MCR, TIMER0: T0MCR - address 0xE000 4014 and TIMER1: T1MCR - address
0xE000 8014) bit description
Bit Symbol Value Description Reset
value
0 MR0I 1 Interrupt on MR0: an interrupt is generated when MR0 matches the value in the TC. 0
0 This interrupt is disabled
1 MR0R 1 Reset on MR0: the TC will be reset if MR0 matches it. 0
0 Feature disabled.
2 MR0S 1 Stop on MR0: the TC and PC will stop and TCR[0]=0 if MR0 matches the TC. 0
0 Feature disabled.
3 MR1I 1 Interrupt on MR1: an interrupt is generated when MR1 matches the value in the TC. 0
0 This interrupt is disabled
4 MR1R 1 Reset on MR1: the TC will be reset if MR1 matches it. 0
0 Feature disabled.
5 MR1S 1 Stop on MR1: the TC and PC will stop and TCR[0]=0 if MR1 matches the TC. 0
0 Feature disabled.
6 MR2I 1 Interrupt on MR2: an interrupt is generated when MR2 matches the value in the TC. 0
0 This interrupt is disabled
7 MR2R 1 Reset on MR2: the TC will be reset if MR2 matches it. 0
0 Feature disabled.
8 MR2S 1 Stop on MR2: the TC and PC will stop and TCR[0]=0 if MR2 matches the TC. 0
0 Feature disabled.
9 MR3I 1 Interrupt on MR3: an interrupt is generated when MR3 matches the value in the TC. 0
0 This interrupt is disabled
10 MR3R 1 Reset on MR3: the TC will be reset if MR3 matches it. 0
0 Feature disabled.
11 MR3S 1 Stop on MR3: the TC and PC will stop and TCR[0]=0 if MR3 matches the TC. 0
0 Feature disabled.
15:12 - Reserved, user software should not write ones to reserved bits. The value read from a NA
reserved bit is not defined.

14.5.9 Capture Registers (CR0 - CR3)

Each Capture register is associated with a device pin and may be loaded with the Timer
Counter value when a specified event occurs on that pin. The settings in the Capture
Control Register register determine whether the capture function is enabled, and whether
a capture event happens on the rising edge of the associated pin, the falling edge, or on
both edges.

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14.5.10 Capture Control Register (CCR, TIMER0: T0CCR - 0xE000 4028 and
TIMER1: T1CCR - 0xE000 8028)
The Capture Control Register is used to control whether one of the four Capture Registers
is loaded with the value in the Timer Counter when the capture event occurs, and whether
an interrupt is generated by the capture event. Setting both the rising and falling bits at the
same time is a valid configuration, resulting in a capture event for both edges. In the
description below, n represents the Timer number, 0 or 1.

Table 178: Capture Control Register (CCR, TIMER0: T0CCR - address 0xE000 4028 and TIMER1: T1CCR - address
0xE000 8028) bit description
Bit Symbol Value Description Reset
value
0 CAP0RE 1 Capture on CAPn.0 rising edge: a sequence of 0 then 1 on CAPn.0 will cause CR0 to be 0
loaded with the contents of TC.
0 This feature is disabled.
1 CAP0FE 1 Capture on CAPn.0 falling edge: a sequence of 1 then 0 on CAPn.0 will cause CR0 to be 0
loaded with the contents of TC.
0 This feature is disabled.
2 CAP0I 1 Interrupt on CAPn.0 event: a CR0 load due to a CAPn.0 event will generate an interrupt. 0
0 This feature is disabled.
3 CAP1RE 1 Capture on CAPn.1 rising edge: a sequence of 0 then 1 on CAPn.1 will cause CR1 to be 0
loaded with the contents of TC.
0 This feature is disabled.
4 CAP1FE 1 Capture on CAPn.1 falling edge: a sequence of 1 then 0 on CAPn.1 will cause CR1 to be 0
loaded with the contents of TC.
0 This feature is disabled.
5 CAP1I 1 Interrupt on CAPn.1 event: a CR1 load due to a CAPn.1 event will generate an interrupt. 0
0 This feature is disabled.
6 CAP2RE 1 Capture on CAPn.2 rising edge: A sequence of 0 then 1 on CAPn.2 will cause CR2 to be 0
loaded with the contents of TC.
0 This feature is disabled.
7 CAP2FE 1 Capture on CAPn.2 falling edge: a sequence of 1 then 0 on CAPn.2 will cause CR2 to be 0
loaded with the contents of TC.
0 This feature is disabled.
8 CAP2I 1 Interrupt on CAPn.2 event: a CR2 load due to a CAPn.2 event will generate an interrupt. 0
0 This feature is disabled.
9 CAP3RE 1 Capture on CAPn.3 rising edge: a sequence of 0 then 1 on CAPn.3 will cause CR3 to be 0
loaded with the contents of TC.
0 This feature is disabled.
10 CAP3FE 1 Capture on CAPn.3 falling edge: a sequence of 1 then 0 on CAPn.3 will cause CR3 to be 0
loaded with the contents of TC
0 This feature is disabled.
11 CAP3I 1 Interrupt on CAPn.3 event: a CR3 load due to a CAPn.3 event will generate an interrupt. 0
0 This feature is disabled.
15:12 - Reserved, user software should not write ones to reserved bits. The value read from a NA
reserved bit is not defined.

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14.5.11 External Match Register (EMR, TIMER0: T0EMR - 0xE000 403C; and
TIMER1: T1EMR - 0xE000 803C)
The External Match Register provides both control and status of the external match pins
MAT(0-3).

Table 179: External Match Register (EMR, TIMER0: T0EMR - address 0xE000 403C and TIMER1: T1EMR -
address0xE000 803C) bit description
Bit Symbol Description Reset
value
0 EM0 External Match 0. This bit reflects the state of output MAT0.0/MAT1.0, whether or not this 0
output is connected to its pin. When a match occurs between the TC and MR0, this output
of the timer can either toggle, go low, go high, or do nothing. Bits EMR[5:4] control the
functionality of this output.
1 EM1 External Match 1. This bit reflects the state of output MAT0.1/MAT1.1, whether or not this 0
output is connected to its pin. When a match occurs between the TC and MR1, this output
of the timer can either toggle, go low, go high, or do nothing. Bits EMR[7:6] control the
functionality of this output.
2 EM2 External Match 2. This bit reflects the state of output MAT0.2/MAT1.2, whether or not this 0
output is connected to its pin. When a match occurs between the TC and MR2, this output
of the timer can either toggle, go low, go high, or do nothing. Bits EMR[9:8] control the
functionality of this output.
3 EM3 External Match 3. This bit reflects the state of output MAT0.3/MAT1.3, whether or not this 0
output is connected to its pin. When a match occurs between the TC and MR3, this output
of the timer can either toggle, go low, go high, or do nothing. Bits EMR[11:10] control the
functionality of this output.
5:4 EMC0 External Match Control 0. Determines the functionality of External Match 0. Table 180 00
shows the encoding of these bits.
7:6 EMC1 External Match Control 1. Determines the functionality of External Match 1. Table 180 00
shows the encoding of these bits.
9:8 EMC2 External Match Control 2. Determines the functionality of External Match 2. Table 180 00
shows the encoding of these bits.
11:10 EMC3 External Match Control 3. Determines the functionality of External Match 3. Table 180 00
shows the encoding of these bits.
15:12 - Reserved, user software should not write ones to reserved bits. The value read from a NA
reserved bit is not defined.

Table 180. External match control

EMR[11:10], EMR[9:8], Function
EMR[7:6], or EMR[5:4]
00 Do Nothing.
01 Clear the corresponding External Match bit/output to 0 (MATn.m pin is LOW if pinned out).
10 Set the corresponding External Match bit/output to 1 (MATn.m pin is HIGH if pinned out).
11 Toggle the corresponding External Match bit/output.

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14.6 Example timer operation

Figure 50 shows a timer configured to reset the count and generate an interrupt on match.
The prescaler is set to 2 and the match register set to 6. At the end of the timer cycle
where the match occurs, the timer count is reset. This gives a full length cycle to the
match value. The interrupt indicating that a match occurred is generated in the next clock
after the timer reached the match value.

Figure 51 shows a timer configured to stop and generate an interrupt on match. The
prescaler is again set to 2 and the match register set to 6. In the next clock after the timer
reaches the match value, the timer enable bit in TCR is cleared, and the interrupt
indicating that a match occurred is generated.

PCLK

prescale
2 0 1 2 0 1 2 0 1 2 0 1
counter
timer
4 5 6 0 1
counter
timer counter
reset

interrupt

Fig 50. A timer cycle in which PR=2, MRx=6, and both interrupt and reset on match are enabled

PCLK

prescale counter 2 0 1 2 0

timer counter
4 5 6

TCR[0]
1 0
(counter enable)

interrupt

Fig 51. A timer cycle in which PR=2, MRx=6, and both interrupt and stop on match are enabled

14.7 Architecture
The block diagram for TIMER/COUNTER0 and TIMER/COUNTER1 is shown in
Figure 52.

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MATCH REGISTER 0

MATCH REGISTER 1

MATCH REGISTER 2

MATCH REGISTER 3

MATCH CONTROL REGISTER

EXTERNAL MATCH REGISTER

INTERRUPT REGISTER

CONTROL

=
MAT[3:0]
INTERRUPT =
CAP[3:0]
STOP ON MATCH =
RESET ON MATCH
=
LOAD[3:0]

CAPTURE CONTROL REGISTER

CSN
CAPTURE REGISTER 0 TIMER COUNTER

CAPTURE REGISTER 1 CE
CAPTURE REGISTER 2

CAPTURE REGISTER 3

TCI
PCLK
PRESCALE COUNTER

reset enable MAXVAL

TIMER CONTROL REGISTER PRESCALE REGISTER

Fig 52. Timer block diagram

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15.1 Features
• Seven match registers allow up to 6 single edge controlled or 3 double edge
controlled PWM outputs, or a mix of both types. The match registers also allow:
– Continuous operation with optional interrupt generation on match.
– Stop timer on match with optional interrupt generation.
– Reset timer on match with optional interrupt generation.
• Supports single edge controlled and/or double edge controlled PWM outputs. Single
edge controlled PWM outputs all go high at the beginning of each cycle unless the
output is a constant low. Double edge controlled PWM outputs can have either edge
occur at any position within a cycle. This allows for both positive going and negative
going pulses.
• Pulse period and width can be any number of timer counts. This allows complete
flexibility in the trade-off between resolution and repetition rate. All PWM outputs will
occur at the same repetition rate.
• Double edge controlled PWM outputs can be programmed to be either positive going
or negative going pulses.
• Match register updates are synchronized with pulse outputs to prevent generation of
erroneous pulses. Software must release new match values before they can become
effective.
• May be used as a standard timer if the PWM mode is not enabled.
• A 32-bit Timer/Counter with a programmable 32-bit Prescaler.

15.2 Description
The PWM is based on the standard Timer block and inherits all of its features, although
only the PWM function is pinned out on the LPC213x. The Timer is designed to count
cycles of the peripheral clock (PCLK) and optionally generate interrupts or perform other
actions when specified timer values occur, based on seven match registers. It also
includes four capture inputs to save the timer value when an input signal transitions, and
optionally generate an interrupt when those events occur. The PWM function is in addition
to these features, and is based on match register events.

The ability to separately control rising and falling edge locations allows the PWM to be
used for more applications. For instance, multi-phase motor control typically requires
three non-overlapping PWM outputs with individual control of all three pulse widths and
positions.

Two match registers can be used to provide a single edge controlled PWM output. One
match register (PWMMR0) controls the PWM cycle rate, by resetting the count upon
match. The other match register controls the PWM edge position. Additional single edge
controlled PWM outputs require only one match register each, since the repetition rate is
the same for all PWM outputs. Multiple single edge controlled PWM outputs will all have a
rising edge at the beginning of each PWM cycle, when an PWMMR0 match occurs.

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Three match registers can be used to provide a PWM output with both edges controlled.
Again, the PWMMR0 match register controls the PWM cycle rate. The other match
registers control the two PWM edge positions. Additional double edge controlled PWM
outputs require only two match registers each, since the repetition rate is the same for all
PWM outputs.

With double edge controlled PWM outputs, specific match registers control the rising and
falling edge of the output. This allows both positive going PWM pulses (when the rising
edge occurs prior to the falling edge), and negative going PWM pulses (when the falling
edge occurs prior to the rising edge).

Figure 53 shows the block diagram of the PWM. The portions that have been added to the
standard timer block are on the right hand side and at the top of the diagram.

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MATCH REGISTER 0 SHADOW REGISTER 0

LOAD ENABLE
MATCH REGISTER 1 SHADOW REGISTER 1
LOAD ENABLE
MATCH REGISTER 2 SHADOW REGISTER 2
LOAD ENABLE
MATCH REGISTER 3 SHADOW REGISTER 3
LOAD ENABLE
MATCH REGISTER 4 SHADOW REGISTER 4
LOAD ENABLE
MATCH REGISTER 5 SHADOW REGISTER 5
LOAD ENABLE
MATCH REGISTER 6 SHADOW REGISTER 6
LOAD ENABLE
Match 0 PWM1
S Q

Match 1 PWMENA1
R EN
MATCH 0
PWMSEL2

PWM2
LATCH ENABLE REGISTER CLEAR MUX S Q

MATCH CONTROL REGISTER Match 2 PWMENA2

R EN
INTERRUPT REGISTER =
PWMSEL3
= PWM3
CONTROL MUX S Q

M[6:0] = Match 3 PWMENA3

R EN
INTERRUPT
=
PWMSEL4
STOP ON MATCH
= PWM4
RESET ON MATCH MUX S Q

= Match 4 PWMENA4
R EN
CSN =
PWMSEL5

PWM5
MUX S Q

Match 5 PWMENA5
R EN

TIMER COUNTER PWMSEL6

CE PWM6
MUX S Q
TCI
Match 6 PWMENA6
PRESCALE COUNTER R EN

PWMENA1..6 PWMSEL2..6
ENABLE MAXVAL
RESET
PRESCALE REGISTER PWM CONTROL REGISTER
TIMER CONTROL REGISTER

Fig 53. PWM block diagram

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A sample of how PWM values relate to waveform outputs is shown in Figure 54. PWM
output logic is shown in Figure 53 that allows selection of either single or double edge
controlled PWM outputs via the muxes controlled by the PWMSELn bits. The match
register selections for various PWM outputs is shown in Table 181. This implementation
supports up to N-1 single edge PWM outputs or (N-1)/2 double edge PWM outputs, where
N is the number of match registers that are implemented. PWM types can be mixed if
desired.

PWM2

PWM4

PWM5

1 27 41 53 65 78 100
(counter is reset)

The waveforms below show a single PWM cycle and demonstrate PWM outputs under the
following conditions:
The timer is configured for PWM mode.
Match 0 is configured to reset the timer/counter when a match event occurs.
All PWM related Match registers are configured for toggle on match.
Control bits PWMSEL2 and PWMSEL4 are set.
The Match register values are as follows:
MR0 = 100 (PWM rate)
MR1 = 41, MR2 = 78 (PWM2 output)
MR3 = 53, MR4 = 27 (PWM4 output)
MR5 = 65 (PWM5 output)
Fig 54. Sample PWM waveforms

Table 181. Set and reset inputs for PWM Flip-Flops

PWM Channel Single Edge PWM (PWMSELn = 0) Double Edge PWM (PWMSELn = 1)
Set by Reset by Set by Reset by
1 Match 0 Match 1 Match 0[1] Match 1[1]
2 Match 0 Match 2 Match 1 Match 2
3 Match 0 Match 3 Match 2[2] Match 3[2]
4 Match 0 Match 4 Match 3 Match 4
5 Match 0 Match 5 Match 4[2] Match 5[2]
6 Match 0 Match 6 Match 5 Match 6

[1] Identical to single edge mode in this case since Match 0 is the neighboring match register. Essentially,
PWM1 cannot be a double edged output.
[2] It is generally not advantageous to use PWM channels 3 and 5 for double edge PWM outputs because it
would reduce the number of double edge PWM outputs that are possible. Using PWM 2, PWM4, and
PWM6 for double edge PWM outputs provides the most pairings.

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15.2.1 Rules for single edge controlled PWM outputs

1. All single edge controlled PWM outputs go high at the beginning of a PWM cycle
unless their match value is equal to 0.
2. Each PWM output will go low when its match value is reached. If no match occurs (i.e.
the match value is greater than the PWM rate), the PWM output remains continuously
high.

15.2.2 Rules for double edge controlled PWM outputs

Five rules are used to determine the next value of a PWM output when a new cycle is
about to begin:

1. The match values for the next PWM cycle are used at the end of a PWM cycle (a time
point which is coincident with the beginning of the next PWM cycle), except as noted
in rule 3.
2. A match value equal to 0 or the current PWM rate (the same as the Match channel 0
value) have the same effect, except as noted in rule 3. For example, a request for a
falling edge at the beginning of the PWM cycle has the same effect as a request for a
falling edge at the end of a PWM cycle.
3. When match values are changing, if one of the old match values is equal to the PWM
rate, it is used again once if the neither of the new match values are equal to 0 or the
PWM rate, and there was no old match value equal to 0.
4. If both a set and a clear of a PWM output are requested at the same time, clear takes
precedence. This can occur when the set and clear match values are the same as in,
or when the set or clear value equals 0 and the other value equals the PWM rate.
5. If a match value is out of range (i.e. greater than the PWM rate value), no match event
occurs and that match channel has no effect on the output. This means that the PWM
output will remain always in one state, allowing always low, always high, or no change
outputs.

15.3 Pin description

Table 182 gives a brief summary of each of PWM related pins.

Table 182. Pin summary

Pin Type Description
PWM1 Output Output from PWM channel 1.
PWM2 Output Output from PWM channel 2.
PWM3 Output Output from PWM channel 3.
PWM4 Output Output from PWM channel 4.
PWM5 Output Output from PWM channel 5.
PWM6 Output Output from PWM channel 6.

15.4 Register description

The PWM function adds new registers and registers bits as shown in Table 183 below.

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Table 183. Pulse Width Modulator (PWM) register map

Name Description Access Reset Address
value[1]
PWMIR PWM Interrupt Register. The PWMIR can be written to clear interrupts. R/W 0 0xE001 4000
The PWMIR can be read to identify which of the possible interrupt
sources are pending.
PWMTCR PWM Timer Control Register. The PWMTCR is used to control the Timer R/W 0 0xE001 4004
Counter functions. The Timer Counter can be disabled or reset through
the PWMTCR.
PWMTC PWM Timer Counter. The 32-bit TC is incremented every PWMPR+1 R/W 0 0xE001 4008
cycles of PCLK. The PWMTC is controlled through the PWMTCR.
PWMPR PWM Prescale Register. The PWMTC is incremented every PWMPR+1 R/W 0 0xE001 400C
cycles of PCLK.
PWMPC PWM Prescale Counter. The 32-bit PC is a counter which is incremented R/W 0 0xE001 4010
to the value stored in PR. When the value in PWMPR is reached, the
PWMTC is incremented. The PWMPC is observable and controllable
through the bus interface.
PWMMCR PWM Match Control Register. The PWMMCR is used to control if an R/W 0 0xE001 4014
interrupt is generated and if the PWMTC is reset when a Match occurs.
PWMMR0 PWM Match Register 0. PWMMR0 can be enabled through PWMMCR to R/W 0 0xE001 4018
reset the PWMTC, stop both the PWMTC and PWMPC, and/or generate
an interrupt when it matches the PWMTC. In addition, a match between
PWMMR0 and the PWMTC sets all PWM outputs that are in single-edge
mode, and sets PWM1 if it is in double-edge mode.
PWMMR1 PWM Match Register 1. PWMMR1 can be enabled through PWMMCR to R/W 0 0xE001 401C
reset the PWMTC, stop both the PWMTC and PWMPC, and/or generate
an interrupt when it matches the PWMTC. In addition, a match between
PWMMR1 and the PWMTC clears PWM1 in either single-edge mode or
double-edge mode, and sets PWM2 if it is in double-edge mode.
PWMMR2 PWM Match Register 2. PWMMR2 can be enabled through PWMMCR to R/W 0 0xE001 4020
reset the PWMTC, stop both the PWMTC and PWMPC, and/or generate
an interrupt when it matches the PWMTC. In addition, a match between
PWMMR2 and the PWMTC clears PWM2 in either single-edge mode or
double-edge mode, and sets PWM3 if it is in double-edge mode.
PWMMR3 PWM Match Register 3. PWMMR3 can be enabled through PWMMCR to R/W 0 0xE001 4024
reset the PWMTC, stop both the PWMTC and PWMPC, and/or generate
an interrupt when it matches the PWMTC. In addition, a match between
PWMMR3 and the PWMTC clears PWM3 in either single-edge mode or
double-edge mode, and sets PWM4 if it is in double-edge mode.
PWMMR4 PWM Match Register 4. PWMMR4 can be enabled through PWMMCR to R/W 0 0xE001 4040
reset the PWMTC, stop both the PWMTC and PWMPC, and/or generate
an interrupt when it matches the PWMTC. In addition, a match between
PWMMR4 and the PWMTC clears PWM4 in either single-edge mode or
double-edge mode, and sets PWM5 if it is in double-edge mode.
PWMMR5 PWM Match Register 5. PWMMR5 can be enabled through PWMMCR to R/W 0 0xE001 4044
reset the PWMTC, stop both the PWMTC and PWMPC, and/or generate
an interrupt when it matches the PWMTC. In addition, a match between
PWMMR5 and the PWMTC clears PWM5 in either single-edge mode or
double-edge mode, and sets PWM6 if it is in double-edge mode.

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Table 183. Pulse Width Modulator (PWM) register map

Name Description Access Reset Address
value[1]
PWMMR6 PWM Match Register 6. PWMMR6 can be enabled through PWMMCR to R/W 0 0xE001 4048
reset the PWMTC, stop both the PWMTC and PWMPC, and/or generate
an interrupt when it matches the PWMTC. In addition, a match between
PWMMR6 and the PWMTC clears PWM6 in either single-edge mode or
double-edge mode.
PWMPCR PWM Control Register. Enables PWM outputs and selects PWM channel R/W 0 0xE001 404C
types as either single edge or double edge controlled.
PWMLER PWM Latch Enable Register. Enables use of new PWM match values. R/W 0 0xE001 4050

[1] Reset value reflects the data stored in used bits only. It does not include reserved bits content.

15.4.1 PWM Interrupt Register (PWMIR - 0xE001 4000)

The PWM Interrupt Register consists of eleven bits (Table 184), seven for the match
interrupts and four reserved for the future use. If an interrupt is generated then the
corresponding bit in the PWMIR will be high. Otherwise, the bit will be low. Writing a logic
one to the corresponding IR bit will reset the interrupt. Writing a zero has no effect.

Table 184: PWM Interrupt Register (PWMIR - address 0xE001 4000) bit description
Bit Symbol Description Reset
value
0 PWMMR0 Interrupt Interrupt flag for PWM match channel 0. 0
1 PWMMR1 Interrupt Interrupt flag for PWM match channel 1. 0
2 PWMMR2 Interrupt Interrupt flag for PWM match channel 2. 0
3 PWMMR3 Interrupt Interrupt flag for PWM match channel 3. 0
7:4 - Reserved, user software should not write ones to reserved NA
bits. The value read from a reserved bit is not defined.
8 PWMMR4 Interrupt Interrupt flag for PWM match channel 4. 0
9 PWMMR5 Interrupt Interrupt flag for PWM match channel 5. 0
10 PWMMR6 Interrupt Interrupt flag for PWM match channel 6. 0
15:11 - Reserved, user software should not write ones to reserved NA
bits. The value read from a reserved bit is not defined.

15.4.2 PWM Timer Control Register (PWMTCR - 0xE001 4004)

The PWM Timer Control Register (PWMTCR) is used to control the operation of the PWM
Timer Counter. The function of each of the bits is shown in Table 185.

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Table 185: PWM Timer Control Register (PWMTCR - address 0xE001 4004) bit description
Bit Symbol Description Reset value
0 Counter Enable When one, the PWM Timer Counter and PWM Prescale 0
Counter are enabled for counting. When zero, the
counters are disabled.
1 Counter Reset When one, the PWM Timer Counter and the PWM 0
Prescale Counter are synchronously reset on the next
positive edge of PCLK. The counters remain reset until
TCR[1] is returned to zero.
2 - Reserved, user software should not write ones to NA
reserved bits. The value read from a reserved bit is not
defined.
3 PWM Enable When one, PWM mode is enabled. PWM mode causes 0
shadow registers to operate in connection with the
Match registers. A program write to a Match register will
not have an effect on the Match result until the
corresponding bit in PWMLER has been set, followed by
the occurrence of a PWM Match 0 event. Note that the
PWM Match register that determines the PWM rate
(PWM Match 0) must be set up prior to the PWM being
enabled. Otherwise a Match event will not occur to
cause shadow register contents to become effective.
Remark: The PWM Enable bit (bit 3 in the PWMxTCR)
needs to be always set to 1 for PWM operation.
Otherwise, the PWM will behave as standard timer.
7:4 - Reserved, user software should not write ones to NA
reserved bits. The value read from a reserved bit is not
defined.

15.4.3 PWM Timer Counter (PWMTC - 0xE001 4008)

The 32-bit PWM Timer Counter is incremented when the Prescale Counter reaches its
terminal count. Unless it is reset before reaching its upper limit, the PWMTC will count up
through the value 0xFFFF FFFF and then wrap back to the value 0x0000 0000. This
event does not cause an interrupt, but a Match register can be used to detect an overflow
if needed.

15.4.4 PWM Prescale Register (PWMPR - 0xE001 400C)

The 32-bit PWM Prescale Register specifies the maximum value for the PWM Prescale
Counter.

15.4.5 PWM Prescale Counter register (PWMPC - 0xE001 4010)

The 32-bit PWM Prescale Counter controls division of PCLK by some constant value
before it is applied to the PWM Timer Counter. This allows control of the relationship of the
resolution of the timer versus the maximum time before the timer overflows. The PWM
Prescale Counter is incremented on every PCLK. When it reaches the value stored in the
PWM Prescale Register, the PWM Timer Counter is incremented and the PWM Prescale
Counter is reset on the next PCLK. This causes the PWM TC to increment on every PCLK
when PWMPR = 0, every 2 PCLKs when PWMPR = 1, etc.

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15.4.6 PWM Match Registers (PWMMR0 - PWMMR6)

The 32-bit PWM Match register values are continuously compared to the PWM Timer
Counter value. When the two values are equal, actions can be triggered automatically.
The action possibilities are to generate an interrupt, reset the PWM Timer Counter, or stop
the timer. Actions are controlled by the settings in the PWMMCR register.

15.4.7 PWM Match Control Register (PWMMCR - 0xE001 4014)

The PWM Match Control Register is used to control what operations are performed when
one of the PWM Match Registers matches the PWM Timer Counter. The function of each
of the bits is shown in Table 186.

Table 186: PWM Match Control Register (PWMMCR - address 0xE001 4014) bit description
Bit Symbol Value Description Reset
value
0 PWMMR0I 1 Interrupt on PWMMR0: an interrupt is generated when PWMMR0 matches the value 0
in the PWMTC.
0 This interrupt is disabled.
1 PWMMR0R 1 Reset on PWMMR0: the PWMTC will be reset if PWMMR0 matches it. 0
0 This feature is disabled.
2 PWMMR0S 1 Stop on PWMMR0: the PWMTC and PWMPC will be stopped and PWMTCR[0] will 0
be set to 0 if PWMMR0 matches the PWMTC.
0 This feature is disabled
3 PWMMR1I 1 Interrupt on PWMMR1: an interrupt is generated when PWMMR1 matches the value 0
in the PWMTC.
0 This interrupt is disabled.
1 PWMMR1R 1 Reset on PWMMR1: the PWMTC will be reset if PWMMR1 matches it. 0
0 This feature is disabled.
5 PWMMR1S 1 Stop on PWMMR1: the PWMTC and PWMPC will be stopped and PWMTCR[0] will 0
be set to 0 if PWMMR1 matches the PWMTC.
0 This feature is disabled.
6 PWMMR2I 1 Interrupt on PWMMR2: an interrupt is generated when PWMMR2 matches the value 0
in the PWMTC.
0 This interrupt is disabled.
7 PWMMR2R 1 Reset on PWMMR2: the PWMTC will be reset if PWMMR2 matches it. 0
0 This feature is disabled.
8 PWMMR2S 1 Stop on PWMMR2: the PWMTC and PWMPC will be stopped and PWMTCR[0] will 0
be set to 0 if PWMMR2 matches the PWMTC.
0 This feature is disabled
9 PWMMR3I 1 Interrupt on PWMMR3: an interrupt is generated when PWMMR3 matches the value 0
in the PWMTC.
0 This interrupt is disabled.
10 PWMMR3R 1 Reset on PWMMR3: the PWMTC will be reset if PWMMR3 matches it. 0
0 This feature is disabled
11 PWMMR3S 1 Stop on PWMMR3: The PWMTC and PWMPC will be stopped and PWMTCR[0] will 0
be set to 0 if PWMMR3 matches the PWMTC.
0 This feature is disabled

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Table 186: PWM Match Control Register (PWMMCR - address 0xE001 4014) bit description
Bit Symbol Value Description Reset
value
12 PWMMR4I 1 Interrupt on PWMMR4: An interrupt is generated when PWMMR4 matches the value 0
in the PWMTC.
0 This interrupt is disabled.
13 PWMMR4R 1 Reset on PWMMR4: the PWMTC will be reset if PWMMR4 matches it. 0
0 This feature is disabled.
14 PWMMR4S 1 Stop on PWMMR4: the PWMTC and PWMPC will be stopped and PWMTCR[0] will 0
be set to 0 if PWMMR4 matches the PWMTC.
0 This feature is disabled
15 PWMMR5I 1 Interrupt on PWMMR5: An interrupt is generated when PWMMR5 matches the value 0
in the PWMTC.
0 This interrupt is disabled.
16 PWMMR5R 1 Reset on PWMMR5: the PWMTC will be reset if PWMMR5 matches it. 0
0 This feature is disabled.
17 PWMMR5S 1 Stop on PWMMR5: the PWMTC and PWMPC will be stopped and PWMTCR[0] will 0
be set to 0 if PWMMR5 matches the PWMTC.
0 This feature is disabled
18 PWMMR6I 1 Interrupt on PWMMR6: an interrupt is generated when PWMMR6 matches the value 0
in the PWMTC.
0 This interrupt is disabled.
19 PWMMR6R 1 Reset on PWMMR6: the PWMTC will be reset if PWMMR6 matches it. 0
0 This feature is disabled.
20 PWMMR6S 1 Stop on PWMMR6: the PWMTC and PWMPC will be stopped and PWMTCR[0] will 0
be set to 0 if PWMMR6 matches the PWMTC.
0 This feature is disabled
31:21 - Reserved, user software should not write ones to reserved bits. The value read from NA
a reserved bit is not defined.

15.4.8 PWM Control Register (PWMPCR - 0xE001 404C)

The PWM Control Register is used to enable and select the type of each PWM channel.
The function of each of the bits are shown in Table 187.

Table 187: PWM Control Register (PWMPCR - address 0xE001 404C) bit description
Bit Symbol Value Description Reset
value
1:0 - Reserved, user software should not write ones to reserved bits. The value read from NA
a reserved bit is not defined.
2 PWMSEL2 1 Selects double edge controlled mode for the PWM2 output. 0
0 Selects single edge controlled mode for PWM2.
3 PWMSEL3 1 Selects double edge controlled mode for the PWM3 output. 0
0 Selects single edge controlled mode for PWM3.
4 PWMSEL4 1 Selects double edge controlled mode for the PWM4 output. 0
0 Selects single edge controlled mode for PWM4.

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Table 187: PWM Control Register (PWMPCR - address 0xE001 404C) bit description
Bit Symbol Value Description Reset
value
5 PWMSEL5 1 Selects double edge controlled mode for the PWM5 output. 0
0 Selects single edge controlled mode for PWM5.
6 PWMSEL6 1 Selects double edge controlled mode for the PWM6 output. 0
0 Selects single edge controlled mode for PWM6.
8:7 - Reserved, user software should not write ones to reserved bits. The value read from NA
a reserved bit is not defined.
9 PWMENA1 1 The PWM1 output enabled. 0
0 The PWM1 output disabled.
10 PWMENA2 1 The PWM2 output enabled. 0
0 The PWM2 output disabled.
11 PWMENA3 1 The PWM3 output enabled. 0
0 The PWM3 output disabled.
12 PWMENA4 1 The PWM4 output enabled. 0
0 The PWM4 output disabled.
13 PWMENA5 1 The PWM5 output enabled. 0
0 The PWM5 output disabled.
14 PWMENA6 1 The PWM6 output enabled. 0
0 The PWM6 output disabled.
15 - Reserved, user software should not write ones to reserved bits. The value read from NA
a reserved bit is not defined.

15.4.9 PWM Latch Enable Register (PWMLER - 0xE001 4050)

The PWM Latch Enable Register is used to control the update of the PWM Match
registers when they are used for PWM generation. When software writes to the location of
a PWM Match register while the Timer is in PWM mode, the value is held in a shadow
register. When a PWM Match 0 event occurs (normally also resetting the timer in PWM
mode), the contents of shadow registers will be transferred to the actual Match registers if
the corresponding bit in the Latch Enable Register has been set. At that point, the new
values will take effect and determine the course of the next PWM cycle. Once the transfer
of new values has taken place, all bits of the LER are automatically cleared. Until the
corresponding bit in the PWMLER is set and a PWM Match 0 event occurs, any value
written to the PWM Match registers has no effect on PWM operation.

For example, if PWM2 is configured for double edge operation and is currently running, a
typical sequence of events for changing the timing would be:

• Write a new value to the PWM Match1 register.

• Write a new value to the PWM Match2 register.
• Write to the PWMLER, setting bits 1 and 2 at the same time.
• The altered values will become effective at the next reset of the timer (when a PWM
Match 0 event occurs).

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The order of writing the two PWM Match registers is not important, since neither value will
be used until after the write to PWMLER. This insures that both values go into effect at the
same time, if that is required. A single value may be altered in the same way if needed.

The function of each of the bits in the PWMLER is shown in Table 188.

Table 188: PWM Latch Enable Register (PWMLER - address 0xE001 4050) bit description
Bit Symbol Description Reset
value
0 Enable PWM Writing a one to this bit allows the last value written to the PWM 0
Match 0 Latch Match 0 register to be become effective when the timer is next
reset by a PWM Match event. See Section 15.4.7 “PWM Match
Control Register (PWMMCR - 0xE001 4014)”.
1 Enable PWM Writing a one to this bit allows the last value written to the PWM 0
Match 1 Latch Match 1 register to be become effective when the timer is next
reset by a PWM Match event. See Section 15.4.7 “PWM Match
Control Register (PWMMCR - 0xE001 4014)”.
2 Enable PWM Writing a one to this bit allows the last value written to the PWM 0
Match 2 Latch Match 2 register to be become effective when the timer is next
reset by a PWM Match event. See Section 15.4.7 “PWM Match
Control Register (PWMMCR - 0xE001 4014)”.
3 Enable PWM Writing a one to this bit allows the last value written to the PWM 0
Match 3 Latch Match 3 register to be become effective when the timer is next
reset by a PWM Match event. See Section 15.4.7 “PWM Match
Control Register (PWMMCR - 0xE001 4014)”.
4 Enable PWM Writing a one to this bit allows the last value written to the PWM 0
Match 4 Latch Match 4 register to be become effective when the timer is next
reset by a PWM Match event. See Section 15.4.7 “PWM Match
Control Register (PWMMCR - 0xE001 4014)”.
5 Enable PWM Writing a one to this bit allows the last value written to the PWM 0
Match 5 Latch Match 5 register to be become effective when the timer is next
reset by a PWM Match event. See Section 15.4.7 “PWM Match
Control Register (PWMMCR - 0xE001 4014)”.
6 Enable PWM Writing a one to this bit allows the last value written to the PWM 0
Match 6 Latch Match 6 register to be become effective when the timer is next
reset by a PWM Match event. See Section 15.4.7 “PWM Match
Control Register (PWMMCR - 0xE001 4014)”.
7 - Reserved, user software should not write ones to reserved bits. NA
The value read from a reserved bit is not defined.

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16.1 Features
• Internally resets chip if not periodically reloaded.
• Debug mode.
• Enabled by software but requires a hardware reset or a watchdog reset/interrupt to be
disabled.
• Incorrect/Incomplete feed sequence causes reset/interrupt if enabled.
• Flag to indicate Watchdog reset.
• Programmable 32-bit timer with internal pre-scaler.
• Selectable time period from (TPCLK x 256 x 4) to (TPCLK x 232 x 4) in multiples of
TPCLK x 4.

16.2 Applications
The purpose of the watchdog is to reset the microcontroller within a reasonable amount of
time if it enters an erroneous state. When enabled, the watchdog will generate a system
reset if the user program fails to feed (or reload) the watchdog within a predetermined
amount of time.

For interaction of the on-chip watchdog and other peripherals, especially the reset and
boot-up procedures, please read Section 4.10 “Reset” on page 43 of this document.

16.3 Description
The watchdog consists of a divide by 4 fixed pre-scaler and a 32-bit counter. The clock is
fed to the timer via a pre-scaler. The timer decrements when clocked. The minimum value
from which the counter decrements is 0xFF. Setting a value lower than 0xFF causes 0xFF
to be loaded in the counter. Hence the minimum watchdog interval is (TPCLK x 256 x 4)
and the maximum watchdog interval is (TPCLK x 232 x 4) in multiples of (TPCLK x 4). The
watchdog should be used in the following manner:

• Set the watchdog timer constant reload value in WDTC register.

• Setup mode in WDMOD register.
• Start the watchdog by writing 0xAA followed by 0x55 to the WDFEED register.
• Watchdog should be fed again before the watchdog counter underflows to prevent
reset/interrupt.

When the Watchdog counter underflows, the program counter will start from 0x0000 0000
as in the case of external reset. The Watchdog Time-Out Flag (WDTOF) can be examined
to determine if the watchdog has caused the reset condition. The WDTOF flag must be
cleared by software.

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16.4 Register description

The watchdog contains 4 registers as shown in Table 189 below.

Table 189. Watchdog register map

Name Description Access Reset Address
value[1]
WDMOD Watchdog Mode register. This register contains the R/W 0 0xE000 0000
basic mode and status of the Watchdog Timer.
WDTC Watchdog Timer Constant register. This register R/W 0xFF 0xE000 0004
determines the time-out value.
WDFEED Watchdog Feed sequence register. Writing 0xAA WO NA 0xE000 0008
followed by 0x55 to this register reloads the
Watchdog timer to its preset value.
WDTV Watchdog Timer Value register. This register reads RO 0xFF 0xE000 000C
out the current value of the Watchdog timer.

[1] Reset value reflects the data stored in used bits only. It does not include reserved bits content.

16.4.1 Watchdog Mode register (WDMOD - 0xE000 0000)

The WDMOD register controls the operation of the watchdog as per the combination of
WDEN and RESET bits.

Table 190. Watchdog operating modes selection

WDEN WDRESET Mode of Operation
0 X (0 or 1) Debug/Operate without the watchdog running.
1 0 Watchdog Interrupt Mode: debug with the Watchdog interrupt but no
WDRESET enabled.
When this mode is selected, a watchdog counter underflow will set the
WDINT flag and the watchdog interrupt request will be generated.
1 1 Watchdog Reset Mode: operate with the watchdog interrupt and
WDRESET enabled.
When this mode is selected, a watchdog counter underflow will reset
the microcontroller. While the watchdog interrupt is also enabled in
this case (WDEN = 1) it will not be recognized since the watchdog
reset will clear the WDINT flag.

Once the WDEN and/or WDRESET bits are set they can not be cleared by software. Both
flags are cleared by an external reset or a watchdog timer underflow.

WDTOF The Watchdog Time-Out Flag is set when the watchdog times out. This flag is
cleared by software.

WDINT The Watchdog Interrupt Flag is set when the watchdog times out. This flag is
cleared when any reset occurs. Once the watchdog interrupt is serviced, it can be
disabled in the VIC or the watchdog interrupt request will be generated indefinitely.

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Table 191: Watchdog Mode register (WDMOD - address 0xE000 0000) bit description
Bit Symbol Description Reset value
0 WDEN WDEN Watchdog interrupt Enable bit (Set Only). 0
1 WDRESET WDRESET Watchdog Reset Enable bit (Set Only). 0
2 WDTOF WDTOF Watchdog Time-Out Flag. 0 (Only after
external reset)
3 WDINT WDINT Watchdog interrupt Flag (Read Only). 0
7:4 - Reserved, user software should not write ones to reserved NA
bits. The value read from a reserved bit is not defined.

16.4.2 Watchdog Timer Constant register (WDTC - 0xE000 0004)

The WDTC register determines the time-out value. Every time a feed sequence occurs
the WDTC content is reloaded in to the watchdog timer. It’s a 32-bit register with 8 LSB set
to 1 on reset. Writing values below 0xFF will cause 0xFF to be loaded to the WDTC. Thus
the minimum time-out interval is TPCLK × 256 × 4.

Table 192: Watchdog Timer Constant register (WDTC - address 0xE000 0004) bit description
Bit Symbol Description Reset value
31:0 Count Watchdog time-out interval. 0x0000 00FF

16.4.3 Watchdog Feed register (WDFEED - 0xE000 0008)

Writing 0xAA followed by 0x55 to this register will reload the watchdog timer to the WDTC
value. This operation will also start the watchdog if it is enabled via the WDMOD register.
Setting the WDEN bit in the WDMOD register is not sufficient to enable the watchdog. A
valid feed sequence must first be completed before the Watchdog is capable of
generating an interrupt/reset. Until then, the watchdog will ignore feed errors. Once 0xAA
is written to the WDFEED register the next operation in the Watchdog register space
should be a WRITE (0x55) to the WDFEED register otherwise the watchdog is triggered.
The interrupt/reset will be generated during the second PCLK following an incorrect
access to a watchdog timer register during a feed sequence.

Interrupts should be disabled during the feed sequence. An abort condition will occur if an
interrupt happens during the feed sequence.

Table 193: Watchdog Feed register (WDFEED - address 0xE000 0008) bit description
Bit Symbol Description Reset value
7:0 Feed Feed value should be 0xAA followed by 0x55. NA

16.4.4 Watchdog Timer Value register (WDTV - 0xE000 000C)

The WDTV register is used to read the current value of watchdog timer.

Table 194: Watchdog Timer Value register (WDTV - address 0xE000 000C) bit description
Bit Symbol Description Reset value
31:0 Count Counter timer value. 0x0000 00FF

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16.5 Block diagram

The block diagram of the Watchdog is shown below in the Figure 55.

WDTC
feed sequence

feed error

feed ok
WDFEED

PLCK 32 BIT DOWN underflow

/4 COUNTER

enable
count 1

WDTV CURRENT WD
register TIMER COUNT

SHADOW BIT

WDMOD
register WDEN 2 WDTOF WDINT WDRESET 2

reset

interrupt

(1) Counter is enabled only when the WDEN bit is set and a valid feed sequence is done.
(2) WDEN and WDRESET are sticky bits. Once set they can’t be cleared until the watchdog
underflows or an external reset occurs.
Fig 55. Watchdog block diagram

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Chapter 17: LPC213x RTC
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17.1 Features
• Measures the passage of time to maintain a calendar and clock.
• Ultra Low Power design to support battery powered systems.
• Provides Seconds, Minutes, Hours, Day of Month, Month, Year, Day of Week, and
Day of Year.
• Dedicated 32 kHz oscillator or programmable prescaler from APB clock.
• Dedicated power supply pin can be connected to a battery or to the main 3.3 V.

17.2 Description
The Real Time Clock (RTC) is a set of counters for measuring time when system power is
on, and optionally when it is off. It uses little power in Power-down mode. On the
LPC213x, the RTC can be clocked by a separate 32.768 KHz oscillator or by a
programmable prescale divider based on the APB clock. Also, the RTC is powered by its
own power supply pin, VBAT, which can be connected to a battery or to the same 3.3 V
supply used by the rest of the device.

17.3 Architecture

RTC OSCILLATOR
CLK32k
MUX
CLOCK GENERATOR
REFERENCE CLOCK DIVIDER
(PRESCALER)

strobe
CLK1 CCLK

ALARM
TIME COUNTERS COMPARATORS
REGISTERS

counter COUNTER INCREMENT ALARM MASK

enables INTERRUPT ENABLE REGISTER

INTERRUPT GENERATOR

Fig 56. RTC block diagram

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17.4 Register description

The RTC includes a number of registers. The address space is split into four sections by
functionality. The first eight addresses are the Miscellaneous Register Group
(Section 17.4.2). The second set of eight locations are the Time Counter Group
(Section 17.4.12). The third set of eight locations contain the Alarm Register Group
(Section 17.4.14). The remaining registers control the Reference Clock Divider.

The Real Time Clock includes the register shown in Table 195. Detailed descriptions of
the registers follow.

Table 195. Real Time Clock (RTC) register map

Name Size Description Access Reset Address
value[1]
ILR 2 Interrupt Location Register R/W * 0xE002 4000
CTC 15 Clock Tick Counter RO * 0xE002 4004
CCR 4 Clock Control Register R/W * 0xE002 4008
CIIR 8 Counter Increment Interrupt Register R/W * 0xE002 400C
AMR 8 Alarm Mask Register R/W * 0xE002 4010
CTIME0 32 Consolidated Time Register 0 RO * 0xE002 4014
CTIME1 32 Consolidated Time Register 1 RO * 0xE002 4018
CTIME2 32 Consolidated Time Register 2 RO * 0xE002 401C
SEC 6 Seconds Counter R/W * 0xE002 4020
MIN 6 Minutes Register R/W * 0xE002 4024
HOUR 5 Hours Register R/W * 0xE002 4028
DOM 5 Day of Month Register R/W * 0xE002 402C
DOW 3 Day of Week Register R/W * 0xE002 4030
DOY 9 Day of Year Register R/W * 0xE002 4034
MONTH 4 Months Register R/W * 0xE002 4038
YEAR 12 Years Register R/W * 0xE002 403C
ALSEC 6 Alarm value for Seconds R/W * 0xE002 4060
ALMIN 6 Alarm value for Minutes R/W * 0xE002 4064
ALHOUR 5 Alarm value for Seconds R/W * 0xE002 4068
ALDOM 5 Alarm value for Day of Month R/W * 0xE002 406C
ALDOW 3 Alarm value for Day of Week R/W * 0xE002 4070
ALDOY 9 Alarm value for Day of Year R/W * 0xE002 4074
ALMON 4 Alarm value for Months R/W * 0xE002 4078
ALYEAR 12 Alarm value for Year R/W * 0xE002 407C
PREINT 13 Prescaler value, integer portion R/W 0 0xE002 4080
PREFRAC 15 Prescaler value, integer portion R/W 0 0xE002 4084

[1] Registers in the RTC other than those that are part of the Prescaler are not affected by chip Reset. These
registers must be initialized by software if the RTC is enabled. Reset value reflects the data stored in used
bits only. It does not include reserved bits content.

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17.4.1 RTC interrupts

Interrupt generation is controlled through the Interrupt Location Register (ILR), Counter
Increment Interrupt Register (CIIR), the alarm registers, and the Alarm Mask Register
(AMR). Interrupts are generated only by the transition into the interrupt state. The ILR
separately enables CIIR and AMR interrupts. Each bit in CIIR corresponds to one of the
time counters. If CIIR is enabled for a particular counter, then every time the counter is
incremented an interrupt is generated. The alarm registers allow the user to specify a date
and time for an interrupt to be generated. The AMR provides a mechanism to mask alarm
compares. If all nonmasked alarm registers match the value in their corresponding time
counter, then an interrupt is generated.

The RTC interrupt can bring the microcontroller out of power-down mode if the RTC is
operating from its own oscillator on the RTCX1-2 pins. When the RTC interrupt is enabled
for wake-up and its selected event occurs, XTAL1/2 pins associated oscillator wake-up
cycle is started. For details on the RTC based wake-up process see Section 4.5.3
“Interrupt Wake-up register (INTWAKE - 0xE01F C144)” on page 28 and Section 4.12
“Wake-up timer” on page 46.

17.4.2 Miscellaneous register group

Table 196 summarizes the registers located from 0 to 7 of A[6:2]. More detailed
descriptions follow.

Table 196. Miscellaneous registers

Name Size Description Access Address
ILR 2 Interrupt Location. Reading this location R/W 0xE002 4000
indicates the source of an interrupt. Writing a
one to the appropriate bit at this location clears
the associated interrupt.
CTC 15 Clock Tick Counter. Value from the clock RO 0xE002 4004
divider.
CCR 4 Clock Control Register. Controls the function of R/W 0xE002 4008
the clock divider.
CIIR 8 Counter Increment Interrupt. Selects which R/W 0xE002 400C
counters will generate an interrupt when they
are incremented.
AMR 8 Alarm Mask Register. Controls which of the R/W 0xE002 4010
alarm registers are masked.
CTIME0 32 Consolidated Time Register 0 RO 0xE002 4014
CTIME1 32 Consolidated Time Register 1 RO 0xE002 4018
CTIME2 32 Consolidated Time Register 2 RO 0xE002 401C

17.4.3 Interrupt Location Register (ILR - 0xE002 4000)

The Interrupt Location Register is a 2-bit register that specifies which blocks are
generating an interrupt (see Table 197). Writing a one to the appropriate bit clears the
corresponding interrupt. Writing a zero has no effect. This allows the programmer to read
this register and write back the same value to clear only the interrupt that is detected by
the read.

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Table 197: Interrupt Location Register (ILR - address 0xE002 4000) bit description
Bit Symbol Description Reset
value
0 RTCCIF When one, the Counter Increment Interrupt block generated an interrupt. NA
Writing a one to this bit location clears the counter increment interrupt.
1 RTCALF When one, the alarm registers generated an interrupt. Writing a one to NA
this bit location clears the alarm interrupt.
7:2 - Reserved, user software should not write ones to reserved bits. The NA
value read from a reserved bit is not defined.

17.4.4 Clock Tick Counter Register (CTCR - 0xE002 4004)

The Clock Tick Counter is read only. It can be reset to zero through the Clock Control
Register (CCR). The CTC consists of the bits of the clock divider counter.

Table 198: Clock Tick Counter Register (CTCR - address 0xE002 4004) bit description
Bit Symbol Description Reset
value
1 - Reserved -
14:1 Clock Tick Prior to the Seconds counter, the CTC counts 32,768 clocks per NA
Counter second. Due to the RTC Prescaler, these 32,768 time increments may
not all be of the same duration. Refer to the Section 17.6 “Reference
clock divider (prescaler)” on page 226 for details.
15 - Reserved, user software should not write ones to reserved bits. The NA
value read from a reserved bit is not defined.

If the RTC is driven by the external 32.786 kHz oscillator, subsequent read operations of
the CTCR may yield an incorrect result. The CTCR is implemented as a 15-bit ripple
counter so that not all 15 bits change simultaneously. The LSB changes first, then the
next, and so forth. Since the 32.786 kHz oscillator is asynchronous to the CPU clock, it is
possible for a CTC read to occur during the time when the CTCR bits are changing
resulting in an incorrect large difference between back-to-back reads.
If the RTC is driven by the PCLK, the CPU and the RTC are synchronous because both of
their clocks are driven from the PLL output. Therefore, incorrect consecutive reads can
not occur.

17.4.5 Clock Control Register (CCR - 0xE002 4008)

The clock register is a 5-bit register that controls the operation of the clock divide circuit.
Each bit of the clock register is described in Table 199.

Table 199: Clock Control Register (CCR - address 0xE002 4008) bit description
Bit Symbol Description Reset
value
0 CLKEN Clock Enable. When this bit is a one the time counters are enabled. NA
When it is a zero, they are disabled so that they may be initialized.
1 CTCRST CTC Reset. When one, the elements in the Clock Tick Counter are NA
reset. The elements remain reset until CCR[1] is changed to zero.

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Table 199: Clock Control Register (CCR - address 0xE002 4008) bit description
Bit Symbol Description Reset
value
3:2 CTTEST Test Enable. These bits should always be zero during normal NA
operation.
4 CLKSRC If this bit is 0, the Clock Tick Counter takes its clock from the Prescaler. NA
If this bit is 1, the CTC takes its clock from the 32 kHz oscillator that’s
connected to the RTCX1 and RTCX2 pins (see Section 17.7 “RTC
external 32 kHz oscillator component selection” for hardware details).
7:5 - Reserved, user software should not write ones to reserved bits. The NA
value read from a reserved bit is not defined.

17.4.6 Counter Increment Interrupt Register (CIIR - 0xE002 400C)

The Counter Increment Interrupt Register (CIIR) gives the ability to generate an interrupt
every time a counter is incremented. This interrupt remains valid until cleared by writing a
one to bit zero of the Interrupt Location Register (ILR[0]).

Table 200: Counter Increment Interrupt Register (CIIR - address 0xE002 400C) bit description
Bit Symbol Description Reset
value
0 IMSEC When 1, an increment of the Second value generates an interrupt. NA
1 IMMIN When 1, an increment of the Minute value generates an interrupt. NA
2 IMHOUR When 1, an increment of the Hour value generates an interrupt. NA
3 IMDOM When 1, an increment of the Day of Month value generates an NA
interrupt.
4 IMDOW When 1, an increment of the Day of Week value generates an interrupt. NA
5 IMDOY When 1, an increment of the Day of Year value generates an interrupt. NA
6 IMMON When 1, an increment of the Month value generates an interrupt. NA
7 IMYEAR When 1, an increment of the Year value generates an interrupt. NA

17.4.7 Alarm Mask Register (AMR - 0xE002 4010)

The Alarm Mask Register (AMR) allows the user to mask any of the alarm registers.
Table 201 shows the relationship between the bits in the AMR and the alarms. For the
alarm function, every non-masked alarm register must match the corresponding time
counter for an interrupt to be generated. The interrupt is generated only when the counter
comparison first changes from no match to match. The interrupt is removed when a one is
written to the appropriate bit of the Interrupt Location Register (ILR). If all mask bits are
set, then the alarm is disabled.

Table 201: Alarm Mask Register (AMR - address 0xE002 4010) bit description
Bit Symbol Description Reset
value
0 AMRSEC When 1, the Second value is not compared for the alarm. NA
1 AMRMIN When 1, the Minutes value is not compared for the alarm. NA
2 AMRHOUR When 1, the Hour value is not compared for the alarm. NA
3 AMRDOM When 1, the Day of Month value is not compared for the alarm. NA
4 AMRDOW When 1, the Day of Week value is not compared for the alarm. NA

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Table 201: Alarm Mask Register (AMR - address 0xE002 4010) bit description
Bit Symbol Description Reset
value
5 AMRDOY When 1, the Day of Year value is not compared for the alarm. NA
6 AMRMON When 1, the Month value is not compared for the alarm. NA
7 AMRYEAR When 1, the Year value is not compared for the alarm. NA

17.4.8 Consolidated time registers

The values of the Time Counters can optionally be read in a consolidated format which
allows the programmer to read all time counters with only three read operations. The
various registers are packed into 32-bit values as shown in Table 202, Table 203, and
Table 204. The least significant bit of each register is read back at bit 0, 8, 16, or 24.

The Consolidated Time Registers are read only. To write new values to the Time
Counters, the Time Counter addresses should be used.

17.4.9 Consolidated Time register 0 (CTIME0 - 0xE002 4014)

The Consolidated Time Register 0 contains the low order time values: Seconds, Minutes,
Hours, and Day of Week.

Table 202: Consolidated Time register 0 (CTIME0 - address 0xE002 4014) bit description
Bit Symbol Description Reset
value
5:0 Seconds Seconds value in the range of 0 to 59 NA
7:6 - Reserved, user software should not write ones to reserved bits. NA
The value read from a reserved bit is not defined.
13:8 Minutes Minutes value in the range of 0 to 59 NA
15:14 - Reserved, user software should not write ones to reserved bits. NA
The value read from a reserved bit is not defined.
20:16 Hours Hours value in the range of 0 to 23 NA
23:21 - Reserved, user software should not write ones to reserved bits. NA
The value read from a reserved bit is not defined.
26:24 Day Of Week Day of week value in the range of 0 to 6 NA
31:27 - Reserved, user software should not write ones to reserved bits. NA
The value read from a reserved bit is not defined.

17.4.10 Consolidated Time register 1 (CTIME1 - 0xE002 4018)

The Consolidate Time register 1 contains the Day of Month, Month, and Year values.

Table 203: Consolidated Time register 1 (CTIME1 - address 0xE002 4018) bit description
Bit Symbol Description Reset
value
4:0 Day of Month Day of month value in the range of 1 to 28, 29, 30, or 31 NA
(depending on the month and whether it is a leap year).
7:5 - Reserved, user software should not write ones to reserved bits. NA
The value read from a reserved bit is not defined.
11:8 Month Month value in the range of 1 to 12. NA

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Table 203: Consolidated Time register 1 (CTIME1 - address 0xE002 4018) bit description
Bit Symbol Description Reset
value
15:12 - Reserved, user software should not write ones to reserved bits. NA
The value read from a reserved bit is not defined.
27:16 Year Year value in the range of 0 to 4095. NA
31:28 - Reserved, user software should not write ones to reserved bits. NA
The value read from a reserved bit is not defined.

17.4.11 Consolidated Time register 2 (CTIME2 - 0xE002 401C)

The Consolidate Time register 2 contains just the Day of Year value.

Table 204: Consolidated Time register 2 (CTIME2 - address 0xE002 401C) bit description
Bit Symbol Description Reset
value
11:0 Day of Year Day of year value in the range of 1 to 365 (366 for leap years). NA
31:12 - Reserved, user software should not write ones to reserved bits. NA
The value read from a reserved bit is not defined.

17.4.12 Time counter group

The time value consists of the eight counters shown in Table 205 and Table 206. These
counters can be read or written at the locations shown in Table 206.

Table 205. Time counter relationships and values

Counter Size Enabled by Minimum value Maximum value
Second 6 Clk1 (see Figure 56) 0 59
Minute 6 Second 0 59
Hour 5 Minute 0 23
Day of Month 5 Hour 1 28, 29, 30 or 31
Day of Week 3 Hour 0 6
Day of Year 9 Hour 1 365 or 366 (for leap year)
Month 4 Day of Month 1 12
Year 12 Month or day of Year 0 4095

Table 206. Time counter registers

Name Size Description Access Address
SEC 6 Seconds value in the range of 0 to 59 R/W 0xE002 4020
MIN 6 Minutes value in the range of 0 to 59 R/W 0xE002 4024
HOUR 5 Hours value in the range of 0 to 23 R/W 0xE002 4028
DOM 5 Day of month value in the range of 1 to 28, 29, 30, R/W 0xE002 402C
or 31 (depending on the month and whether it is a
leap year).[1]
DOW 3 Day of week value in the range of 0 to 6[1] R/W 0xE002 4030

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Table 206. Time counter registers

Name Size Description Access Address
DOY 9 Day of year value in the range of 1 to 365 (366 for R/W 0xE002 4034
leap years)[1]
MONTH 4 Month value in the range of 1 to 12 R/W 0xE002 4038
YEAR 12 Year value in the range of 0 to 4095 R/W 0xE002 403C

[1] These values are simply incremented at the appropriate intervals and reset at the defined overflow point.
They are not calculated and must be correctly initialized in order to be meaningful.

17.4.13 Leap year calculation

The RTC does a simple bit comparison to see if the two lowest order bits of the year
counter are zero. If true, then the RTC considers that year a leap year. The RTC considers
all years evenly divisible by 4 as leap years. This algorithm is accurate from the year 1901
through the year 2099, but fails for the year 2100, which is not a leap year. The only effect
of leap year on the RTC is to alter the length of the month of February for the month, day
of month, and year counters.

17.4.14 Alarm register group

The alarm registers are shown in Table 207. The values in these registers are compared
with the time counters. If all the unmasked (See Section 17.4.7 “Alarm Mask Register
(AMR - 0xE002 4010)” on page 222) alarm registers match their corresponding time
counters then an interrupt is generated. The interrupt is cleared when a one is written to
bit one of the Interrupt Location Register (ILR[1]).

Table 207. Alarm registers

Name Size Description Access Address
ALSEC 6 Alarm value for Seconds R/W 0xE002 4060
ALMIN 6 Alarm value for Minutes R/W 0xE002 4064
ALHOUR 5 Alarm value for Hours R/W 0xE002 4068
ALDOM 5 Alarm value for Day of Month R/W 0xE002 406C
ALDOW 3 Alarm value for Day of Week R/W 0xE002 4070
ALDOY 9 Alarm value for Day of Year R/W 0xE002 4074
ALMON 4 Alarm value for Months R/W 0xE002 4078
ALYEAR 12 Alarm value for Years R/W 0xE002 407C

17.5 RTC usage notes

The VBAT pin must be connected to a voltage source supplying at least 1.8V all the time.
This means that in case no external battery is used the VBAT can be connected to VDD. If
the VBAT is left floating or tied to ground (VSS), the microcontroller will consume more
current especially in a low power (idle or power down) mode. In case the RTC is not used
at all, it is suggested that the RTCX1 pin (input to the RTC oscillator circuit) is tied to either
VSS or VDD, while the RTCX2 pin is left floating.

No provision is made in the LPC213x to retain RTC status upon the VBAT power loss, or
to maintain time incrementation if the clock source is lost, interrupted, or altered.

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Since the RTC operates using one of two available clocks (the APB clock (PCLK) or the
32 kHz signal coming from the RTCX1-2pins), any interruption of the selected clock will
cause the time to drift away from the time value it would have provided otherwise. The
variance could be to actual clock time if the RTC was initialized to that, or simply an error
in elapsed time since the RTC was activated.

While the signal from RTCX1-2 pins can be used to supply the RTC clock at anytime,
selecting the PCLK as the RTC clock and entering the Power-down mode will cause a
lapse in the time update. Also, feeding the RTC with the PCLK and altering this time base
during system operation (by reconfiguring the PLL, the APB divider, or the RTC prescaler)
will result in some form of accumulated time error. Accumulated time errors may occur in
case RTC clock source is switched between the PCLK to the RTCX pins, too.

Once the 32 kHz signal from RTCX1-2 pins is selected as a clock source, the RTC can
operate completely without the presence of the APB clock (PCLK). Therefore, power
sensitive applications (i.e. battery powered application) utilizing the RTC will reduce the
power consumption by using the signal from RTCX1-2 pins, and writing a 0 into the
PCRTC bit in the PCONP power control register (see Section 4.9 “Power control” on page
40).

When the RTC is running using the 32 kHz clock and the battery supply, the internal
registers can be read.However, internal registers cannot be written to without setting the
RTC power control bit PCRTC in the PCONP register to 1.

If the RTC is used to wake up from Power-down mode, the PLL will be disabled. If needed
in the application, the PLL must be enabled and connected again before it can be used as
a clock source after waking up from Power-down mode.

17.6 Reference clock divider (prescaler)

The reference clock divider (hereafter referred to as the prescaler) allows generation of a
32.768 kHz reference clock from any peripheral clock frequency greater than or equal to
65.536 kHz (2 × 32.768 kHz). This permits the RTC to always run at the proper rate
regardless of the peripheral clock rate. Basically, the Prescaler divides the peripheral
clock (PCLK) by a value which contains both an integer portion and a fractional portion.
The result is not a continuous output at a constant frequency, some clock periods will be
one PCLK longer than others. However, the overall result can always be 32,768 counts
per second.

The reference clock divider consists of a 13-bit integer counter and a 15-bit fractional
counter. The reasons for these counter sizes are as follows:

1. For frequencies that are expected to be supported by the LPC213x, a 13-bit integer
counter is required. This can be calculated as 160 MHz divided by 32,768 minus
1 = 4881 with a remainder of 26,624. Thirteen bits are needed to hold the value 4881,
but actually supports frequencies up to 268.4 MHz (32,768 × 8192).
2. The remainder value could be as large as 32,767, which requires 15 bits.

Table 208. Reference clock divider registers

Name Size Description Access Address
PREINT 13 Prescale Value, integer portion R/W 0xE002 4080
PREFRAC 15 Prescale Value, fractional portion R/W 0xE002 4084

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17.6.1 Prescaler Integer register (PREINT - 0xE002 4080)

This is the integer portion of the prescale value, calculated as:

PREINT = int (PCLK / 32768) − 1. The value of PREINT must be greater than or equal to
1.

Table 209: Prescaler Integer register (PREINT - address 0xE002 4080) bit description
Bit Symbol Description Reset
value
12:0 Prescaler Integer Contains the integer portion of the RTC prescaler value. 0
15:13 - Reserved, user software should not write ones to reserved NA
bits. The value read from a reserved bit is not defined.

17.6.2 Prescaler Fraction register (PREFRAC - 0xE002 4084)

This is the fractional portion of the prescale value, and may be calculated as:

PREFRAC = PCLK − ((PREINT + 1) × 32768).

Table 210: Prescaler Integer register (PREFRAC - address 0xE002 4084) bit description
Bit Symbol Description Reset
value
14:0 Prescaler Contains the integer portion of the RTC prescaler value. 0
Fraction
15 - Reserved, user software should not write ones to reserved NA
bits. The value read from a reserved bit is not defined.

17.6.3 Example of prescaler usage

In a simplistic case, the PCLK frequency is 65.537 kHz. So:

PREINT = int (PCLK / 32768) − 1 = 1 and

PREFRAC = PCLK - ([PREINT + 1] × 32768) = 1

With this prescaler setting, exactly 32,768 clocks per second will be provided to the RTC
by counting 2 PCLKs 32,767 times, and 3 PCLKs once.

In a more realistic case, the PCLK frequency is 10 MHz. Then,

PREINT = int (PCLK / 32768) − 1 = 304 and

PREFRAC = PCLK − ([PREINT + 1] × 32768) = 5,760.

In this case, 5,760 of the prescaler output clocks will be 306 (305 + 1) PCLKs long, the
rest will be 305 PCLKs long.

In a similar manner, any PCLK rate greater than 65.536 kHz (as long as it is an even
number of cycles per second) may be turned into a 32 kHz reference clock for the RTC.
The only caveat is that if PREFRAC does not contain a zero, then not all of the 32,768 per
second clocks are of the same length. Some of the clocks are one PCLK longer than
others. While the longer pulses are distributed as evenly as possible among the remaining
pulses, this jitter could possibly be of concern in an application that wishes to observe the
contents of the Clock Tick Counter (CTC) directly(Section 17.4.4 “Clock Tick Counter
Register (CTCR - 0xE002 4004)” on page 221).

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PCLK
to clock tick counter (APB clock)

CLK

CLK UNDERFLOW 15 BIT FRACTION COUNTER

13 BIT INTEGER COUNTER
(DOWN COUNTER)
RELOAD
15

COMBINATORIAL LOGIC
13 extend
reload

13 BIT RELOAD INTEGER 15 BIT FRACTION REGISTER

13 15
APB bus

Fig 57. RTC prescaler block diagram

17.6.4 Prescaler operation

The Prescaler block labelled Combination Logic in Figure 57 determines when the
decrement of the 13-bit PREINT counter is extended by one PCLK. In order to both insert
the correct number of longer cycles, and to distribute them evenly, the combinatorial Logic
associates each bit in PREFRAC with a combination in the 15-bit Fraction Counter. These
associations are shown in the following Table 211.

For example, if PREFRAC bit 14 is a one (representing the fraction 1/2), then half of the
cycles counted by the 13-bit counter need to be longer. When there is a 1 in the LSB of
the Fraction Counter, the logic causes every alternate count (whenever the LSB of the
Fraction Counter=1) to be extended by one PCLK, evenly distributing the pulse widths.
Similarly, a one in PREFRAC bit 13 (representing the fraction 1/4) will cause every fourth
cycle (whenever the two LSBs of the Fraction Counter=10) counted by the 13-bit counter
to be longer.

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Table 211. Prescaler cases where the Integer Counter reload value is incremented
Fraction Counter PREFRAC Bit
14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
--- ---- ---- ---1 1 - - - - - - - - - - - - - -
--- ---- ---- --10 - 1 - - - - - - - - - - - - -
--- ---- ---- -100 - - 1 - - - - - - - - - - - -
--- ---- ---- 1000 - - - 1 - - - - - - - - - - -
--- ---- ---1 0000 - - - - 1 - - - - - - - - - -
--- ---- --10 0000 - - - - - 1 - - - - - - - - -
--- ---- -100 0000 - - - - - - 1 - - - - - - - -
--- ---- 1000 0000 - - - - - - - 1 - - - - - - -
--- ---1 0000 0000 - - - - - - - - 1 - - - - - -
--- --10 0000 0000 - - - - - - - - - 1 - - - - -
--- -100 0000 0000 - - - - - - - - - - 1 - - - -
--- 1000 0000 0000 - - - - - - - - - - - 1 - - -
--1 0000 0000 0000 - - - - - - - - - - - - 1 - -
-10 0000 0000 0000 - - - - - - - - - - - - - 1 -
100 0000 0000 0000 - - - - - - - - - - - - - - 1

17.7 RTC external 32 kHz oscillator component selection

The RTC external oscillator circuit is shown in Figure 58. Since the feedback resistance is
integrated on chip, only a crystal, the capacitances CX1 and CX2 need to be connected
externally to the microcontroller.

LPC213x

RTCX1 RTCX2

32 kHz
CX1 CX2
Xtal

Fig 58. RTC 32kHz crystal oscillator circuit

Table 212 gives the crystal parameters that should be used. CL is the typical load
capacitance of the crystal and is usually specified by the crystal manufacturer. The actual
CL influences oscillation frequency. When using a crystal that is manufactured for a
UM10120 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved.

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different load capacitance, the circuit will oscillate at a slightly different frequency
(depending on the quality of the crystal) compared to the specified one. Therefore for an
accurate time reference it is advised to use the load capacitors as specified in Table 212
that belong to a specific CL. The value of external capacitances CX1 and CX2 specified in
this table are calculated from the internal parasitic capacitances and the CL. Parasitics
from PCB and package are not taken into account.

Table 212. Recommended values for the RTC external 32 kHz oscillator CX1/X2 components
Crystal load capacitance Maximum crystal series External load capacitors CX1, CX2
CL resistance RS
11 pF < 100 kΩ 18 pF, 18 pF
13 pF < 100 kΩ 22 pF, 22 pF
15 pF < 100 kΩ 27 pF, 27 pF

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18.1 Features
• 10 bit successive approximation analog to digital converter (one in LPC2131,
LPC2132, LPC2131/01, and LPC2132/01 and two in other LPC213x devices).
• Input multiplexing among 8 pins (ADC0 and ADC1).
• Power-down mode.
• Measurement range 0 V to VREF (typically 3 V; not to exceed VDDA voltage level).
• 10 bit conversion time ≥ 2.44 μs.
• Burst conversion mode for single or multiple inputs.
• Optional conversion on transition on input pin or Timer Match signal.
• Global Start command for both converters (LPC2134/6/8 and matching /01 devices).

18.1.1 Enhancements introduced with LPC213x/01 devices

Dedicated result register for every analog input reduces interrupt overhead.

18.2 Description
Basic clocking for the A/D converters is provided by the APB clock. A programmable
divider is included in each converter, to scale this clock to the 4.5 MHz (max) clock
needed by the successive approximation process. A fully accurate conversion requires 11
of these clocks.

18.3 Pin description

Table 213 gives a brief summary of each of ADC related pins.

Table 213. ADC pin description

Pin Type Description
AD0.7:0 & Input Analog Inputs. The ADC cell can measure the voltage on any of these input signals.
AD1.7:0 Note: if the ADC is used, signal levels on analog input pins must not be above the
(LPC2134/6/8 and level of V3A at any time. Otherwise, A/D converter readings will be invalid. If the A/D
matching /01 parts) converter is not used in an application then the pins associated with A/D inputs can be
used as 5 V tolerant digital IO pins.
Warning: while the ADC pins are specified as 5 V tolerant (see Section 5.2 “Pin
description for LPC213x” on page 51), the analog multiplexing in the ADC block is not.
More than 3.3 V (VDDA) should not be applied to any pin that is selected as an ADC
input, or the ADC reading will be incorrect. If for example AD0.0 and AD0.1 are used
as the ADC0 inputs and voltage on AD0.0 = 4.5 V while AD0.1 = 2.5 V, an excessive
voltage on the AD0.0 can cause an incorrect reading of the AD0.1, although the AD0.1
input voltage is within the right range.
VREF Reference Voltage Reference. This pin provides a voltage reference level for the A/D
converter(s).
VDDA, VSSA Power Analog Power and Ground. These should be nominally the same voltages as VDD
and VSS, but should be isolated to minimize noise and error.

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18.4 Register description

The A/D Converter registers are shown in Table 214.

Remark: ADC1 is available on parts LPC2134/36/38 and LPC2134/36/38/01 only.

Table 214. ADC registers

Generic Description Access Reset AD0 AD1
Name value[1] Address Address
& Name & Name
ADCR A/D Control Register. The ADCR register must be R/W 0x0000 0001 0xE003 4000 0xE006 0000
written to select the operating mode before A/D AD0CR AD1CR
conversion can occur.
ADGDR A/D Global Data Register. This register contains the R/W NA 0xE003 4004 0xE006 0004
ADC’s DONE bit and the result of the most recent A/D AD0GDR AD1GDR
conversion.
ADSTAT A/D Status Register. This register contains DONE and RO 0x0000 0000 0xE003 4030 0xE006 0030
[2] OVERRUN flags for all of the A/D channels, as well as AD0STAT AD1STAT
the A/D interrupt flag.
ADGSR A/D Global Start Register. This address can be written WO 0x00 0xE003 4008
(in the AD0 address range) to start conversions in both ADGSR
A/D converters simultaneously.
ADINTEN A/D Interrupt Enable Register. This register contains R/W 0x0000 0100 0xE003 400C 0xE006 000C
enable bits that allow the DONE flag of each A/D AD0INTEN AD1INTEN
channel to be included or excluded from contributing to
the generation of an A/D interrupt.
ADDR0[2] A/D Channel 0 Data Register. This register contains the RO NA 0xE003 4010 0xE006 0010
result of the most recent conversion completed on AD0DR0 AD1DR0
channel 0.
ADDR1[2] A/D Channel 1 Data Register. This register contains the RO NA 0xE003 4014 0xE006 0014
result of the most recent conversion completed on AD0DR1 AD1DR1
channel 1.
ADDR2[2] A/D Channel 2 Data Register. This register contains the RO NA 0xE003 4018 0xE006 0018
result of the most recent conversion completed on AD0DR2 AD1DR2
channel 2.
ADDR3[2] A/D Channel 3 Data Register. This register contains the RO NA 0xE003 401C 0xE006 001C
result of the most recent conversion completed on AD0DR3 AD1DR3
channel 3.
ADDR4[2] A/D Channel 4 Data Register. This register contains the RO NA 0xE003 4020 0xE006 0020
result of the most recent conversion completed on AD0DR4 AD1DR4
channel 4.
ADDR5[2] A/D Channel 5 Data Register. This register contains the RO NA 0xE003 4024 0xE006 0024
result of the most recent conversion completed on AD0DR5 AD1DR5
channel 5.
ADDR6[2] A/D Channel 6 Data Register. This register contains the RO NA 0xE003 4028 0xE006 0028
result of the most recent conversion completed on AD0DR6 AD1DR6
channel 6.
ADDR7[2] A/D Channel 7 Data Register. This register contains the RO NA 0xE003 402C 0xE006 002C
result of the most recent conversion completed on AD0DR7 AD1DR7
channel 7.

[1] Reset value reflects the data stored in used bits only. It does not include reserved bits content.
[2] Available in LPC213x/01 only.
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18.4.1 A/D Control Register (AD0CR - 0xE003 4000 and AD1CR -

0xE006 0000)
Table 215: A/D Control Register (AD0CR - address 0xE003 4000 and AD1CR - address 0xE006 0000) bit description
Bit Symbol Value Description Reset
value
7:0 SEL Selects which of the AD0.7:0/AD1.7:0 pins is (are) to be sampled and converted. For 0x01
AD0, bit 0 selects Pin AD0.0, and bit 7 selects pin AD0.7. In software-controlled mode,
only one of these bits should be 1. In hardware scan mode, any value containing 1 to 8
ones. All zeroes is equivalent to 0x01.
15:8 CLKDIV The APB clock (PCLK) is divided by (this value plus one) to produce the clock for the 0
A/D converter, which should be less than or equal to 4.5 MHz. Typically, software should
program the smallest value in this field that yields a clock of 4.5 MHz or slightly less, but
in certain cases (such as a high-impedance analog source) a slower clock may be
desirable.
16 BURST 1 The AD converter does repeated conversions at the rate selected by the CLKS field, 0
scanning (if necessary) through the pins selected by 1s in the SEL field. The first
conversion after the start corresponds to the least-significant 1 in the SEL field, then
higher numbered 1-bits (pins) if applicable. Repeated conversions can be terminated by
clearing this bit, but the conversion that’s in progress when this bit is cleared will be
completed.
Important: START bits must be 000 when BURST = 1 or conversions will not start.
0 Conversions are software controlled and require 11 clocks.
19:17 CLKS This field selects the number of clocks used for each conversion in Burst mode, and the 000
number of bits of accuracy of the result in the RESULT bits of ADDR, between 11 clocks
(10 bits) and 4 clocks (3 bits).
000 11 clocks / 10 bits
001 10 clocks / 9bits
010 9 clocks / 8 bits
011 8 clocks / 7 bits
100 7 clocks / 6 bits
101 6 clocks / 5 bits
110 5 clocks / 4 bits
111 4 clocks / 3 bits
20 - Reserved, user software should not write ones to reserved bits. The value read from a NA
reserved bit is not defined.
21 PDN 1 The A/D converter is operational. 0
0 The A/D converter is in power-down mode.
23:22 - Reserved, user software should not write ones to reserved bits. The value read from a NA
reserved bit is not defined.

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Table 215: A/D Control Register (AD0CR - address 0xE003 4000 and AD1CR - address 0xE006 0000) bit description
Bit Symbol Value Description Reset
value
26:24 START When the BURST bit is 0, these bits control whether and when an A/D conversion is 0
started:
000 No start (this value should be used when clearing PDN to 0).
001 Start conversion now.
010 Start conversion when the edge selected by bit 27 occurs on
P0.16/EINT0/MAT0.2/CAP0.2 pin[1].
011 Start conversion when the edge selected by bit 27 occurs on
P0.22/AD1.7/CAP0.0/MAT0.0 pin[1].
100 Start conversion when the edge selected by bit 27 occurs on MAT0.1[1].
101 Start conversion when the edge selected by bit 27 occurs on MAT0.3[1].
110 Start conversion when the edge selected by bit 27 occurs on MAT1.0[1].
111 Start conversion when the edge selected by bit 27 occurs on MAT1.1[1].
27 EDGE This bit is significant only when the START field contains 010-111. In these cases: 0
1 Start conversion on a falling edge on the selected CAP/MAT signal.
0 Start conversion on a rising edge on the selected CAP/MAT signal.
31:28 - Reserved, user software should not write ones to reserved bits. The value read from a NA
reserved bit is not defined.

[1] MATx.y output does not need to selected in a PINSEL register at all. It is important though that the right external match control is
selected in the Timer0/1 External Match Register.

18.4.2 A/D Global Data Register (AD0GDR - 0xE003 4004 and AD1GDR -
0xE006 0004)
Table 216: A/D Global Data Register (AD0GDR - address 0xE003 4004 and AD1GDR - address 0xE006 0004) bit
description
Bit Symbol Description Reset
value
5:0 - Reserved, user software should not write ones to reserved bits. The value read from NA
a reserved bit is not defined.
15:6 RESULT When DONE is 1, this field contains a binary fraction representing the voltage on NA
the AD0 or AD1 pin selected by the SEL field, divided by the voltage on the VDDA
pin (V/VREF). Zero in the field indicates that the voltage on the AD0 or AD1 pin was
less than, equal to, or close to that on VSSA, while 0x3FF indicates that the voltage
on AD0/1 was close to, equal to, or greater than that on VREF.
23:16 - Reserved, user software should not write ones to reserved bits. The value read from NA
a reserved bit is not defined.
26:24 CHN These bits contain the channel from which the RESULT bits were converted (e.g. NA
000 identifies channel 0, 001 channel 1...).
29:27 - Reserved, user software should not write ones to reserved bits. The value read from NA
a reserved bit is not defined.
30 OVERUN This bit is 1 in burst mode if the results of one or more conversions was (were) lost 0
and overwritten before the conversion that produced the result in the RESULT bits.
This bit is cleared by reading this register.
31 DONE This bit is set to 1 when an A/D conversion completes. It is cleared when this 0
register is read and when the ADCR is written. If the ADCR is written while a
conversion is still in progress, this bit is set and a new conversion is started.

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18.4.3 A/D Global Start Register (ADGSR - 0xE003 4008)

Software can write this register to simultaneously initiate conversions on both A/D
controllers. This register is available in LPC2134/6/8 and matching /01 devices only.

Table 217: A/D Global Start Register (ADGSR - address 0xE003 4008) bit description
Bit Symbol Value Description Reset
value
15:0 - Reserved, user software should not write ones to reserved bits. The value read from a NA
reserved bit is not defined.
16 BURST 1 The AD converters do repeated conversions at the rate selected by their CLKS fields, 0
scanning (if necessary) through the pins selected by 1s in their SEL field. The first
conversion after the start corresponds to the least-significant 1 in the SEL field, then
higher numbered 1-bits (pins) if applicable. Repeated conversions can be terminated by
clearing this bit, but the conversion that’s in progress when this bit is cleared will be
completed.
Important: START bits must be 000 when BURST = 1 or conversions will not start.
0 Conversions are software controlled and require 11 clocks.
23:17 - Reserved, user software should not write ones to reserved bits. The value read from a NA
reserved bit is not defined.
26:24 START When the BURST bit is 0, these bits control whether and when an A/D conversion is 0
started:
000 No start (this value should be used when clearing PDN to 0).
001 Start conversion now.
010 Start conversion when the edge selected by bit 27 occurs on
P0.16/EINT0/MAT0.2/CAP0.2 pin.
011 Start conversion when the edge selected by bit 27 occurs on
P0.22/AD1.7/CAP0.0/MAT0.0 pin.
100 Start conversion when the edge selected by bit 27 occurs on MAT0.1.
101 Start conversion when the edge selected by bit 27 occurs on MAT0.3.
110 Start conversion when the edge selected by bit 27 occurs on MAT1.0.
111 Start conversion when the edge selected by bit 27 occurs on MAT1.1.
27 EDGE This bit is significant only when the START field contains 010-111. In these cases: 0
1 Start conversion on a falling edge on the selected CAP/MAT signal.
0 Start conversion on a rising edge on the selected CAP/MAT signal.
31:28 - Reserved, user software should not write ones to reserved bits. The value read from a NA
reserved bit is not defined.

18.4.4 A/D Status Register (ADSTAT, ADC0: AD0STAT - 0xE003 4030 and
ADC1: AD1STAT - 0xE006 0030)
This register is available in LPC213x/01 devices only.

The A/D Status register allows checking the status of all A/D channels simultaneously.
The DONE and OVERRUN flags appearing in the ADDRn register for each A/D channel
are mirrored in ADSTAT. The interrupt flag (the logical OR of all DONE flags) is also found
in ADSTAT.

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Table 218: A/D Status Register (ADSTAT, ADC0: AD0STAT - address 0xE003 4030 and ADC1: AD1STAT - address
0xE006 0030) bit description
Bit Symbol Description Reset
value
0 DONE0 This bit mirrors the DONE status flag from the result register for A/D channel 0. 0
1 DONE1 This bit mirrors the DONE status flag from the result register for A/D channel 1. 0
2 DONE2 This bit mirrors the DONE status flag from the result register for A/D channel 2. 0
3 DONE3 This bit mirrors the DONE status flag from the result register for A/D channel 3. 0
4 DONE4 This bit mirrors the DONE status flag from the result register for A/D channel 4. 0
5 DONE5 This bit mirrors the DONE status flag from the result register for A/D channel 5. 0
6 DONE6 This bit mirrors the DONE status flag from the result register for A/D channel 6. 0
7 DONE7 This bit mirrors the DONE status flag from the result register for A/D channel 7. 0
8 OVERRUN0 This bit mirrors the OVERRRUN status flag from the result register for A/D channel 0. 0
9 OVERRUN1 This bit mirrors the OVERRRUN status flag from the result register for A/D channel 1. 0
10 OVERRUN2 This bit mirrors the OVERRRUN status flag from the result register for A/D channel 2. 0
11 OVERRUN3 This bit mirrors the OVERRRUN status flag from the result register for A/D channel 3. 0
12 OVERRUN4 This bit mirrors the OVERRRUN status flag from the result register for A/D channel 4. 0
13 OVERRUN5 This bit mirrors the OVERRRUN status flag from the result register for A/D channel 5. 0
14 OVERRUN6 This bit mirrors the OVERRRUN status flag from the result register for A/D channel 6. 0
15 OVERRUN7 This bit mirrors the OVERRRUN status flag from the result register for A/D channel 7. 0
16 ADINT This bit is the A/D interrupt flag. It is one when any of the individual A/D channel Done 0
flags is asserted and enabled to contribute to the A/D interrupt via the ADINTEN register.
31:17 - Reserved, user software should not write ones to reserved bits. The value read from a NA
reserved bit is not defined.

18.4.5 A/D Interrupt Enable Register (ADINTEN, ADC0: AD0INTEN -

0xE003 400C and ADC1: AD1INTEN - 0xE006 000C)
This register is available in LPC213x/01 devices only.

This register allows control over which A/D channels generate an interrupt when a
conversion is complete. For example, it may be desirable to use some A/D channels to
monitor sensors by continuously performing conversions on them. The most recent
results are read by the application program whenever they are needed. In this case, an
interrupt is not desirable at the end of each conversion for some A/D channels.

Table 219: A/D Status Register (ADSTAT, ADC0: AD0STAT - address 0xE003 4004 and ADC1: AD1STAT - address
0xE006 0004) bit description
Bit Symbol Value Description Reset
value
0 ADINTEN0 0 Completion of a conversion on ADC channel 0 will not generate an interrupt. 0
1 Completion of a conversion on ADC channel 0 will generate an interrupt.
1 ADINTEN1 0 Completion of a conversion on ADC channel 1 will not generate an interrupt. 0
1 Completion of a conversion on ADC channel 1 will generate an interrupt.
2 ADINTEN2 0 Completion of a conversion on ADC channel 2 will not generate an interrupt. 0
1 Completion of a conversion on ADC channel 2 will generate an interrupt.

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Table 219: A/D Status Register (ADSTAT, ADC0: AD0STAT - address 0xE003 4004 and ADC1: AD1STAT - address
0xE006 0004) bit description
Bit Symbol Value Description Reset
value
3 ADINTEN3 0 Completion of a conversion on ADC channel 3 will not generate an interrupt. 0
1 Completion of a conversion on ADC channel 3 will generate an interrupt.
4 ADINTEN4 0 Completion of a conversion on ADC channel 4 will not generate an interrupt. 0
1 Completion of a conversion on ADC channel 4 will generate an interrupt.
5 ADINTEN5 0 Completion of a conversion on ADC channel 5 will not generate an interrupt. 0
1 Completion of a conversion on ADC channel 5 will generate an interrupt.
6 ADINTEN6 0 Completion of a conversion on ADC channel 6 will not generate an interrupt. 0
1 Completion of a conversion on ADC channel 6 will generate an interrupt.
7 ADINTEN1 0 Completion of a conversion on ADC channel 7 will not generate an interrupt. 0
1 Completion of a conversion on ADC channel 7 will generate an interrupt.
8 ADGINTEN 0 Only the individual ADC channels enabled by ADINTEN7:0 will generate 1
interrupts.
1 Only the global DONE flag in ADDR is enabled to generate an interrupt.
31:17 - Reserved, user software should not write ones to reserved bits. The value NA
read from a reserved bit is not defined.

18.4.6 A/D Data Registers (ADDR0 to ADDR7, ADC0: AD0DR0 to AD0DR7 -

0xE003 4010 to 0xE003 402C and ADC1: AD1DR0 to AD1DR7-
0xE006 0010 to 0xE006 402C)
These registers are available in LPC213x/01 devices only.

The A/D Data Register hold the result when an A/D conversion is complete, and also
include the flags that indicate when a conversion has been completed and when a
conversion overrun has occurred.

Table 220: A/D Data Registers (ADDR0 to ADDR7, ADC0: AD0DR0 to AD0DR7 - 0xE003 4010 to 0xE003 402C and
ADC1: AD1DR0 to AD1DR7- 0xE006 0010 to 0xE006 402C) bit description
Bit Symbol Description Reset
value
5:0 - Reserved, user software should not write ones to reserved bits. The value read from a NA
reserved bit is not defined.
15:6 RESULT When DONE is 1, this field contains a binary fraction representing the voltage on the AIN pin, NA
divided by the voltage on the VREF pin (V/VREF). Zero in the field indicates that the voltage on
the AIN pin was less than, equal to, or close to that on VSSA, while 0x3FF indicates that the
voltage on AIN was close to, equal to, or greater than that on VREF.
29:16 - Reserved, user software should not write ones to reserved bits. The value read from a NA
reserved bit is not defined.
30 OVERRUN This bit is 1 in burst mode if the results of one or more conversions was (were) lost and
overwritten before the conversion that produced the result in the RESULT bits.This bit is
cleared by reading this register.
31 DONE This bit is set to 1 when an A/D conversion completes. It is cleared when this register is read. NA

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Chapter 18: LPC213x ADC

18.5 Operation

18.5.1 Hardware-triggered conversion

If the BURST bit in the ADCR is 0 and the START field contains 010-111, the ADC will
start a conversion when a transition occurs on a selected pin or Timer Match signal. The
choices include conversion on a specified edge of any of 4 Match signals, or conversion
on a specified edge of either of 2 Capture/Match pins. The pin state from the selected pad
or the selected Match signal, XORed with ADCR bit 27, is used in the edge detection
logic.

18.5.2 Interrupts
An interrupt request is asserted to the Vectored Interrupt Controller (VIC) when the DONE
bit is 1. Software can use the Interrupt Enable bit for the A/D Converter in the VIC to
control whether this assertion results in an interrupt. DONE is negated when the ADDR is
read.

18.5.3 Accuracy vs. digital receiver

The AD0 or AD1 function must be selected in corresponding Pin Select register (see "Pin
Connect Block") in order to get accurate voltage readings on the monitored pin. For a pin
hosting an ADC input, it is not possible to have a digital function selected and yet get valid
ADC readings. An inside circuit disconnects ADC hardware from the associated pin
whenever a digital function is selected on that pin.

18.5.4 Suggested ADC interface

It is suggested that RVSI is kept below 40 kΩ.

LPC2XXX

20 kΩ Rvsi
ADx.y
ADx.ySAMPLE

3 pF 5 pF

VEXT

VSS

Fig 59. Suggested ADC interface

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Chapter 19: LPC213x DAC
Rev. 3 — 4 October 2010 User manual

19.1 Features
Remark: This peripheral is available in LPC2132/4/6/8 and matching /01 devices.

• 10 bit digital to analog converter

• Resistor string architecture
• Buffered output
• Power-down mode
• Selectable speed vs. power

19.2 Pin description

Table 221 gives a brief summary of each of DAC related pins.

Table 221. DAC pin description

Pin Type Description
AOUT Output Analog Output. After the selected settling time after the DACR is
written with a new value, the voltage on this pin (with respect to
VSSA) is VALUE/1024 × VREF.
VREF Reference Voltage Reference. This pin provides a voltage reference level for
the D/A converter.
VDDA, VSSA Power Analog Power and Ground. These should be nominally the same
voltages as V3 and VSSD, but should be isolated to minimize noise
and error.

19.3 DAC Register (DACR - 0xE006 C000)

This read/write register includes the digital value to be converted to analog, and a bit that
trades off performance vs. power. Bits 5:0 are reserved for future, higher-resolution D/A
converters.

Table 222: DAC Register (DACR - address 0xE006 C000) bit description
Bit Symbol Value Description Reset
value
5:0 - Reserved, user software should not write ones to reserved NA
bits. The value read from a reserved bit is not defined.
15:6 VALUE After the selected settling time after this field is written with a 0
new VALUE, the voltage on the AOUT pin (with respect to VSSA)
is VALUE/1024 × VREF.
16 BIAS 0 The settling time of the DAC is 1 μs max, and the maximum 0
current is 700 μA.
1 The settling time of the DAC is 2.5 μs and the maximum
current is 350 μA.
31:17 - Reserved, user software should not write ones to reserved NA
bits. The value read from a reserved bit is not defined.

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19.4 Operation
Bits 19:18 of the PINSEL1 register (Section 6.4.2 “Pin function Select register 1 (PINSEL1
- 0xE002 C004)” on page 60) control whether the DAC is enabled and controlling the state
of pin P0.25/AD0.4/AOUT. When these bits are 10, the DAC is powered on and active.

The settling times noted in the description of the BIAS bit are valid for a capacitance load
on the AOUT pin not exceeding 100 pF. A load impedance value greater than that value will
cause settling time longer than the specified time.

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UM10120
Chapter 20: LPC213x Flash memory
Rev. 3 — 4 October 2010 User manual

20.1 Flash boot loader

The Boot Loader controls initial operation after reset, and also provides the means to
accomplish programming of the Flash memory. This could be initial programming of a
blank device, erasure and re-programming of a previously programmed device, or
programming of the Flash memory by the application program in a running system.

20.2 Features
• In-System Programming: In-System programming (ISP) is programming or
reprogramming the on-chip flash memory, using the boot loader software and a serial
port. This can be done when the part resides in the end-user board.
• In Application Programming: In-Application (IAP) programming is performing erase
and write operation on the on-chip flash memory, as directed by the end-user
application code.

20.3 Applications
The flash boot loader provides both In-System and In-Application programming interfaces
for programming the on-chip flash memory.

20.4 Description
The flash boot loader code is executed every time the part is powered on or reset. The
loader can execute the ISP command handler or the user application code. A LOW level
after reset at the P0.14 pin is considered as an external hardware request to start the ISP
command handler. Assuming that proper signal is present on XTAL1 pin when the rising
edge on RESET pin is generated, it may take up to 3 ms before P0.14 is sampled and the
decision on whether to continue with user code or ISP handler is made. If P0.14 is
sampled low and the watchdog overflow flag is set, the external hardware request to start
the ISP command handler is ignored. If there is no request for the ISP command handler
execution (P0.14 is sampled HIGH after reset), a search is made for a valid user program.
If a valid user program is found then the execution control is transferred to it. If a valid user
program is not found, the auto-baud routine is invoked.

Pin P0.14 that is used as hardware request for ISP requires special attention. Since P0.14
is in high impedance mode after reset, it is important that the user provides external
hardware (a pull-up resistor or other device) to put the pin in a defined state. Otherwise
unintended entry into ISP mode may occur.

20.4.1 Memory map after any reset

The boot block is 12 kB in size and resides in the top portion (starting from 0x0007 D000)
of the on-chip flash memory. After any reset the entire boot block is also mapped to the
top of the on-chip memory space i.e. the boot block is also visible in the memory region
starting from the address 0x7FFF D000. The flash boot loader is designed to run from this
UM10120 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved.

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memory area but both the ISP and IAP software use parts of the on-chip RAM. The RAM
usage is described later in this chapter. The interrupt vectors residing in the boot block of
the on-chip flash memory also become active after reset, i.e., the bottom 64 bytes of the
boot block are also visible in the memory region starting from the address 0x0000 0000.
The reset vector contains a jump instruction to the entry point of the flash boot loader
software.

2.0 GB 0x7FFF FFFF

12 kB BOOT BLOCK
RE-MAPPED FROM TOP OF FLASH MEMORY

2.0 GB - 12 kB (BOOT BLOCK INTERRUPT VECTORS) 0x7FFF D000

0x0007 FFFF
12 kB BOOT BLOCK
RE-MAPPED FROM TO HIGHER ADDRESS RANGE
0x0007 D000

ON-CHIP FLASH MEMORY

ACTIVE INTERRUPT VECTORS

FROM BOOT BLOCK
0.0 GB 0x0000 0000

Fig 60. Map of lower memory after reset

20.4.2 Criterion for valid user code

Criterion for valid user code: The reserved ARM interrupt vector location (0x0000 0014)
should contain the 2’s complement of the check-sum of the remaining interrupt vectors.
This causes the checksum of all of the vectors together to be 0. The boot loader code
disables the overlaying of the interrupt vectors from the boot block, then checksums the
interrupt vectors in sector 0 of the flash. If the signatures match then the execution control
is transferred to the user code by loading the program counter with 0x0000 0000. Hence
the user flash reset vector should contain a jump instruction to the entry point of the user
application code.

If the signature is not valid, the auto-baud routine synchronizes with the host via serial port
0. The host should send a ’?’ (0x3F) as a synchronization character and wait for a
response. The host side serial port settings should be 8 data bits, 1 stop bit and no parity.
The auto-baud routine measures the bit time of the received synchronization character in
terms of its own frequency and programs the baud rate generator of the serial port. It also
sends an ASCII string ("Synchronized<CR><LF>") to the Host. In response to this host
should send the same string ("Synchronized<CR><LF>"). The auto-baud routine looks at

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the received characters to verify synchronization. If synchronization is verified then

"OK<CR><LF>" string is sent to the host. Host should respond by sending the crystal
frequency (in kHz) at which the part is running. For example, if the part is running at 10
MHz , the response from the host should be "10000<CR><LF>". "OK<CR><LF>" string is
sent to the host after receiving the crystal frequency. If synchronization is not verified then
the auto-baud routine waits again for a synchronization character. For auto-baud to work
correctly, the crystal frequency should be greater than or equal to 10 MHz. The on-chip
PLL is not used by the boot code.

Once the crystal frequency is received the part is initialized and the ISP command handler
is invoked. For safety reasons an "Unlock" command is required before executing the
commands resulting in flash erase/write operations and the "Go" command. The rest of
the commands can be executed without the unlock command. The Unlock command is
required to be executed once per ISP session. The Unlock command is explained in
Section 20.8 “ISP commands” on page 250.

20.4.3 Communication protocol

All ISP commands should be sent as single ASCII strings. Strings should be terminated
with Carriage Return (CR) and/or Line Feed (LF) control characters. Extra <CR> and
<LF> characters are ignored. All ISP responses are sent as <CR><LF> terminated ASCII
strings. Data is sent and received in UU-encoded format.

20.4.4 ISP command format

"Command Parameter_0 Parameter_1 ... Parameter_n<CR><LF>" "Data" (Data only for
Write commands)

20.4.5 ISP response format

"Return_Code<CR><LF>Response_0<CR><LF>Response_1<CR><LF> ...
Response_n<CR><LF>" "Data" (Data only for Read commands)

20.4.6 ISP data format

The data stream is in UU-encode format. The UU-encode algorithm converts 3 bytes of
binary data in to 4 bytes of printable ASCII character set. It is more efficient than Hex
format which converts 1 byte of binary data in to 2 bytes of ASCII hex. The sender should
send the check-sum after transmitting 20 UU-encoded lines. The length of any
UU-encoded line should not exceed 61 characters (bytes) i.e. it can hold 45 data bytes.
The receiver should compare it with the check-sum of the received bytes. If the
check-sum matches then the receiver should respond with "OK<CR><LF>" to continue
further transmission. If the check-sum does not match the receiver should respond with
"RESEND<CR><LF>". In response the sender should retransmit the bytes.

A description of UU-encode is available at the website wotsit.org.

20.4.7 ISP flow control

A software XON/XOFF flow control scheme is used to prevent data loss due to buffer
overrun. When the data arrives rapidly, the ASCII control character DC3 (stop) is sent to
stop the flow of data. Data flow is resumed by sending the ASCII control character DC1
(start). The host should also support the same flow control scheme.

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20.4.8 ISP command abort

Commands can be aborted by sending the ASCII control character "ESC". This feature is
not documented as a command under "ISP Commands" section. Once the escape code is
received the ISP command handler waits for a new command.

20.4.9 Interrupts during ISP

The boot block interrupt vectors located in the boot block of the flash are active after any
reset.

20.4.10 Interrupts during IAP

The on-chip flash memory is not accessible during erase/write operations. When the user
application code starts executing the interrupt vectors from the user flash area are active.
The user should either disable interrupts, or ensure that user interrupt vectors are active in
RAM and that the interrupt handlers reside in RAM, before making a flash erase/write IAP
call. The IAP code does not use or disable interrupts.

20.4.11 RAM used by ISP command handler

ISP commands use on-chip RAM from 0x4000 0120 to 0x4000 01FF. The user could use
this area, but the contents may be lost upon reset. Flash programming commands use the
top 32 bytes of on-chip RAM. The stack is located at RAM top − 32. The maximum stack
usage is 256 bytes and it grows downwards.

20.4.12 RAM used by IAP command handler

Flash programming commands use the top 32 bytes of on-chip RAM. The maximum stack
usage in the user allocated stack space is 128 bytes and it grows downwards.

20.4.13 RAM used by RealMonitor

The RealMonitor uses on-chip RAM from 0x4000 0040 to 0x4000 011F. he user could use
this area if RealMonitor based debug is not required. The Flash boot loader does not
initialize the stack for RealMonitor.

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20.4.14 Boot process flowchart

RESET

INITIALIZE

CRP1/2/3 no
ENABLED?
ENABLE DEBUG
yes

yes A
WATCHDOG
FLAG SET?

no
yes
USER CODE
VALID?
CRP3 no
ENABLED?
no

yes EXECUTE INTERNAL

USER CODE

USER CODE no no boot from

VALID? UART

RUN AUTO-BAUD
yes

A
no AUTO-BAUD
SUCCESSFUL?

yes

RECEIVE CRYSTAL FREQUENCY

RUN UART ISP COMMAND HANDLER

Fig 61. Boot process flowchart

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20.5 Sector numbers

Some IAP and ISP commands operate on "sectors" and specify sector numbers. The
following table indicate the correspondence between sector numbers and memory
addresses for LPC213x devices containing 32, 64, 128, 256 and 512K bytes of Flash
respectively. IAP, ISP, and RealMonitor routines are located in the boot block. The boot
block is present at addresses 0x0007 D000 to 0x0007 FFFF in all devices. ISP and IAP
commands do not allow write/erase/go operation on the boot block. Because of the boot
block, the amount of Flash available for user code and data is 500 K bytes in "512K"
devices. On the other hand, in case of the LPC2131/2/4/6 microcontroller and matching
/01 devices all 32/64/128/256 K of Flash are available for user’s application.

Table 223. Flash sectors in LPC2131, LPC2132, LPC2134, LPC2136 and LPC2138
Sector Sector Address Range

256 kB: LPC2136

128 kB: LPC2134

512 kB: LPC2138

and LPC2131/01

and LPC2132/01

and LPC2134/01

and LPC2136/01

and LPC2138/01
32 kB: LPC2131

64 kB: LPC2132
Number Size [kB]

0 4 0X0000 0000 - 0X0000 0FFF + + + + +

1 4 0X0000 1000 - 0X0000 1FFF + + + + +
2 4 0X0000 2000 - 0X0000 2FFF + + + + +
3 4 0X0000 3000 - 0X0000 3FFF + + + + +
4 4 0X0000 4000 - 0X0000 4FFF + + + + +
5 4 0X0000 5000 - 0X0000 5FFF + + + + +
6 4 0X0000 6000 - 0X0000 6FFF + + + + +
7 4 0X0000 7000 - 0X0000 7FFF + + + + +
8 32 0x0000 8000 - 0X0000 FFFF + + + +
9 32 0x0001 0000 - 0X0001 7FFF + + +
10 (0x0A) 32 0x0001 8000 - 0X0001 FFFF + + +
11 (0x0B) 32 0x0002 0000 - 0X0002 7FFF + +
12 (0x0C) 32 0x0002 8000 - 0X0002 FFFF + +
13 (0x0D) 32 0x0003 0000 - 0X0003 7FFF + +
14 (0X0E) 32 0x0003 8000 - 0X0003 FFFF + +

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Table 223. Flash sectors in LPC2131, LPC2132, LPC2134, LPC2136 and LPC2138
Sector Sector Address Range

128 kB: LPC2134

256 kB: LPC2136

512 kB: LPC2138

and LPC2131/01

and LPC2132/01

and LPC2134/01

and LPC2136/01

and LPC2138/01
32 kB: LPC2131

64 kB: LPC2132
Number Size [kB]

15 (0x0F) 32 0x0004 0000 - 0X0004 7FFF +

16 (0x10) 32 0x0004 8000 - 0X0004 FFFF +
17 (0x11) 32 0x0005 0000 - 0X0005 7FFF +
18 (0x12) 32 0x0005 8000 - 0X0005 FFFF +
19 (0x13) 32 0x0006 0000 - 0X0006 7FFF +
20 (0x14) 32 0x0006 8000 - 0X0006 FFFF +
21 (0x15) 32 0x0007 0000 - 0X0007 7FFF +
22 (0x16) 4 0x0007 8000 - 0X0007 8FFF +
23 (0x17) 4 0x0007 9000 - 0X0007 9FFF +
24 (0x18) 4 0x0007 A000 - 0X0007 AFFF +
25 (0x19) 4 0x0007 B000 - 0X0007 BFFF +
26 (0x1A) 4 0x0007 C000 - 0X0007 CFFF +

20.6 Flash content protection mechanism

The LPC213x is equipped with the Error Correction Code (ECC) capable Flash memory.
The purpose of an error correction module is twofold. Firstly, it decodes data words read
from the memory into output data words. Secondly, it encodes data words to be written to
the memory. The error correction capability consists of single bit error correction with
Hamming code.

The operation of ECC is transparent to the running application. The ECC content itself is
stored in a flash memory not accessible by user’s code to either read from it or write into it
on its own. A byte of ECC corresponds to every consecutive 128 bits of the user
accessible Flash. Consequently, Flash bytes from 0x0000 0000 to 0x0000 000F are
protected by the first ECC byte, Flash bytes from 0x0000 0010 to 0x0000 001F are
protected by the second ECC byte, etc.

Whenever the CPU requests a read from user’s Flash, both 128 bits of raw data
containing the specified memory location and the matching ECC byte are evaluated. If the
ECC mechanism detects a single error in the fetched data, a correction will be applied
before data are provided to the CPU. When a write request into the user’s Flash is made,
write of user specified content is accompanied by a matching ECC value calculated and
stored in the ECC memory.

When a sector of user’s Flash memory is erased, corresponding ECC bytes are also
erased. Once an ECC byte is written, it can not be updated unless it is erased first.
Therefore, for the implemented ECC mechanism to perform properly, data must be written
into the Flash memory in groups of 16 bytes (or multiples of 4), aligned as described
above.

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20.7 Code Read Protection (CRP)

Code Read Protection is a mechanism that allows user to enable different levels of
security in the system so that access to the on-chip Flash and use of the ISP can be
restricted. When needed, CRP is invoked by programming a specific pattern in Flash
location at 0x0000 01FC. IAP commands are not affected by the code read protection.

Important: CRP is active/inactive once the device has gone through a power cycle.

Table 224. Code Read Protection levels

Name Pattern Description
programmed
in 0x000001FC
NO_I 0x4E69 7370 Prevents sampling of pin P0.14 for entering ISP mode. P0.14 is available
SP for other uses.
CRP1 0x12345678 Access to chip via the JTAG pins is disabled. This mode allows partial
Flash update using the following ISP commands and restrictions:
• Write to RAM command can not access RAM below 0x40000200
• Copy RAM to Flash command can not write to Sector 0
• Erase command can erase Sector 0 only when all sectors are
selected for erase
• Compare command is disabled
This mode is useful when CRP is required and Flash field updates are
needed but all sectors can not be erased. Since compare command is
disabled in case of partial updates the secondary loader should
implement checksum mechanism to verify the integrity of the Flash.
CRP2 0x87654321 Access to chip via the JTAG pins is disabled. The following ISP
commands are disabled:
• Read Memory
• Write to RAM
• Go
• Copy RAM to Flash
• Compare
When CRP2 is enabled the ISP erase command only allows erasure of
all user sectors.
CRP3 0x43218765 Access to chip via the JTAG pins is disabled. ISP entry by pulling P0.14
LOW is disabled if a valid user code is present in Flash sector 0.
This mode effectively disables ISP override using P0.14 pin. It is up to
the user’s application to provide Flash update mechanism using IAP
calls if necessary.
Caution: If CRP3 is selected, no future factory testing can be
performed on the device.

Table 225. Code Read Protection hardware/software interaction

CRP option User Code P0.14 pin at JTAG enabled enter ISP partial Flash
Valid reset mode update in ISP
mode
No No X Yes Yes Yes
No Yes High Yes No NA
No Yes Low Yes Yes Yes

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Table 225. Code Read Protection hardware/software interaction

CRP option User Code P0.14 pin at JTAG enabled enter ISP partial Flash
Valid reset mode update in ISP
mode
CRP1 Yes High No No NA
CRP1 Yes Low No Yes Yes
CRP2 Yes High No No NA
CRP2 Yes Low No Yes No
CRP3 Yes x No No NA
CRP1 No x No Yes Yes
CRP2 No x No Yes No
CRP3 No x No Yes No

In case a CRP mode is enabled and access to the chip is allowed via the ISP, an
unsupported or restricted ISP command will be terminated with return code
CODE_READ_PROTECTION_ENABLED.

20.7.1 Bootloader options

The levels of code read protection implemented depend on the boot loader code
version.The following options can be selected by the user in various revisions of the
bootloader code (see Table 226).

Table 226. Code read protection options for different bootloader revisions
Option 1 (CRP1) Option 2 (CRP2) Option 3 (CRP 3) Option NO_ISP
JTAG access is blocked. JTAG access is blocked. JTAG access is blocked.
Prevents sampling of
Supports partial flash updates. • ISP commands allowed: No ISP commands are allowed pin P0.14 for entering
• ISP commands allowed: Echo; Set Baud; Erase (all when P0.14 is pulled LOW and ISP mode. P0.14 is
Echo; Set Baud; Erase sectors only); Blank Check a valid user program is present available for other uses.
(except sector 0, must (fail returns value 0 at in flash sector 0. JTAG remains enabled
erase all to erase sector location 0); Prepare for flash
0); Blank Check (fail Sector; Unlock; Read Part erase/programming
returns value 0 at location ID; Read Boot code operation.
0); Prepare Sector; version.
Unlock; Read Part ID; • ISP commands not
Read Boot code version; allowed: Write to RAM;
Write to RAM (addresses Read Memory; Copy RAM
above 0x4000 0200); Copy to Flash; Go; Compare.
RAM to Flash (except
sector 0)
• ISP commands not
allowed: Write to RAM
below address 0x4000
0200; Read Memory; Copy
RAM to Flash (write to
sector 0); Erase sector 0;
Go; Compare.

Table 227 shows which code read protection options can be selected for any implemented
boot loader revision.

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Table 227. Bootloader revisions

Revision Pattern programmed @ location 0x1FC:
0x1234 5678 0x8765 4321 0x4321 8765 0x4E69 7370
2.13 option 1 option 2 option 3 option NO_ISP
2.12 option 1 option 2 option 3 -
2.0 to 2.11 - option 2 - -

20.8 ISP commands

The following commands are accepted by the ISP command handler. Detailed status
codes are supported for each command. The command handler sends the return code
INVALID_COMMAND when an undefined command is received. Commands and return
codes are in ASCII format.

CMD_SUCCESS is sent by ISP command handler only when received ISP command has
been completely executed and the new ISP command can be given by the host.
Exceptions from this rule are "Set Baud Rate", "Write to RAM", "Read Memory", and "Go"
commands.

Table 228. ISP command summary

ISP Command Usage Described in
Unlock U <Unlock Code> Table 229
Set Baud Rate B <Baud Rate> <stop bit> Table 230
Echo A <setting> Table 232
Write to RAM W <start address> <number of bytes> Table 233
Read Memory R <address> <number of bytes> Table 234
Prepare sector(s) for P <start sector number> <end sector number> Table 235
write operation
Copy RAM to Flash C <Flash address> <RAM address> <number of bytes> Table 236
Go G <address> <Mode> Table 237
Erase sector(s) E <start sector number> <end sector number> Table 238
Blank check sector(s) I <start sector number> <end sector number> Table 239
Read Part ID J Table 240
Read Boot code version K Table 242
Compare M <address1> <address2> <number of bytes> Table 243

20.8.1 Unlock <unlock code>

Table 229. ISP Unlock command
Command U
Input Unlock code: 2313010
Return Code CMD_SUCCESS |
INVALID_CODE |
PARAM_ERROR
Description This command is used to unlock flash Write, Erase, and Go commands.
Example "U 23130<CR><LF>" unlocks the flash Write/Erase & Go commands.

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20.8.2 Set Baud Rate <baud rate> <stop bit>

Table 230. ISP Set Baud Rate command
Command B
Input Baud Rate: 9600 | 19200 | 38400 | 57600 | 115200 | 230400
Stop bit: 1 | 2
Return Code CMD_SUCCESS |
INVALID_BAUD_RATE |
INVALID_STOP_BIT |
PARAM_ERROR
Description This command is used to change the baud rate. The new baud rate is effective
after the command handler sends the CMD_SUCCESS return code.
Example "B 57600 1<CR><LF>" sets the serial port to baud rate 57600 bps and 1 stop bit.

Table 231. Correlation between possible ISP baudrates and external crystal frequency (in
MHz)
ISP Baudrate .vs. 9600 19200 38400 57600 115200 230400
External Crystal Frequency
10.0000 + + +
11.0592 + + +
12.2880 + + +
14.7456 + + + + + +
15.3600 +
18.4320 + + +
19.6608 + + +
24.5760 + + +
25.0000 + + +

20.8.3 Echo <setting>

Table 232. ISP Echo command
Command A
Input Setting: ON = 1 | OFF = 0
Return Code CMD_SUCCESS |
PARAM_ERROR
Description The default setting for echo command is ON. When ON the ISP command handler
sends the received serial data back to the host.
Example "A 0<CR><LF>" turns echo off.

20.8.4 Write to RAM <start address> <number of bytes>

The host should send the data only after receiving the CMD_SUCCESS return code. The
host should send the check-sum after transmitting 20 UU-encoded lines. The checksum is
generated by adding raw data (before UU-encoding) bytes and is reset after transmitting
20 UU-encoded lines. The length of any UU-encoded line should not exceed 61
characters(bytes) i.e. it can hold 45 data bytes. When the data fits in less then 20
UU-encoded lines then the check-sum should be of the actual number of bytes sent. The

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ISP command handler compares it with the check-sum of the received bytes. If the
check-sum matches, the ISP command handler responds with "OK<CR><LF>" to
continue further transmission. If the check-sum does not match, the ISP command
handler responds with "RESEND<CR><LF>". In response the host should retransmit the
bytes.

Table 233. ISP Write to RAM command

Command W
Input Start Address: RAM address where data bytes are to be written. This address
should be a word boundary.
Number of Bytes: Number of bytes to be written. Count should be a multiple of 4
Return Code CMD_SUCCESS |
ADDR_ERROR (Address not on word boundary) |
ADDR_NOT_MAPPED |
COUNT_ERROR (Byte count is not multiple of 4) |
PARAM_ERROR |
CODE_READ_PROTECTION_ENABLED
Description This command is used to download data to RAM. Data should be in UU-encoded
format. This command is blocked when code read protection is enabled.
Example "W 1073742336 4<CR><LF>" writes 4 bytes of data to address 0x4000 0200.

20.8.5 Read memory <address> <no. of bytes>

The data stream is followed by the command success return code. The check-sum is sent
after transmitting 20 UU-encoded lines. The checksum is generated by adding raw data
(before UU-encoding) bytes and is reset after transmitting 20 UU-encoded lines. The
length of any UU-encoded line should not exceed 61 characters(bytes) i.e. it can hold 45
data bytes. When the data fits in less then 20 UU-encoded lines then the check-sum is of
actual number of bytes sent. The host should compare it with the checksum of the
received bytes. If the check-sum matches then the host should respond with
"OK<CR><LF>" to continue further transmission. If the check-sum does not match then
the host should respond with "RESEND<CR><LF>". In response the ISP command
handler sends the data again.

Table 234. ISP Read memory command

Command R
Input Start Address: Address from where data bytes are to be read. This address
should be a word boundary.
Number of Bytes: Number of bytes to be read. Count should be a multiple of 4.
Return Code CMD_SUCCESS followed by <actual data (UU-encoded)> |
ADDR_ERROR (Address not on word boundary) |
ADDR_NOT_MAPPED |
COUNT_ERROR (Byte count is not a multiple of 4) |
PARAM_ERROR |
CODE_READ_PROTECTION_ENABLED
Description This command is used to read data from RAM or Flash memory. This command is
blocked when code read protection is enabled.
Example "R 1073741824 4<CR><LF>" reads 4 bytes of data from address 0x4000 0000.

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20.8.6 Prepare sector(s) for write operation <start sector number> <end
sector number>
This command makes flash write/erase operation a two step process.

Table 235. ISP Prepare sector(s) for write operation command

Command P
Input Start Sector Number
End Sector Number: Should be greater than or equal to start sector number.
Return Code CMD_SUCCESS |
BUSY |
INVALID_SECTOR |
PARAM_ERROR
Description This command must be executed before executing "Copy RAM to Flash" or
"Erase Sector(s)" command. Successful execution of the "Copy RAM to Flash" or
"Erase Sector(s)" command causes relevant sectors to be protected again. The
boot block can not be prepared by this command. To prepare a single sector use
the same "Start" and "End" sector numbers.
Example "P 0 0<CR><LF>" prepares the flash sector 0.

20.8.7 Copy RAM to Flash <Flash address> <RAM address> <no of bytes>
Table 236. ISP Copy command
Command C
Input Flash Address(DST): Destination Flash address where data bytes are to be
written. The destination address should be a 256 byte boundary.
RAM Address(SRC): Source RAM address from where data bytes are to be read.
Number of Bytes: Number of bytes to be written. Should be 256 | 512 | 1024 |
4096.
Return Code CMD_SUCCESS |
SRC_ADDR_ERROR (Address not on word boundary) |
DST_ADDR_ERROR (Address not on correct boundary) |
SRC_ADDR_NOT_MAPPED |
DST_ADDR_NOT_MAPPED |
COUNT_ERROR (Byte count is not 256 | 512 | 1024 | 4096) |
SECTOR_NOT_PREPARED_FOR WRITE_OPERATION |
BUSY |
CMD_LOCKED |
PARAM_ERROR |
CODE_READ_PROTECTION_ENABLED
Description This command is used to program the flash memory. The "Prepare Sector(s) for
Write Operation" command should precede this command. The affected sectors are
automatically protected again once the copy command is successfully executed.
The boot block cannot be written by this command. This command is blocked when
code read protection is enabled.
Example "C 0 1073774592 512<CR><LF>" copies 512 bytes from the RAM address
0x4000 8000 to the flash address 0.

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20.8.8 Go <address> <mode>

Table 237. ISP Go command
Command G
Input Address: Flash or RAM address from which the code execution is to be started.
This address should be on a word boundary.
Mode: T (Execute program in Thumb Mode) | A (Execute program in ARM mode).
Return Code CMD_SUCCESS |
ADDR_ERROR |
ADDR_NOT_MAPPED |
CMD_LOCKED |
PARAM_ERROR |
CODE_READ_PROTECTION_ENABLED
Description This command is used to execute a program residing in RAM or Flash memory. It
may not be possible to return to the ISP command handler once this command is
successfully executed. This command is blocked when code read protection is
enabled.
Example "G 0 A<CR><LF>" branches to address 0x0000 0000 in ARM mode.

20.8.9 Erase sector(s) <start sector number> <end sector number>

Table 238. ISP Erase sector command
Command E
Input Start Sector Number
End Sector Number: Should be greater than or equal to start sector number.
Return Code CMD_SUCCESS |
BUSY |
INVALID_SECTOR |
SECTOR_NOT_PREPARED_FOR_WRITE_OPERATION |
CMD_LOCKED |
PARAM_ERROR |
CODE_READ_PROTECTION_ENABLED
Description This command is used to erase one or more sector(s) of on-chip Flash memory.
The boot block can not be erased using this command. This command only allows
erasure of all user sectors when the code read protection is enabled.
Example "E 2 3<CR><LF>" erases the flash sectors 2 and 3.

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20.8.10 Blank check sector(s) <sector number> <end sector number>

Table 239. ISP Blank check sector command
Command I
Input Start Sector Number:
End Sector Number: Should be greater than or equal to start sector number.
Return Code CMD_SUCCESS |
SECTOR_NOT_BLANK (followed by <Offset of the first non blank word location>
<Contents of non blank word location>) |
INVALID_SECTOR |
PARAM_ERROR |
Description This command is used to blank check one or more sectors of on-chip Flash
memory.
Blank check on sector 0 always fails as first 64 bytes are re-mapped to flash
boot block.
Example "I 2 3<CR><LF>" blank checks the flash sectors 2 and 3.

20.8.11 Read Part Identification number

Table 240. ISP Read Part Identification number command
Command J
Input None.
Return Code CMD_SUCCESS followed by part identification number in ASCII (see Table 241).
Description This command is used to read the part identification number.

Table 241. LPC213x Part Identification numbers

Device ASCII/dec coding Hex coding
LPC2131 and LPC2131/01 196353 0x0002 FF01
LPC2132 and LPC2132/01 196369 0x0002 FF11
LPC2134 and LPC2134/01 196370 0x0002 FF12
LPC2136 and LPC2136/01 196387 0x0002 FF23
LPC2138 and LPC2138/01 196389 0x0002 FF25

20.8.12 Read Boot code version number

Table 242. ISP Read Boot code version number command
Command K
Input None
Return Code CMD_SUCCESS followed by 2 bytes of boot code version number in ASCII format.
It is to be interpreted as <byte1(Major)>.<byte0(Minor)>.
Description This command is used to read the boot code version number.

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20.8.13 Compare <address1> <address2> <no of bytes>

Table 243. ISP Compare command
Command M
Input Address1 (DST): Starting Flash or RAM address of data bytes to be compared.
This address should be a word boundary.
Address2 (SRC): Starting Flash or RAM address of data bytes to be compared.
This address should be a word boundary.
Number of Bytes: Number of bytes to be compared; should be a multiple of 4.
Return Code CMD_SUCCESS | (Source and destination data are equal)
COMPARE_ERROR | (Followed by the offset of first mismatch)
COUNT_ERROR (Byte count is not a multiple of 4) |
ADDR_ERROR |
ADDR_NOT_MAPPED |
PARAM_ERROR |
Description This command is used to compare the memory contents at two locations.
Compare result may not be correct when source or destination address
contains any of the first 64 bytes starting from address zero. First 64 bytes
are re-mapped to flash boot sector
Example "M 8192 1073741824 4<CR><LF>" compares 4 bytes from the RAM address
0x4000 0000 to the 4 bytes from the flash address 0x2000.

20.8.14 ISP Return codes

Table 244. ISP Return codes Summary
Return Mnemonic Description
Code
0 CMD_SUCCESS Command is executed successfully. Sent by ISP
handler only when command given by the host has
been completely and successfully executed.
1 INVALID_COMMAND Invalid command.
2 SRC_ADDR_ERROR Source address is not on word boundary.
3 DST_ADDR_ERROR Destination address is not on a correct boundary.
4 SRC_ADDR_NOT_MAPPED Source address is not mapped in the memory map.
Count value is taken in to consideration where
applicable.
5 DST_ADDR_NOT_MAPPED Destination address is not mapped in the memory
map. Count value is taken in to consideration
where applicable.
6 COUNT_ERROR Byte count is not multiple of 4 or is not a permitted
value.
7 INVALID_SECTOR Sector number is invalid or end sector number is
greater than start sector number.
8 SECTOR_NOT_BLANK Sector is not blank.
9 SECTOR_NOT_PREPARED_FOR_ Command to prepare sector for write operation
WRITE_OPERATION was not executed.
10 COMPARE_ERROR Source and destination data not equal.
11 BUSY Flash programming hardware interface is busy.

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Table 244. ISP Return codes Summary

Return Mnemonic Description
Code
12 PARAM_ERROR Insufficient number of parameters or invalid
parameter.
13 ADDR_ERROR Address is not on word boundary.
14 ADDR_NOT_MAPPED Address is not mapped in the memory map. Count
value is taken in to consideration where applicable.
15 CMD_LOCKED Command is locked.
16 INVALID_CODE Unlock code is invalid.
17 INVALID_BAUD_RATE Invalid baud rate setting.
18 INVALID_STOP_BIT Invalid stop bit setting.
19 CODE_READ_PROTECTION_ Code read protection enabled.
ENABLED

20.9 IAP Commands

For in application programming the IAP routine should be called with a word pointer in
register r0 pointing to memory (RAM) containing command code and parameters. Result
of the IAP command is returned in the result table pointed to by register r1. The user can
reuse the command table for result by passing the same pointer in registers r0 and r1. The
parameter table should be big enough to hold all the results in case if number of results
are more than number of parameters. Parameter passing is illustrated in the Figure 62.
The number of parameters and results vary according to the IAP command. The
maximum number of parameters is 5, passed to the "Copy RAM to FLASH" command.
The maximum number of results is 2, returned by the "Blankcheck sector(s)" command.
The command handler sends the status code INVALID_COMMAND when an undefined
command is received. The IAP routine resides at 0x7FFF FFF0 location and it is thumb
code.

The IAP function could be called in the following way using C.

Define the IAP location entry point. Since the 0th bit of the IAP location is set there will be
a change to Thumb instruction set when the program counter branches to this address.

#define IAP_LOCATION 0x7ffffff1

Define data structure or pointers to pass IAP command table and result table to the IAP
function:

unsigned long command[5];

unsigned long result[3];

unsigned long * command;

unsigned long * result;
command=(unsigned long *) 0x……
result= (unsigned long *) 0x……

Define pointer to function type, which takes two parameters and returns void. Note the IAP
returns the result with the base address of the table residing in R1.
UM10120 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved.

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typedef void (*IAP)(unsigned int [],unsigned int[]);

IAP iap_entry;

Setting function pointer:

iap_entry=(IAP) IAP_LOCATION;

Whenever you wish to call IAP you could use the following statement.

iap_entry (command, result);

The IAP call could be simplified further by using the symbol definition file feature
supported by ARM Linker in ADS (ARM Developer Suite). You could also call the IAP
routine using assembly code.

The following symbol definitions can be used to link IAP routine and user application:

#<SYMDEFS># ARM Linker, ADS1.2 [Build 826]: Last Updated: Wed May 08 16:12:23 2002
0x7fffff90 T rm_init_entry
0x7fffffa0 A rm_undef_handler
0x7fffffb0 A rm_prefetchabort_handler
0x7fffffc0 A rm_dataabort_handler
0x7fffffd0 A rm_irqhandler
0x7fffffe0 A rm_irqhandler2
0x7ffffff0 T iap_entry

As per the ARM specification (The ARM Thumb Procedure Call Standard SWS ESPC
0002 A-05) up to 4 parameters can be passed in the r0, r1, r2 and r3 registers
respectively. Additional parameters are passed on the stack. Up to 4 parameters can be
returned in the r0, r1, r2 and r3 registers respectively. Additional parameters are returned
indirectly via memory. Some of the IAP calls require more than 4 parameters. If the ARM
suggested scheme is used for the parameter passing/returning then it might create
problems due to difference in the C compiler implementation from different vendors. The
suggested parameter passing scheme reduces such risk.

The flash memory is not accessible during a write or erase operation. IAP commands,
which results in a flash write/erase operation, use 32 bytes of space in the top portion of
the on-chip RAM for execution. The user program should not be use this space if IAP flash
programming is permitted in the application.

Table 245. IAP Command Summary

IAP Command Command Code Described in
Prepare sector(s) for write operation 5010 Table 246
Copy RAM to Flash 5110 Table 247
Erase sector(s) 5210 Table 248
Blank check sector(s) 5310 Table 249
Read Part ID 5410 Table 250
Read Boot code version 5510 Table 251
Compare 5610 Table 252
Reinvoke ISP 5710 Table 253

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COMMAND CODE
command
PARAMETER 1 parameter table

PARAMETER 2
ARM REGISTER r0

PARAMETER n
ARM REGISTER r1

STATUS CODE

RESULT 1 command
result table
RESULT 2

RESULT n

Fig 62. IAP Parameter passing

20.9.1 Prepare sector(s) for write operation

This command makes flash write/erase operation a two step process.

Table 246. IAP Prepare sector(s) for write operation command

Command Prepare sector(s) for write operation
Input Command code: 5010
Param0: Start Sector Number
Param1: End Sector Number (should be greater than or equal to start sector
number).
Return Code CMD_SUCCESS |
BUSY |
INVALID_SECTOR
Result None
Description This command must be executed before executing "Copy RAM to Flash" or
"Erase Sector(s)" command. Successful execution of the "Copy RAM to Flash" or
"Erase Sector(s)" command causes relevant sectors to be protected again. The
boot sector can not be prepared by this command. To prepare a single sector use
the same "Start" and "End" sector numbers.

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20.9.2 Copy RAM to Flash

Table 247. IAP Copy RAM to Flash command
Command Copy RAM to Flash
Input Command code: 5110
Param0(DST): Destination Flash address where data bytes are to be written. This
address should be a 256 byte boundary.
Param1(SRC): Source RAM address from which data bytes are to be read. This
address should be a word boundary.
Param2: Number of bytes to be written. Should be 256 | 512 | 1024 | 4096.
Param3: System Clock Frequency (CCLK) in kHz.
Return Code CMD_SUCCESS |
SRC_ADDR_ERROR (Address not a word boundary) |
DST_ADDR_ERROR (Address not on correct boundary) |
SRC_ADDR_NOT_MAPPED |
DST_ADDR_NOT_MAPPED |
COUNT_ERROR (Byte count is not 256 | 512 | 1024 | 4096) |
SECTOR_NOT_PREPARED_FOR_WRITE_OPERATION |
BUSY |
Result None
Description This command is used to program the flash memory. The affected sectors should
be prepared first by calling "Prepare Sector for Write Operation" command. The
affected sectors are automatically protected again once the copy command is
successfully executed. The boot sector can not be written by this command.

20.9.3 Erase sector(s)

Table 248. IAP Erase sector(s) command
Command Erase Sector(s)
Input Command code: 5210
Param0: Start Sector Number
Param1: End Sector Number (should be greater than or equal to start sector
number).
Param2: System Clock Frequency (CCLK) in kHz.
Return Code CMD_SUCCESS |
BUSY |
SECTOR_NOT_PREPARED_FOR_WRITE_OPERATION |
INVALID_SECTOR
Result None
Description This command is used to erase a sector or multiple sectors of on-chip Flash
memory. The boot sector can not be erased by this command. To erase a single
sector use the same "Start" and "End" sector numbers.

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20.9.4 Blank check sector(s)

Table 249. IAP Blank check sector(s) command
Command Blank check sector(s)
Input Command code: 5310
Param0: Start Sector Number
Param1: End Sector Number (should be greater than or equal to start sector
number).
Return Code CMD_SUCCESS |
BUSY |
SECTOR_NOT_BLANK |
INVALID_SECTOR
Result Result0: Offset of the first non blank word location if the Status Code is
SECTOR_NOT_BLANK.
Result1: Contents of non blank word location.
Description This command is used to blank check a sector or multiple sectors of on-chip Flash
memory. To blank check a single sector use the same "Start" and "End" sector
numbers.

20.9.5 Read Part Identification number

Table 250. IAP Read Part Identification command
Command Read part identification number
Input Command code: 5410
Parameters: None
Return Code CMD_SUCCESS |
Result Result0: Part Identification Number (see Table 241 “LPC213x Part Identification
numbers” on page 255 for details)
Description This command is used to read the part identification number.

20.9.6 Read Boot code version number

Table 251. IAP Read Boot code version number command
Command Read boot code version number
Input Command code: 5510
Parameters: None
Return Code CMD_SUCCESS |
Result Result0: 2 bytes of boot code version number in ASCII format. It is to be
interpreted as <byte1(Major)>.<byte0(Minor)>
Description This command is used to read the boot code version number.

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20.9.7 Compare <address1> <address2> <no of bytes>

Table 252. IAP Compare command
Command Compare
Input Command code: 5610
Param0(DST): Starting Flash or RAM address of data bytes to be compared. This
address should be a word boundary.
Param1(SRC): Starting Flash or RAM address of data bytes to be compared. This
address should be a word boundary.
Param2: Number of bytes to be compared; should be a multiple of 4.
Return Code CMD_SUCCESS |
COMPARE_ERROR |
COUNT_ERROR (Byte count is not a multiple of 4) |
ADDR_ERROR |
ADDR_NOT_MAPPED
Result Result0: Offset of the first mismatch if the Status Code is COMPARE_ERROR.
Description This command is used to compare the memory contents at two locations.
The result may not be correct when the source or destination includes any
of the first 64 bytes starting from address zero. The first 64 bytes can be
re-mapped to RAM.

20.9.8 Reinvoke ISP

Table 253. Reinvoke ISP
Command Compare
Input Command code: 5710
Return Code None
Result None.
Description This command is used to invoke the bootloader in ISP mode. This command
maps boot vectors, configures P0.1 as an input and sets the APB divider register
to 0 before entering the ISP mode. This command may be used when a valid user
program is present in the internal flash memory and the P0.14 pin is not
accessible to force the ISP mode. This command does not disable the PLL hence
it is possible to invoke the bootloader when the part is running off the PLL. In such
case the ISP utility should pass the PLL frequency after autobaud handshake.
Another option is to disable the PLL before making this IAP call.

20.9.9 IAP Status codes

Table 254. IAP Status codes Summary
Status Mnemonic Description
Code
0 CMD_SUCCESS Command is executed successfully.
1 INVALID_COMMAND Invalid command.
2 SRC_ADDR_ERROR Source address is not on a word boundary.
3 DST_ADDR_ERROR Destination address is not on a correct boundary.
4 SRC_ADDR_NOT_MAPPED Source address is not mapped in the memory map.
Count value is taken in to consideration where
applicable.

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Table 254. IAP Status codes Summary

Status Mnemonic Description
Code
5 DST_ADDR_NOT_MAPPED Destination address is not mapped in the memory
map. Count value is taken in to consideration where
applicable.
6 COUNT_ERROR Byte count is not multiple of 4 or is not a permitted
value.
7 INVALID_SECTOR Sector number is invalid.
8 SECTOR_NOT_BLANK Sector is not blank.
9 SECTOR_NOT_PREPARED_ Command to prepare sector for write operation was
FOR_WRITE_OPERATION not executed.
10 COMPARE_ERROR Source and destination data is not same.
11 BUSY Flash programming hardware interface is busy.

20.10 JTAG Flash programming interface

Debug tools can write parts of the flash image to the RAM and then execute the IAP call
"Copy RAM to Flash" repeatedly with proper offset.

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Chapter 21: LPC213x EmbeddedTrace
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21.1 Features
• Closely track the instructions that the ARM core is executing.
• One external trigger input
• 10 pin interface
• All registers are programmed through JTAG interface.
• Does not consume power when trace is not being used.
• THUMB instruction set support

21.2 Applications
As the microcontroller has significant amounts of on-chip memories, it is not possible to
determine how the processor core is operating simply by observing the external pins. The
ETM provides real-time trace capability for deeply embedded processor cores. It outputs
information about processor execution to a trace port. A software debugger allows
configuration of the ETM using a JTAG interface and displays the trace information that
has been captured, in a format that a user can easily understand.

21.3 Description
The ETM is connected directly to the ARM core and not to the main AMBA system bus. It
compresses the trace information and exports it through a narrow trace port. An external
Trace Port Analyzer captures the trace information under software debugger control.
Trace port can broadcast the Instruction trace information. Instruction trace (or PC trace)
shows the flow of execution of the processor and provides a list of all the instructions that
were executed. Instruction trace is significantly compressed by only broadcasting branch
addresses as well as a set of status signals that indicate the pipeline status on a cycle by
cycle basis. Trace information generation can be controlled by selecting the trigger
resource. Trigger resources include address comparators, counters and sequencers.
Since trace information is compressed the software debugger requires a static image of
the code being executed. Self-modifying code can not be traced because of this
restriction.

21.3.1 ETM configuration

The following standard configuration is selected for the ETM macrocell.

Table 255. ETM configuration

Resource number/type Small[1]
Pairs of address comparators 1
Data Comparators 0 (Data tracing is not supported)
Memory Map Decoders 4
Counters 1
Sequencer Present No

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Table 255. ETM configuration

Resource number/type Small[1]
External Inputs 2
External Outputs 0
FIFOFULL Present Yes (Not wired)
FIFO depth 10 bytes
Trace Packet Width 4/8

[1] For details refer to ARM documentation "Embedded Trace Macrocell Specification (ARM IHI 0014E)".

21.4 Pin description

Table 256. ETM pin description
Pin Name Type Description
TRACECLK Output Trace Clock. The trace clock signal provides the clock for the trace
port. PIPESTAT[2:0], TRACESYNC, and TRACEPKT[3:0] signals are
referenced to the rising edge of the trace clock. This clock is not
generated by the ETM block. It is to be derived from the system clock.
The clock should be balanced to provide sufficient hold time for the
trace data signals. Half rate clocking mode is supported. Trace data
signals should be shifted by a clock phase from TRACECLK. Refer to
Figure 3.14 page 3.26 and figure 3.15 page 3.27 in "ETM7 Technical
Reference Manual" (ARM DDI 0158B), for example circuits that
implements both half-rate clocking and shifting of the trace data with
respect to the clock. For TRACECLK timings refer to section 5.2 on
page 5-13 in "Embedded Trace Macrocell Specification" (ARM IHI
0014E).
PIPESTAT[2:0] Output Pipe Line status. The pipeline status signals provide a cycle-by-cycle
indication of what is happening in the execution stage of the processor
pipeline.
TRACESYNC Output Trace synchronization. The trace sync signal is used to indicate the
first packet of a group of trace packets and is asserted HIGH only for
the first packet of any branch address.
TRACEPKT[3:0] Output Trace Packet. The trace packet signals are used to output packaged
address and data information related to the pipeline status. All packets
are eight bits in length. A packet is output over two cycles. In the first
cycle, Packet[3:0] is output and in the second cycle, Packet[7:4] is
output.
EXTIN0 Input External Trigger Input

21.5 Reset state of multiplexed pins

On the LPC213x, the ETM pin functions are multiplexed with P1.25-16. To have these
pins come as a Trace port, connect a weak bias resistor (4.7 kΩ) between the
P1.20/TRACESYNC pin and VSS. To have them come up as port pins, do not connect a
bias resistor to P1.20/TRACESYNC, and ensure that any external driver connected to
P1.20/TRACESYNC is either driving high, or is in high-impedance state, during Reset.

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21.6 Register description

The ETM contains 29 registers as shown in Table 257 below. They are described in detail
in the ARM IHI 0014E document published by ARM Limited, which is available via the
Internet.

Table 257. ETM registers

Name Description Access Register
encoding
ETM Control Controls the general operation of the ETM. R/W 000 0000
ETM Configuration Code Allows a debugger to read the number of RO 000 0001
each type of resource.
Trigger Event Holds the controlling event. WO 000 0010
Memory Map Decode Control Eight-bit register, used to statically configure WO 000 0011
the memory map decoder.
ETM Status Holds the pending overflow status bit. RO 000 0100
System Configuration Holds the configuration information using the RO 000 0101
SYSOPT bus.
Trace Enable Control 3 Holds the trace on/off addresses. WO 000 0110
Trace Enable Control 2 Holds the address of the comparison. WO 000 0111
Trace Enable Event Holds the enabling event. WO 000 1000
Trace Enable Control 1 Holds the include and exclude regions. WO 000 1001
FIFOFULL Region Holds the include and exclude regions. WO 000 1010
FIFOFULL Level Holds the level below which the FIFO is WO 000 1011
considered full.
ViewData event Holds the enabling event. WO 000 1100
ViewData Control 1 Holds the include/exclude regions. WO 000 1101
ViewData Control 2 Holds the include/exclude regions. WO 000 1110
ViewData Control 3 Holds the include/exclude regions. WO 000 1111
Address Comparator 1 to 16 Holds the address of the comparison. WO 001 xxxx
Address Access Type 1 to 16 Holds the type of access and the size. WO 010 xxxx
Reserved - - 000 xxxx
Reserved - - 100 xxxx
Initial Counter Value 1 to 4 Holds the initial value of the counter. WO 101 00xx
Counter Enable 1 to 4 Holds the counter clock enable control and WO 101 01xx
event.
Counter reload 1 to 4 Holds the counter reload event. WO 101 10xx
Counter Value 1 to 4 Holds the current counter value. RO 101 11xx
Sequencer State and Control Holds the next state triggering events. - 110 00xx
External Output 1 to 4 Holds the controlling events for each output. WO 110 10xx
Reserved - - 110 11xx
Reserved - - 111 0xxx
Reserved - - 111 1xxx

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21.7 Block diagram

The block diagram of the ETM debug environment is shown below in Figure 63.

APPLICATION PCB

CONNECTOR

TRACE TRACE
10
PORT
ANALYZER ETM
TRIGGER PERIPHERAL

PERIPHERAL

CONNECTOR
Host RAM
running
ARM
debugger JTAG 5
INTERFACE
UNIT
ROM

EMBEDDED ICE

LAN

Fig 63. ETM debug environment block diagram

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Chapter 22: LPC213x EmbeddedICE
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22.1 Features
• No target resources are required by the software debugger in order to start the
debugging session.
• Allows the software debugger to talk via a JTAG (Joint Test Action Group) port directly
to the core.
• Inserts instructions directly in to the ARM7TDMI-S core.
• The ARM7TDMI-S core or the System state can be examined, saved or changed
depending on the type of instruction inserted.
• Allows instructions to execute at a slow debug speed or at a fast system speed.

22.2 Applications
The EmbeddedICE logic provides on-chip debug support. The debugging of the target
system requires a host computer running the debugger software and an EmbeddedICE
protocol convertor. EmbeddedICE protocol convertor converts the Remote Debug
Protocol commands to the JTAG data needed to access the ARM7TDMI-S core present
on the target system.

22.3 Description
The ARM7TDMI-S Debug Architecture uses the existing JTAG1 port as a method of
accessing the core. The scan chains that are around the core for production test are
reused in the debug state to capture information from the databus and to insert new
information into the core or the memory. There are two JTAG-style scan chains within the
ARM7TDMI-S. A JTAG-style Test Access Port Controller controls the scan chains. In
addition to the scan chains, the debug architecture uses EmbeddedICE logic which
resides on chip with the ARM7TDMI-S core. The EmbeddedICE has its own scan chain
that is used to insert watchpoints and breakpoints for the ARM7TDMI-S core. The
EmbeddedICE logic consists of two real time watchpoint registers, together with a control
and status register. One or both of the watchpoint registers can be programmed to halt the
ARM7TDMI-S core. Execution is halted when a match occurs between the values
programmed into the EmbeddedICE logic and the values currently appearing on the
address bus, databus and some control signals. Any bit can be masked so that its value
does not affect the comparison. Either watchpoint register can be configured as a
watchpoint (i.e. on a data access) or a break point (i.e. on an instruction fetch). The
watchpoints and breakpoints can be combined such that:

• The conditions on both watchpoints must be satisfied before the ARM7TDMI core is
stopped. The CHAIN functionality requires two consecutive conditions to be satisfied
before the core is halted. An example of this would be to set the first breakpoint to

1.For more details refer to IEEE Standard 1149.1 - 1990 Standard Test Access Port and Boundary Scan Architecture.

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trigger on an access to a peripheral and the second to trigger on the code segment
that performs the task switching. Therefore when the breakpoints trigger the
information regarding which task has switched out will be ready for examination.
• The watchpoints can be configured such that a range of addresses are enabled for
the watchpoints to be active. The RANGE function allows the breakpoints to be
combined such that a breakpoint is to occur if an access occurs in the bottom 256
bytes of memory but not in the bottom 32 bytes.

The ARM7TDMI-S core has a Debug Communication Channel function in-built. The
debug communication channel allows a program running on the target to communicate
with the host debugger or another separate host without stopping the program flow or
even entering the debug state. The debug communication channel is accessed as a
co-processor 14 by the program running on the ARM7TDMI-S core. The debug
communication channel allows the JTAG port to be used for sending and receiving data
without affecting the normal program flow. The debug communication channel data and
control registers are mapped in to addresses in the EmbeddedICE logic.

22.4 Pin description

Table 258. EmbeddedICE pin description
Pin Name Type Description
TMS Input Test Mode Select. The TMS pin selects the next state in the TAP state
machine.
TCK Input Test Clock. This allows shifting of the data in, on the TMS and TDI pins. It
is a positive edge triggered clock with the TMS and TCK signals that
define the internal state of the device.
TDI Input Test Data In. This is the serial data input for the shift register.
TDO Output Test Data Output. This is the serial data output from the shift register.
Data is shifted out of the device on the negative edge of the TCK signal.
TRST Input Test Reset. The nTRST pin can be used to reset the test logic within the
EmbeddedICE logic.
RTCK Output Returned Test Clock. Extra signal added to the JTAG port. Required for
designs based on ARM7TDMI-S processor core. Multi-ICE (Development
system from ARM) uses this signal to maintain synchronization with
targets having slow or widely varying clock frequency. For details refer to
"Multi-ICE System Design considerations Application Note 72 (ARM DAI
0072A)".

22.5 Reset state of multiplexed pins

On the LPC213x, the pins above are multiplexed with P1.31-26. To have them come up as
a Debug port, connect a weak bias resistor (4.7-10 kΩ depending on the external JTAG
circuitry) between VSS and the P1.26/RTCK pin. To have them come up as GPIO pins, do
not connect a bias resistor, and ensure that any external driver connected to P1.26/RTCK
is either driving high, or is in high-impedance state, during Reset.

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22.6 Register description

The EmbeddedICE logic contains 16 registers as shown in Table 259 below. The
ARM7TDMI-S debug architecture is described in detail in "ARM7TDMI-S (rev 4) Technical
Reference Manual" (ARM DDI 0234A) published by ARM Limited and is available via
Internet.

Table 259. EmbeddedICE logic registers

Name Width Description Address
Debug Control 6 Force debug state, disable interrupts 00000
Debug Status 5 Status of debug 00001
Debug Comms Control Register 32 Debug communication control register 00100
Debug Comms Data Register 32 Debug communication data register 00101
Watchpoint 0 Address Value 32 Holds watchpoint 0 address value 01000
Watchpoint 0 Address Mask 32 Holds watchpoint 0 address mask 01001
Watchpoint 0 Data Value 32 Holds watchpoint 0 data value 01010
Watchpoint 0 Data Mask 32 Holds watchpoint 0 data mask 01011
Watchpoint 0 Control Value 9 Holds watchpoint 0 control value 01100
Watchpoint 0 Control Mask 8 Holds watchpoint 0 control mask 01101
Watchpoint 1 Address Value 32 Holds watchpoint 1 address value 10000
Watchpoint 1 Address Mask 32 Holds watchpoint 1 address mask 10001
Watchpoint 1 Data Value 32 Holds watchpoint 1 data value 10010
Watchpoint 1 Data Mask 32 Holds watchpoint 1 data mask 10011
Watchpoint 1 Control Value 9 Holds watchpoint 1 control value 10100
Watchpoint 1 Control Mask 8 Holds watchpoint 1 control mask 10101

22.7 Block diagram

The block diagram of the debug environment is shown below in Figure 64.

JTAG PORT

serial
parallel
EMBEDDED ICE
interface
INTERFACE 5
EMBEDDED ICE
PROTOCOL
CONVERTER

host running debugger

ARM7TDMI-S

TARGET BOARD

Fig 64. EmbeddedICE debug environment block diagram

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23.1 Features
Remark: RealMonitor is a configurable software module which enables real time debug.
RealMonitor is developed by ARM Inc. Information presented in this chapter is taken from
the ARM document RealMonitor Target Integration Guide (ARM DUI 0142A). It applies to
a specific configuration of RealMonitor software programmed in the on-chip ROM boot
memory of this device. Refer to the white paper "Real Time Debug for System-on-Chip"
available at the ARM webpage.

• Allows user to establish a debug session to a currently running system without halting
or resetting the system.
• Allows user time-critical interrupt code to continue executing while other user
application code is being debugged.

23.2 Applications
Real time debugging.

23.3 Description
RealMonitor is a lightweight debug monitor that allows interrupts to be serviced while user
debug their foreground application. It communicates with the host using the DCC (Debug
Communications Channel), which is present in the EmbeddedICE logic. RealMonitor
provides advantages over the traditional methods for debugging applications in ARM
systems. The traditional methods include:

• Angel (a target-based debug monitor)

• Multi-ICE or other JTAG unit and EmbeddedICE logic (a hardware-based debug
solution).

Although both of these methods provide robust debugging environments, neither is

suitable as a lightweight real-time monitor.

Angel is designed to load and debug independent applications that can run in a variety of
modes, and communicate with the debug host using a variety of connections (such as a
serial port or ethernet). Angel is required to save and restore full processor context, and
the occurrence of interrupts can be delayed as a result. Angel, as a fully functional
target-based debugger, is therefore too heavyweight to perform as a real-time monitor.

Multi-ICE is a hardware debug solution that operates using the EmbeddedICE unit that is
built into most ARM processors. To perform debug tasks such as accessing memory or
the processor registers, Multi-ICE must place the core into a debug state. While the
processor is in this state, which can be millions of cycles, normal program execution is
suspended, and interrupts cannot be serviced.

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RealMonitor combines features and mechanisms from both Angel and Multi-ICE to
provide the services and functions that are required. In particular, it contains both the
Multi-ICE communication mechanisms (the DCC using JTAG), and Angel-like support for
processor context saving and restoring. RealMonitor is pre-programmed in the on-chip
ROM memory (boot sector). When enabled It allows user to observe and debug while
parts of application continue to run. Refer to Section 23.4 “How to enable Realmonitor” on
page 274 for details.

23.3.1 RealMonitor components

As shown in Figure 65, RealMonitor is split in to two functional components:

DEBUGGER

host RDI 1.5.1

REALMONITOR.DLL RMHOST

RDI 1.5.1 RT

RealMonitor
JTAG UNIT
protocol

DCC transmissions
over the JTAG link

RMTARGET
TARGET BOARD AND
target
PROCESSOR
APPLICATION

Fig 65. RealMonitor components

23.3.2 RMHost
This is located between a debugger and a JTAG unit. The RMHost controller,
RealMonitor.dll, converts generic Remote Debug Interface (RDI) requests from the
debugger into DCC-only RDI messages for the JTAG unit. For complete details on
debugging a RealMonitor-integrated application from the host, see the ARM RMHost User
Guide (ARM DUI 0137A).

23.3.3 RMTarget
This is pre-programmed in the on-chip ROM memory (boot sector), and runs on the target
hardware. It uses the EmbeddedICE logic, and communicates with the host using the
DCC. For more details on RMTarget functionality, see the RealMonitor Target Integration
Guide (ARM DUI 0142A).

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23.3.4 How RealMonitor works

In general terms, the RealMonitor operates as a state machine, as shown in Figure 66.
RealMonitor switches between running and stopped states, in response to packets
received by the host, or due to asynchronous events on the target. RMTarget supports the
triggering of only one breakpoint, watchpoint, stop, or semihosting SWI at a time. There is
no provision to allow nested events to be saved and restored. So, for example, if user
application has stopped at one breakpoint, and another breakpoint occurs in an IRQ
handler, RealMonitor enters a panic state. No debugging can be performed after
RealMonitor enters this state.

SWI abort
undef

stop
SWI abort
undef
RUNNING STOPPED PANIC

Fig 66. RealMonitor as a state machine

A debugger such as the ARM eXtended Debugger (AXD) or other RealMonitor aware
debugger, that runs on a host computer, can connect to the target to send commands and
receive data. This communication between host and target is illustrated in Figure 65.

The target component of RealMonitor, RMTarget, communicates with the host component,
RMHost, using the Debug Communications Channel (DCC), which is a reliable link whose
data is carried over the JTAG connection.

While user application is running, RMTarget typically uses IRQs generated by the DCC.
This means that if user application also wants to use IRQs, it must pass any
DCC-generated interrupts to RealMonitor.

To allow nonstop debugging, the EmbeddedICE-RT logic in the processor generates a

Prefetch Abort exception when a breakpoint is reached, or a Data Abort exception when a
watchpoint is hit. These exceptions are handled by the RealMonitor exception handlers
that inform the user, by way of the debugger, of the event. This allows user application to
continue running without stopping the processor. RealMonitor considers user application
to consist of two parts:

• a foreground application running continuously, typically in User, System, or SVC

mode
• a background application containing interrupt and exception handlers that are
triggered by certain events in user system, including:
– IRQs or FIQs
– Data and Prefetch aborts caused by user foreground application. This indicates an
error in the application being debugged. In both cases the host is notified and the
user application is stopped.

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– Undef exception caused by the undefined instructions in user foreground

application. This indicates an error in the application being debugged. RealMonitor
stops the user application until a "Go" packet is received from the host.

When one of these exceptions occur that is not handled by user application, the following
happens:

• RealMonitor enters a loop, polling the DCC. If the DCC read buffer is full, control is
passed to rm_ReceiveData() (RealMonitor internal function). If the DCC write buffer is
free, control is passed to rm_TransmitData() (RealMonitor internal function). If there is
nothing else to do, the function returns to the caller. The ordering of the above
comparisons gives reads from the DCC a higher priority than writes to the
communications link.
• RealMonitor stops the foreground application. Both IRQs and FIQs continue to be
serviced if they were enabled by the application at the time the foreground application
was stopped.

23.4 How to enable Realmonitor

The following steps must be performed to enable RealMonitor. A code example which
implements all the steps can be found at the end of this section.

23.4.1 Adding stacks

User must ensure that stacks are set up within application for each of the processor
modes used by RealMonitor. For each mode, RealMonitor requires a fixed number of
words of stack space. User must therefore allow sufficient stack space for both
RealMonitor and application.

RealMonitor has the following stack requirements:

Table 260. RealMonitor stack requirement

Processor Mode RealMonitor Stack Usage (Bytes)
Undef 48
Prefetch Abort 16
Data Abort 16
IRQ 8

23.4.2 IRQ mode

A stack for this mode is always required. RealMonitor uses two words on entry to its
interrupt handler. These are freed before nested interrupts are enabled.

23.4.3 Undef mode

A stack for this mode is always required. RealMonitor uses 12 words while processing an
undefined instruction exception.

23.4.4 SVC mode

RealMonitor makes no use of this stack.

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23.4.5 Prefetch Abort mode

RealMonitor uses four words on entry to its Prefetch abort interrupt handler.

23.4.6 Data Abort mode

RealMonitor uses four words on entry to its data abort interrupt handler.

23.4.7 User/System mode

RealMonitor makes no use of this stack.

23.4.8 FIQ mode

RealMonitor makes no use of this stack.

23.4.9 Handling exceptions

This section describes the importance of sharing exception handlers between
RealMonitor and user application.

23.4.10 RealMonitor exception handling

To function properly, RealMonitor must be able to intercept certain interrupts and
exceptions. Figure 67 illustrates how exceptions can be claimed by RealMonitor itself, or
shared between RealMonitor and application. If user application requires the exception
sharing, they must provide function (such as app_IRQDispatch ()). Depending on the
nature of the exception, this handler can either:

• Pass control to the RealMonitor processing routine, such as rm_irqhandler2().

• Claim the exception for the application itself, such as app_IRQHandler ().
In a simple case where an application has no exception handlers of its own, the
application can install the RealMonitor low-level exception handlers directly into the vector
table of the processor. Although the irq handler must get the address of the Vectored
Interrupt Controller. The easiest way to do this is to write a branch instruction (<address>)
into the vector table, where the target of the branch is the start address of the relevant
RealMonitor exception handler.

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RealMonitor supplied exception vector handlers

RM_UNDEF_HANDLER()
RESET
RM_PREFETCHABORT_HANDLER()
RM_DATAABORT_HANDLER()
UNDEF RM_IRQHANDLER()

SWI
sharing IRQs between RealMonitor and user IRQ handler
PREFETCH
ABORT RM_IRQHANDLER2()

DATA ABORT
APP_IRQDISPATCH

RESERVED
APP_IRQHANDLER2()
OR
IRQ

FIQ

Fig 67. Exception handlers

23.4.11 RMTarget initialization

While the processor is in a privileged mode, and IRQs are disabled, user must include a
line of code within the start-up sequence of application to call rm_init_entry().

23.4.12 Code example

The following example shows how to setup stack, VIC, initialize RealMonitor and share
non vectored interrupts:

IMPORT rm_init_entry
IMPORT rm_prefetchabort_handler
IMPORT rm_dataabort_handler
IMPORT rm_irqhandler2
IMPORT rm_undef_handler
IMPORT User_Entry ;Entry point of user application.
CODE32
ENTRY
;Define exception table. Instruct linker to place code at address 0x0000 0000

AREA exception_table, CODE

LDR pc, Reset_Address

LDR pc, Undefined_Address
LDR pc, SWI_Address
LDR pc, Prefetch_Address
LDR pc, Abort_Address
NOP ; Insert User code valid signature here.
UM10120 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved.

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LDR pc, [pc, #-0xFF0] ;Load IRQ vector from VIC

LDR PC, FIQ_Address

Reset_Address DCD __init ;Reset Entry point

Undefined_Address DCD rm_undef_handler ;Provided by RealMonitor
SWI_Address DCD 0 ;User can put address of SWI handler here
Prefetch_Address DCD rm_prefetchabort_handler ;Provided by RealMonitor
Abort_Address DCD rm_dataabort_handler ;Provided by RealMonitor
FIQ_Address DCD 0 ;User can put address of FIQ handler here

AREA init_code, CODE

ram_end EQU 0x4000xxxx ; Top of on-chip RAM.

__init
; /*********************************************************************
; * Set up the stack pointers for various processor modes. Stack grows
; * downwards.
; *********************************************************************/
LDR r2, =ram_end ;Get top of RAM
MRS r0, CPSR ;Save current processor mode

; Initialize the Undef mode stack for RealMonitor use

BIC r1, r0, #0x1f
ORR r1, r1, #0x1b
MSR CPSR_c, r1
;Keep top 32 bytes for flash programming routines.
;Refer to Flash Memory System and Programming chapter
SUB sp,r2,#0x1F

; Initialize the Abort mode stack for RealMonitor

BIC r1, r0, #0x1f
ORR r1, r1, #0x17
MSR CPSR_c, r1
;Keep 64 bytes for Undef mode stack
SUB sp,r2,#0x5F

; Initialize the IRQ mode stack for RealMonitor and User

BIC r1, r0, #0x1f
ORR r1, r1, #0x12
MSR CPSR_c, r1
;Keep 32 bytes for Abort mode stack
SUB sp,r2,#0x7F

; Return to the original mode.

MSR CPSR_c, r0

; Initialize the stack for user application

; Keep 256 bytes for IRQ mode stack
SUB sp,r2,#0x17F

; /*********************************************************************

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; * Setup Vectored Interrupt controller. DCC Rx and Tx interrupts

; * generate Non Vectored IRQ request. rm_init_entry is aware
; * of the VIC and it enables the DBGCommRX and DBGCommTx interrupts.
; * Default vector address register is programmed with the address of
; * Non vectored app_irqDispatch mentioned in this example. User can setup
; * Vectored IRQs or FIQs here.
; *********************************************************************/

VICBaseAddr EQU 0xFFFFF000 ; VIC Base address

VICDefVectAddrOffset EQU 0x34

LDR r0, =VICBaseAddr

LDR r1, =app_irqDispatch
STR r1, [r0,#VICDefVectAddrOffset]

BL rm_init_entry ;Initialize RealMonitor

;enable FIQ and IRQ in ARM Processor
MRS r1, CPSR ; get the CPSR
BIC r1, r1, #0xC0 ; enable IRQs and FIQs
MSR CPSR_c, r1 ; update the CPSR
; /*********************************************************************
; * Get the address of the User entry point.
; *********************************************************************/
LDR lr, =User_Entry
MOV pc, lr
; /*********************************************************************
; * Non vectored irq handler (app_irqDispatch)
; *********************************************************************/

AREA app_irqDispatch, CODE

VICVectAddrOffset EQU 0x30
app_irqDispatch

;enable interrupt nesting

STMFD sp!, {r12,r14}
MRS r12, spsr ;Save SPSR in to r12
MSR cpsr_c,0x1F ;Re-enable IRQ, go to system mode

;User should insert code here if non vectored Interrupt sharing is

;required. Each non vectored shared irq handler must return to
;the interrupted instruction by using the following code.
; MSR cpsr_c, #0x52 ;Disable irq, move to IRQ mode
; MSR spsr, r12 ;Restore SPSR from r12
; STMFD sp!, {r0}
; LDR r0, =VICBaseAddr
; STR r1, [r0,#VICVectAddrOffset] ;Acknowledge Non Vectored irq has finished
; LDMFD sp!, {r12,r14,r0} ;Restore registers
; SUBS pc, r14, #4 ;Return to the interrupted instruction

;user interrupt did not happen so call rm_irqhandler2. This handler

;is not aware of the VIC interrupt priority hardware so trick

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;rm_irqhandler2 to return here

STMFD sp!, {ip,pc}

LDR pc, rm_irqhandler2
;rm_irqhandler2 returns here
MSR cpsr_c, #0x52 ;Disable irq, move to IRQ mode
MSR spsr, r12 ;Restore SPSR from r12
STMFD sp!, {r0}
LDR r0, =VICBaseAddr
STR r1, [r0,#VICVectAddrOffset] ;Acknowledge Non Vectored irq has finished
LDMFD sp!, {r12,r14,r0} ;Restore registers
SUBS pc, r14, #4 ;Return to the interrupted instruction

END

23.5 RealMonitor build options

RealMonitor was built with the following options:

RM_OPT_DATALOGGING=FALSE

This option enables or disables support for any target-to-host packets sent on a non
RealMonitor (third-party) channel.

RM_OPT_STOPSTART=TRUE

This option enables or disables support for all stop and start debugging features.

RM_OPT_SOFTBREAKPOINT=TRUE

This option enables or disables support for software breakpoints.

RM_OPT_HARDBREAKPOINT=TRUE

Enabled for cores with EmbeddedICE-RT. This device uses ARM-7TDMI-S Rev 4 with
EmbeddedICE-RT.

RM_OPT_HARDWATCHPOINT=TRUE

Enabled for cores with EmbeddedICE-RT. This device uses ARM-7TDMI-S Rev 4 with
EmbeddedICE-RT.

RM_OPT_SEMIHOSTING=FALSE

This option enables or disables support for SWI semi-hosting. Semi-hosting provides
code running on an ARM target use of facilities on a host computer that is running an
ARM debugger. Examples of such facilities include the keyboard input, screen output,
and disk I/O.

RM_OPT_SAVE_FIQ_REGISTERS=TRUE

This option determines whether the FIQ-mode registers are saved into the registers
block when RealMonitor stops.

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RM_OPT_WRITEBYTES=TRUE

RM_OPT_READHALFWORDS=TRUE

RM_OPT_WRITEHALFWORDS=TRUE

RM_OPT_READWORDS=TRUE

RM_OPT_WRITEWORDS=TRUE

Enables/Disables support for 8/16/32 bit read/write.

RM_OPT_EXECUTECODE=FALSE

Enables/Disables support for executing code from "execute code" buffer. The code
must be downloaded first.

RM_OPT_GETPC=TRUE

This option enables or disables support for the RealMonitor GetPC packet. Useful in
code profiling when real monitor is used in interrupt mode.

RM_EXECUTECODE_SIZE=NA

"execute code" buffer size. Also refer to RM_OPT_EXECUTECODE option.

RM_OPT_GATHER_STATISTICS=FALSE

This option enables or disables the code for gathering statistics about the internal
operation of RealMonitor.

RM_DEBUG=FALSE

This option enables or disables additional debugging and error-checking code in

RealMonitor.

RM_OPT_BUILDIDENTIFIER=FALSE

This option determines whether a build identifier is built into the capabilities table of
RMTarget. Capabilities table is stored in ROM.

RM_OPT_SDM_INFO=FALSE

SDM gives additional information about application board and processor to debug tools.

RM_OPT_MEMORYMAP=FALSE

This option determines whether a memory map of the board is built into the target and
made available through the capabilities table

RM_OPT_USE_INTERRUPTS=TRUE

This option specifies whether RMTarget is built for interrupt-driven mode or polled
mode.

RM_FIFOSIZE=NA

This option specifies the size, in words, of the data logging FIFO buffer.

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CHAIN_VECTORS=FALSE

This option allows RMTarget to support vector chaining through µHAL (ARM HW
abstraction API).

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Chapter 24: Supplementary information
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24.1 Abbreviations
Table 261. Abbreviations
Acronym Description
ADC Analog-to-Digital Converter
BOD Brown-Out Detection
CPU Central Processing Unit
DAC Digital-to-Analog Converter
DCC Debug Communications Channel
FIFO First In, First Out
GPIO General Purpose Input/Output
NA Not Applicable
PLL Phase-Locked Loop
POR Power-On Reset
PWM Pulse Width Modulator
RAM Random Access Memory
SRAM Static Random Access Memory
UART Universal Asynchronous Receiver/Transmitter
VIC Vector Interrupt Controller
APB ARM Peripheral Bus

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24.2 Legal information

24.2.1 Definitions to result in personal injury, death or severe property or environmental

damage. NXP Semiconductors accepts no liability for inclusion and/or use of
NXP Semiconductors products in such equipment or applications and
Draft — The document is a draft version only. The content is still under
therefore such inclusion and/or use is at the customer’s own risk.
internal review and subject to formal approval, which may result in
modifications or additions. NXP Semiconductors does not give any Applications — Applications that are described herein for any of these
representations or warranties as to the accuracy or completeness of products are for illustrative purposes only. NXP Semiconductors makes no
information included herein and shall have no liability for the consequences of representation or warranty that such applications will be suitable for the
use of such information. specified use without further testing or modification.
Customers are responsible for the design and operation of their applications
and products using NXP Semiconductors products, and NXP Semiconductors
24.2.2 Disclaimers accepts no liability for any assistance with applications or customer product
design. It is customer’s sole responsibility to determine whether the NXP
Limited warranty and liability — Information in this document is believed to Semiconductors product is suitable and fit for the customer’s applications and
be accurate and reliable. However, NXP Semiconductors does not give any products planned, as well as for the planned application and use of
representations or warranties, expressed or implied, as to the accuracy or customer’s third party customer(s). Customers should provide appropriate
completeness of such information and shall have no liability for the design and operating safeguards to minimize the risks associated with their
consequences of use of such information. applications and products.
In no event shall NXP Semiconductors be liable for any indirect, incidental, NXP Semiconductors does not accept any liability related to any default,
punitive, special or consequential damages (including - without limitation - lost damage, costs or problem which is based on any weakness or default in the
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changes to information published in this document, including without
limitation specifications and product descriptions, at any time and without
notice. This document supersedes and replaces all information supplied prior
to the publication hereof. 24.2.3 Trademarks
Suitability for use — NXP Semiconductors products are not designed, Notice: All referenced brands, product names, service names and trademarks
authorized or warranted to be suitable for use in life support, life-critical or are the property of their respective owners.
safety-critical systems or equipment, nor in applications where failure or
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24.3 Tables
Table 1. LPC213x and LPC213x/01 device information . .5 Table 37. Pin function Select register 0 (PINSEL0 - address
Table 2. APB peripheries and base addresses . . . . . . .12 0xE002 C000) bit description . . . . . . . . . . . . . 59
Table 3. ARM exception vector locations . . . . . . . . . . . .13 Table 38. Pin function Select register 1 (PINSEL1 - address
Table 4. LPC213x memory mapping modes . . . . . . . . .13 0xE002 C004) bit description . . . . . . . . . . . . . 61
Table 5. MAM responses to program accesses of various Table 39. Pin function Select register 2 (PINSEL2 -
types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19 0xE002 C014) bit description . . . . . . . . . . . . . 63
Table 6. MAM responses to data and DMA accesses of Table 40. Pin function select register bits . . . . . . . . . . . . 63
various types . . . . . . . . . . . . . . . . . . . . . . . . . .20 Table 41. VIC register map . . . . . . . . . . . . . . . . . . . . . . . 65
Table 7. Summary of MAM registers . . . . . . . . . . . . . . .20 Table 42. Software Interrupt register (VICSoftInt - address
Table 8. MAM Control Register (MAMCR - address 0xFFFF F018) bit allocation . . . . . . . . . . . . . . 66
0xE01F C000) bit description . . . . . . . . . . . . . .21 Table 43. Software Interrupt register (VICSoftInt - address
Table 9. MAM Timing register (MAMTIM - address 0xFFFF F018) bit description. . . . . . . . . . . . . . 67
0xE01F C004) bit description . . . . . . . . . . . . . .21 Table 44. Software Interrupt Clear register (VICSoftIntClear
Table 10. Pin summary. . . . . . . . . . . . . . . . . . . . . . . . . . .22 - address 0xFFFF F01C) bit allocation . . . . . . 67
Table 11. Summary of system control registers . . . . . . . .23 Table 45. Software Interrupt Clear register (VICSoftIntClear
Table 12. Recommended values for CX1/X2 in oscillation - address 0xFFFF F01C) bit description . . . . . 67
mode (crystal and external components Table 46. Raw Interrupt status register (VICRawIntr -
parameters) . . . . . . . . . . . . . . . . . . . . . . . . . . .25 address 0xFFFF F008) bit allocation . . . . . . . 68
Table 13. External interrupt registers . . . . . . . . . . . . . . . .26 Table 47. Raw Interrupt status register (VICRawIntr -
Table 14. External Interrupt Flag register (EXTINT - address address 0xFFFF F008) bit description . . . . . . . 68
0xE01F C140) bit description . . . . . . . . . . . . . .27 Table 48. Interrupt Enable register (VICIntEnable - address
Table 15. Interrupt Wakeup register (INTWAKE - address 0xFFFF F010) bit allocation . . . . . . . . . . . . . . 68
0xE01F C144) bit description . . . . . . . . . . . . . .28 Table 49. Interrupt Enable register (VICIntEnable - address
Table 16. External Interrupt Mode register (EXTMODE - 0xFFFF F010) bit description. . . . . . . . . . . . . . 69
address 0xE01F C148) bit description . . . . . . .29 Table 50. Software Interrupt Clear register (VICIntEnClear -
Table 17. External Interrupt Polarity register (EXTPOLAR - address 0xFFFF F014) bit allocation . . . . . . . 69
address 0xE01F C14C) bit description . . . . . . .29 Table 51. Software Interrupt Clear register (VICIntEnClear -
Table 18. System Control and Status flags register (SCS - address 0xFFFF F014) bit description . . . . . . . 69
address 0xE01F C1A0) bit description . . . . . . .31 Table 52. Interrupt Select register (VICIntSelect - address
Table 19. Memory Mapping control register (MEMMAP - 0xFFFF F00C) bit allocation . . . . . . . . . . . . . . 69
address 0xE01F C040) bit description . . . . . . .32 Table 53. Interrupt Select register (VICIntSelect - address
Table 20. PLL registers . . . . . . . . . . . . . . . . . . . . . . . . . .34 0xFFFF F00C) bit description . . . . . . . . . . . . . 70
Table 21. PLL Control register (PLLCON - address Table 54. IRQ Status register (VICIRQStatus - address
0xE01F C080) bit description . . . . . . . . . . . . . .36 0xFFFF F000) bit allocation . . . . . . . . . . . . . . 70
Table 22. PLL Configuration register (PLLCFG - address Table 55. IRQ Status register (VICIRQStatus - address
0xE01F C084) bit description . . . . . . . . . . . . . .36 0xFFFF F000) bit description. . . . . . . . . . . . . . 70
Table 23. PLL Status register (PLLSTAT - address Table 56. FIQ Status register (VICFIQStatus - address
0xE01F C088) bit description . . . . . . . . . . . . . .37 0xFFFF F004) bit allocation . . . . . . . . . . . . . . 71
Table 24. PLL Control bit combinations . . . . . . . . . . . . . .37 Table 57. FIQ Status register (VICFIQStatus - address
Table 25. PLL Feed register (PLLFEED - address 0xFFFF F004) bit description. . . . . . . . . . . . . . 71
0xE01F C08C) bit description. . . . . . . . . . . . . .38 Table 58. Vector Control registers 0-15 (VICvectCntl0-15 -
Table 26. Elements determining PLL’s frequency . . . . . .38 0xFFFF F200-23C) bit description . . . . . . . . . . 71
Table 27. PLL Divider values . . . . . . . . . . . . . . . . . . . . . .39 Table 59. Vector Address registers (VICVectAddr0-15 -
Table 28. PLL Multiplier values . . . . . . . . . . . . . . . . . . . .39 addresses 0xFFFF F100-13C) bit description . 72
Table 29. Power control registers . . . . . . . . . . . . . . . . . . .40 Table 60. Default Vector Address register (VICDefVectAddr
Table 30. Power Control register (PCON - address - address 0xFFFF F034) bit description. . . . . . 72
0xE01F C0C0) bit description. . . . . . . . . . . . . .41 Table 61. Vector Address register (VICVectAddr - address
Table 31. Power Control for Peripherals register (PCONP - 0xFFFF F030) bit description. . . . . . . . . . . . . . 72
address 0xE01F C0C4) bit description . . . . . . .42 Table 62. Protection Enable register (VICProtection -
Table 32. Reset Source Identification Register (RSIR - address 0xFFFF F020) bit description . . . . . . . 73
address 0xE01F C180) bit description . . . . . . .44 Table 63. Connection of interrupt sources to the Vectored
Table 33. APB divider register map . . . . . . . . . . . . . . . . .45 Interrupt Controller (VIC) . . . . . . . . . . . . . . . . . 73
Table 34. APB Divider register (APBDIV - address Table 64. GPIO pin description . . . . . . . . . . . . . . . . . . . . 79
0xE01F C100) bit description . . . . . . . . . . . . . .46 Table 65. GPIO register map (legacy APB accessible
Table 35. Pin description . . . . . . . . . . . . . . . . . . . . . . . . .52 registers) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
Table 36. Pin connect block register map . . . . . . . . . . . .58 Table 66. GPIO register map (local bus accessible registers
UM10120 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved.

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- enhanced GPIO features on LPC213x/01 Table 94. Fast GPIO port 1 output Clear byte and half-word
only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .81 accessible register description. . . . . . . . . . . . . 89
Table 67. GPIO port 0 Direction register (IO0DIR - address Table 95: UART0 pin description . . . . . . . . . . . . . . . . . . . 93
0xE002 8008) bit description . . . . . . . . . . . . . .81 Table 96: UART0 register map . . . . . . . . . . . . . . . . . . . . 94
Table 68. GPIO port 1 Direction register (IO1DIR - address Table 97: UART0 Receiver Buffer Register (U0RBR -
0xE002 8018) bit description . . . . . . . . . . . . . .82 address 0xE000 C000, when DLAB = 0, Read
Table 69. Fast GPIO port 0 Direction register (FIO0DIR - Only) bit description . . . . . . . . . . . . . . . . . . . . 95
address 0x3FFF C000) bit description . . . . . . .82 Table 98: UART0 Transmit Holding Register (U0THR -
Table 70. Fast GPIO port 1 Direction register (FIO1DIR - address 0xE000 C000, when DLAB = 0, Write
address 0x3FFF C020) bit description . . . . . . .82 Only) bit description . . . . . . . . . . . . . . . . . . . . . 95
Table 71. Fast GPIO port 0 Direction control byte and Table 99: UART0 Divisor Latch LSB register (U0DLL -
half-word accessible register description . . . . .82 address 0xE000 C000, when DLAB = 1) bit
Table 72. Fast GPIO port 1 Direction control byte and description . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
half-word accessible register description . . . . .83 Table 100: UART0 Divisor Latch MSB register (U0DLM -
Table 73. Fast GPIO port 0 Mask register (FIO0MASK - address 0xE000 C004, when DLAB = 1) bit
address 0x3FFF C010) bit description . . . . . . .83 description . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
Table 74. Fast GPIO port 1 Mask register (FIO1MASK - Table 101: UART0 Fractional Divider Register (U0FDR -
address 0x3FFF C030) bit description . . . . . . .83 address 0xE000 C028) bit description . . . . . . . 96
Table 75. Fast GPIO port 0 Mask byte and half-word Table 102: Baudrates available when using 20 MHz
accessible register description . . . . . . . . . . . . .84 peripheral clock (PCLK = 20 MHz). . . . . . . . . . 97
Table 76. Fast GPIO port 1 Mask byte and half-word Table 103: UART0 Interrupt Enable Register (U0IER -
accessible register description . . . . . . . . . . . . .84 address 0xE000 C004, when DLAB = 0) bit
Table 77. GPIO port 0 Pin value register (IO0PIN - address description . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
0xE002 8000) bit description . . . . . . . . . . . . . .85 Table 104: UART0 Interrupt Identification Register (UOIIR -
Table 78. GPIO port 1 Pin value register (IO1PIN - address address 0xE000 C008, read only) bit
0xE002 8010) bit description . . . . . . . . . . . . . .85 description . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Table 79. Fast GPIO port 0 Pin value register (FIO0PIN - Table 105: UART0 interrupt handling . . . . . . . . . . . . . . . 100
address 0x3FFF C014) bit description . . . . . . .85 Table 106: UART0 FIFO Control Register (U0FCR - address
Table 80. Fast GPIO port 1 Pin value register (FIO1PIN - 0xE000 C008) bit description. . . . . . . . . . . . . 101
address 0x3FFF C034) bit description . . . . . . .85 Table 107: UART0 Line Control Register (U0LCR - address
Table 81. Fast GPIO port 0 Pin value byte and half-word 0xE000 C00C) bit description . . . . . . . . . . . . 102
accessible register description . . . . . . . . . . . . .86 Table 108: UART0 Line Status Register (U0LSR - address
Table 82. Fast GPIO port 1 Pin value byte and half-word 0xE000 C014, read only) bit description . . . . 102
accessible register description . . . . . . . . . . . . .86 Table 109: UART0 Scratch pad register (U0SCR - address
Table 83. GPIO port 0 output Set register (IO0SET - address 0xE000 C01C) bit description . . . . . . . . . . . . 103
0xE002 8004 bit description . . . . . . . . . . . . . . .87 Table 110: Auto-baud Control Register (U0ACR -
Table 84. GPIO port 1 output Set register (IO1SET - address 0xE000 C020) bit description. . . . . . . . . . . . . 104
0xE002 8014) bit description . . . . . . . . . . . . . .87 Table 111: UART0 Transmit Enable Register (U0TER -
Table 85. Fast GPIO port 0 output Set register (FIO0SET - address 0xE000 C030) bit description . . . . . . 107
address 0x3FFF C018) bit description . . . . . . .87 Table 112: UART1 pin description. . . . . . . . . . . . . . . . . . 109
Table 86. Fast GPIO port 1 output Set register (FIO1SET - Table 113: UART1 register map . . . . . . . . . . . . . . . . . . . 110
address 0x3FFF C038) bit description . . . . . . .87 Table 114: UART1 Receiver Buffer Register (U1RBR -
Table 87. Fast GPIO port 0 output Set byte and half-word address 0xE001 0000, when DLAB = 0 Read
accessible register description . . . . . . . . . . . . .87 Only) bit description . . . . . . . . . . . . . . . . . . . 111
Table 88. Fast GPIO port 1 output Set byte and half-word Table 115: UART1 Transmitter Holding Register (U1THR -
accessible register description . . . . . . . . . . . . .88 address 0xE001 0000, when DLAB = 0 Write
Table 89. GPIO port 0 output Clear register 0 (IO0CLR - Only) bit description . . . . . . . . . . . . . . . . . . . . 111
address 0xE002 800C) bit description . . . . . . .88 Table 116: UART1 Divisor Latch LSB register (U1DLL -
Table 90. GPIO port 1 output Clear register 1 (IO1CLR - address 0xE001 0000, when DLAB = 1) bit
address 0xE002 801C) bit description . . . . . . .88 description . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
Table 91. Fast GPIO port 0 output Clear register 0 Table 117: UART1 Divisor Latch MSB register (U1DLM -
(FIO0CLR - address 0x3FFF C01C) bit address 0xE001 0004, when DLAB = 1) bit
description . . . . . . . . . . . . . . . . . . . . . . . . . . . .88 description . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
Table 92. Fast GPIO port 1 output Clear register 1 Table 118: UART1 Fractional Divider Register (U1FDR -
(FIO1CLR - address 0x3FFF C03C) bit address 0xE001 0028) bit description . . . . . . 112
description . . . . . . . . . . . . . . . . . . . . . . . . . . . .89 Table 119: Baudrates available when using 20 MHz
Table 93. Fast GPIO port 0 output Clear byte and half-word peripheral clock (PCLK = 20 MHz). . . . . . . . . 113
accessible register description . . . . . . . . . . . . .89 Table 120: UART1 Interrupt Enable Register (U1IER -

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address 0xE001 0004, when DLAB = 0) bit mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154

description . . . . . . . . . . . . . . . . . . . . . . . . . . . 114 Table 153. I2CnCONSET used to configure Slave mode 155
Table 121: UART1 Interrupt Identification Register (U1IIR - Table 154. Summary of I2C registers . . . . . . . . . . . . . . . 161
address 0xE001 0008, read only) bit Table 155. I2C Control Set Register (I2C[0/1]CONSET -
description . . . . . . . . . . . . . . . . . . . . . . . . . . . 116 addresses: 0xE001 C000, 0xE005 C000) bit
Table 122: UART1 interrupt handling . . . . . . . . . . . . . . . 117 description . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
Table 123: UART1 FIFO Control Register (U1FCR - address Table 156. I2C Control Set Register (I2C[0/1]CONCLR -
0xE001 0008) bit description . . . . . . . . . . . . . 118 addresses 0xE001 C018, 0xE005 C018) bit
Table 124: UART1 Line Control Register (U1LCR - address description . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
0xE001 000C) bit description . . . . . . . . . . . . . 118 Table 157. I2C Status Register (I2C[0/1]STAT - addresses
Table 125: UART1 Modem Control Register (U1MCR - 0xE001 C004, 0xE005 C004) bit description . 164
address 0xE001 0010) bit description . . . . . . 119 Table 158. I2C Data Register (I2C[0/1]DAT - addresses
Table 126. Modem status interrupt generation . . . . . . . .121 0xE001 C008, 0xE005 C008) bit description . 165
Table 127: UART1 Line Status Register (U1LSR - address Table 159. I2C Slave Address register (I2C[0/1]ADR -
0xE001 0014, read only) bit description . . . . .122 addresses 0xE001 C00C, 0xE005 C00C) bit
Table 128: UART1 Modem Status Register (U1MSR - description . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
address 0xE001 0018) bit description . . . . . .123 Table 160. I2C SCL High Duty Cycle register (I2C[0/1]SCLH
Table 129: UART1 Scratch pad register (U1SCR - address - addresses 0xE001 C010, 0xE005 C010) bit
0xE001 0014) bit description . . . . . . . . . . . . .124 description . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
Table 130: Auto-baud Control Register (U1ACR - Table 161. I2C SCL Low Duty Cycle register (I2C[0/1]SCLL -
0xE001 0020) bit description . . . . . . . . . . . . .124 addresses 0xE001 C014, 0xE005 C014) bit
Table 131: UART1 Transmit Enable Register (U1TER - description . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
address 0xE001 0030) bit description . . . . . .127 Table 162. Example I2C clock rates . . . . . . . . . . . . . . . . 166
Table 132. SPI data to clock phase relationship . . . . . . .130 Table 163. Abbreviations used to describe an I2C
Table 133. SPI pin description . . . . . . . . . . . . . . . . . . . . .133 operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
Table 134. SPI register map . . . . . . . . . . . . . . . . . . . . . .133 Table 164. I2CONSET used to initialize Master Transmitter
Table 135: SPI Control Register (S0SPCR - address mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
0xE002 0000) bit description . . . . . . . . . . . . .134 Table 165. I2C0ADR and I2C1ADR usage in Slave Receiver
Table 136: SPI Status Register (S0SPSR - address mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
0xE002 0004) bit description . . . . . . . . . . . . .135 Table 166. I2C0CONSET and I2C1CONSET used to
Table 137: SPI Data Register (S0SPDR - address initialize Slave Receiver mode . . . . . . . . . . . . 168
0xE002 0008) bit description . . . . . . . . . . . . .136 Table 167. Master Transmitter mode . . . . . . . . . . . . . . . 174
Table 138: SPI Clock Counter Register (S0SPCCR - address Table 168. Master Receiver mode . . . . . . . . . . . . . . . . . 175
0xE002 000C) bit description . . . . . . . . . . . . .136 Table 169. Slave Receiver Mode . . . . . . . . . . . . . . . . . . 176
Table 139: SPI Interrupt register (S0SPINT - address Table 170. Tad_105: Slave Transmitter mode . . . . . . . . 178
0xE002 001C) bit description . . . . . . . . . . . . .136 Table 171. Miscellaneous states . . . . . . . . . . . . . . . . . . . 180
Table 140. SSP pin descriptions . . . . . . . . . . . . . . . . . . .139 Table 172. Timer/Counter pin description . . . . . . . . . . . . 192
Table 141. SSP register map. . . . . . . . . . . . . . . . . . . . . .147 Table 173. TIMER/COUNTER0 and TIMER/COUNTER1
Table 142: SSP Control Register 0 (SSPCR0 - address register map . . . . . . . . . . . . . . . . . . . . . . . . . . 193
0xE006 8000) bit description . . . . . . . . . . . . .147 Table 174: Interrupt Register (IR, TIMER0: T0IR - address
Table 143: SSP Control Register 1 (SSPCR1 - address 0xE000 4000 and TIMER1: T1IR - address
0xE006 8004) bit description . . . . . . . . . . . . .148 0xE000 8000) bit description . . . . . . . . . . . . . 194
Table 144: SSP Data Register (SSPDR - address Table 175: Timer Control Register (TCR, TIMER0: T0TCR -
0xE006 8008) bit description . . . . . . . . . . . . .149 address 0xE000 4004 and TIMER1: T1TCR -
Table 145: SSP Status Register (SSPSR - address address 0xE000 8004) bit description . . . . . . 195
0xE006 800C) bit description . . . . . . . . . . . . .149 Table 176: Count Control Register (CTCR, TIMER0:
Table 146: SSP Clock Prescale Register (SSPCPSR - T0CTCR - address 0xE000 4070 and TIMER1:
address 0xE006 8010) bit description . . . . . .149 T1CTCR - address 0xE000 8070) bit
Table 147: SSP Interrupt Mask Set/Clear register (SSPIMSC description . . . . . . . . . . . . . . . . . . . . . . . . . . . 195
- address 0xE006 8014) bit description . . . . .150 Table 177: Match Control Register (MCR, TIMER0: T0MCR -
Table 148: SSP Raw Interrupt Status register (SSPRIS - address 0xE000 4014 and TIMER1: T1MCR -
address 0xE006 8018) bit description . . . . . .150 address 0xE000 8014) bit description . . . . . . 197
Table 149: SSP Masked Interrupt Status register (SSPMIS Table 178: Capture Control Register (CCR, TIMER0: T0CCR
-address 0xE006 801C) bit description. . . . . .151 - address 0xE000 4028 and TIMER1: T1CCR -
Table 150: SSP interrupt Clear Register (SSPICR - address address 0xE000 8028) bit description . . . . . . 198
0xE006 8020) bit description . . . . . . . . . . . . .151 Table 179: External Match Register (EMR, TIMER0: T0EMR
Table 151. I2C Pin Description. . . . . . . . . . . . . . . . . . . . .153 - address 0xE000 403C and TIMER1: T1EMR -
Table 152. I2CnCONSET used to configure Master address0xE000 803C) bit description . . . . . . 199

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Table 180. External match control . . . . . . . . . . . . . . . . . .199 0xE006 0000) bit description . . . . . . . . . . . . . 233
Table 181. Set and reset inputs for PWM Flip-Flops . . . .205 Table 216: A/D Global Data Register (AD0GDR - address
Table 182. Pin summary . . . . . . . . . . . . . . . . . . . . . . . . .206 0xE003 4004 and AD1GDR - address
Table 183. Pulse Width Modulator (PWM) register map .207 0xE006 0004) bit description . . . . . . . . . . . . . 234
Table 184: PWM Interrupt Register (PWMIR - address Table 217: A/D Global Start Register (ADGSR - address
0xE001 4000) bit description . . . . . . . . . . . . .208 0xE003 4008) bit description . . . . . . . . . . . . . 235
Table 185: PWM Timer Control Register (PWMTCR - Table 218: A/D Status Register (ADSTAT, ADC0: AD0STAT -
address 0xE001 4004) bit description . . . . . .209 address 0xE003 4030 and ADC1: AD1STAT -
Table 186: PWM Match Control Register (PWMMCR - address 0xE006 0030) bit description . . . . . . 236
address 0xE001 4014) bit description . . . . . .210 Table 219: A/D Status Register (ADSTAT, ADC0: AD0STAT -
Table 187: PWM Control Register (PWMPCR - address address 0xE003 4004 and ADC1: AD1STAT -
0xE001 404C) bit description . . . . . . . . . . . . . 211 address 0xE006 0004) bit description . . . . . . 236
Table 188: PWM Latch Enable Register (PWMLER - address Table 220: A/D Data Registers (ADDR0 to ADDR7, ADC0:
0xE001 4050) bit description . . . . . . . . . . . . .213 AD0DR0 to AD0DR7 - 0xE003 4010 to 0xE003
Table 189. Watchdog register map . . . . . . . . . . . . . . . . .215 402C and ADC1: AD1DR0 to AD1DR7- 0xE006
Table 190. Watchdog operating modes selection . . . . . .215 0010 to 0xE006 402C) bit description . . . . . . 237
Table 191: Watchdog Mode register (WDMOD - address Table 221. DAC pin description . . . . . . . . . . . . . . . . . . . 239
0xE000 0000) bit description . . . . . . . . . . . . .216 Table 222: DAC Register (DACR - address 0xE006 C000) bit
Table 192: Watchdog Timer Constant register (WDTC - description . . . . . . . . . . . . . . . . . . . . . . . . . . . 239
address 0xE000 0004) bit description . . . . . .216 Table 223. Flash sectors in LPC2131, LPC2132, LPC2134,
Table 193: Watchdog Feed register (WDFEED - address LPC2136 and LPC2138 . . . . . . . . . . . . . . . . . 246
0xE000 0008) bit description . . . . . . . . . . . . .216 Table 224. Code Read Protection levels. . . . . . . . . . . . . 248
Table 194: Watchdog Timer Value register (WDTV - address Table 225. Code Read Protection hardware/software
0xE000 000C) bit description . . . . . . . . . . . . .216 interaction . . . . . . . . . . . . . . . . . . . . . . . . . . . 248
Table 195. Real Time Clock (RTC) register map . . . . . . .219 Table 226. Code read protection options for different
Table 196. Miscellaneous registers . . . . . . . . . . . . . . . . .220 bootloader revisions. . . . . . . . . . . . . . . . . . . . 249
Table 197: Interrupt Location Register (ILR - address Table 227. Bootloader revisions . . . . . . . . . . . . . . . . . . . 250
0xE002 4000) bit description . . . . . . . . . . . . .221 Table 228. ISP command summary . . . . . . . . . . . . . . . . 250
Table 198: Clock Tick Counter Register (CTCR - address Table 229. ISP Unlock command . . . . . . . . . . . . . . . . . . 250
0xE002 4004) bit description . . . . . . . . . . . . .221 Table 230. ISP Set Baud Rate command . . . . . . . . . . . . 251
Table 199: Clock Control Register (CCR - address Table 231. Correlation between possible ISP baudrates and
0xE002 4008) bit description . . . . . . . . . . . . .221 external crystal frequency (in MHz) . . . . . . . . 251
Table 200: Counter Increment Interrupt Register (CIIR - Table 232. ISP Echo command . . . . . . . . . . . . . . . . . . . 251
address 0xE002 400C) bit description . . . . . .222 Table 233. ISP Write to RAM command . . . . . . . . . . . . . 252
Table 201: Alarm Mask Register (AMR - address Table 234. ISP Read memory command . . . . . . . . . . . . 253
0xE002 4010) bit description . . . . . . . . . . . . .222 Table 235. ISP Prepare sector(s) for write operation
Table 202: Consolidated Time register 0 (CTIME0 - address command . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253
0xE002 4014) bit description . . . . . . . . . . . . .223 Table 236. ISP Copy command . . . . . . . . . . . . . . . . . . . 254
Table 203: Consolidated Time register 1 (CTIME1 - address Table 237. ISP Go command . . . . . . . . . . . . . . . . . . . . . 254
0xE002 4018) bit description . . . . . . . . . . . . .223 Table 238. ISP Erase sector command . . . . . . . . . . . . . 255
Table 204: Consolidated Time register 2 (CTIME2 - address Table 239. ISP Blank check sector command . . . . . . . . 255
0xE002 401C) bit description . . . . . . . . . . . . .224 Table 240. ISP Read Part Identification number
Table 205. Time counter relationships and values . . . . .224 command . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255
Table 206. Time counter registers . . . . . . . . . . . . . . . . . .224 Table 241. LPC213x Part Identification numbers . . . . . . 256
Table 207. Alarm registers. . . . . . . . . . . . . . . . . . . . . . . .225 Table 242. ISP Read Boot code version number
Table 208. Reference clock divider registers. . . . . . . . . .226 command . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256
Table 209: Prescaler Integer register (PREINT - address Table 243. ISP Compare command . . . . . . . . . . . . . . . . 256
0xE002 4080) bit description . . . . . . . . . . . . .227 Table 244. ISP Return codes Summary . . . . . . . . . . . . . 257
Table 210: Prescaler Integer register (PREFRAC - address Table 245. IAP Command Summary . . . . . . . . . . . . . . . 259
0xE002 4084) bit description . . . . . . . . . . . . .227 Table 246. IAP Prepare sector(s) for write operation
Table 211. Prescaler cases where the Integer Counter reload command . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260
value is incremented. . . . . . . . . . . . . . . . . . . .229 Table 247. IAP Copy RAM to Flash command . . . . . . . . 260
Table 212. Recommended values for the RTC external Table 248. IAP Erase sector(s) command . . . . . . . . . . . 261
32 kHz oscillator CX1/X2 components . . . . . . .230 Table 249. IAP Blank check sector(s) command . . . . . . 261
Table 213. ADC pin description . . . . . . . . . . . . . . . . . . . .231 Table 250. IAP Read Part Identification command . . . . . 261
Table 214. ADC registers. . . . . . . . . . . . . . . . . . . . . . . . .232 Table 251. IAP Read Boot code version number
Table 215: A/D Control Register (AD0CR - address command . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262
0xE003 4000 and AD1CR - address Table 252. IAP Compare command . . . . . . . . . . . . . . . . 262

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Table 253. Reinvoke ISP . . . . . . . . . . . . . . . . . . . . . . . . .262

Table 254. IAP Status codes Summary . . . . . . . . . . . . . .263
Table 255. ETM configuration . . . . . . . . . . . . . . . . . . . . .264
Table 256. ETM pin description . . . . . . . . . . . . . . . . . . . .265
Table 257. ETM registers. . . . . . . . . . . . . . . . . . . . . . . . .266
Table 258. EmbeddedICE pin description . . . . . . . . . . . .269
Table 259. EmbeddedICE logic registers . . . . . . . . . . . .270
Table 260. RealMonitor stack requirement . . . . . . . . . . .274
Table 261. Abbreviations . . . . . . . . . . . . . . . . . . . . . . . .282

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24.4 Figures
Fig 1. LPC213x block diagram. . . . . . . . . . . . . . . . . . . . .8 Fig 40. I2C Bus serial interface block diagram . . . . . . . 158
Fig 2. System memory map . . . . . . . . . . . . . . . . . . . . . . .9 Fig 41. Arbitration procedure. . . . . . . . . . . . . . . . . . . . . 159
Fig 3. Peripheral memory map. . . . . . . . . . . . . . . . . . . .10 Fig 42. Serial clock synchronization . . . . . . . . . . . . . . . 160
Fig 4. AHB peripheral map . . . . . . . . . . . . . . . . . . . . . . 11 Fig 43. Format and States in the Master Transmitter
Fig 5. Map of lower memory is showing re-mapped and mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
re-mappable areas (LPC2138 and LPC2138/01 with Fig 44. Format and States in the Master Receiver
512 kB Flash). . . . . . . . . . . . . . . . . . . . . . . . . . . .15 mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
Fig 6. Simplified block diagram of the Memory Accelerator Fig 45. Format and States in the Slave Receiver mode 172
Module (MAM) . . . . . . . . . . . . . . . . . . . . . . . . . . .18 Fig 46. Format and States in the Slave Transmitter
Fig 7. Oscillator modes and models: a) slave mode of mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
operation, b) oscillation mode of operation, c) Fig 47. Simultaneous repeated START conditions from 2
external crystal model used for CX1/X2 evaluation24 masters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
Fig 8. FOSC selection algorithm . . . . . . . . . . . . . . . . . . .25 Fig 48. Forced access to a busy I2C bus . . . . . . . . . . . 182
Fig 9. External interrupt logic . . . . . . . . . . . . . . . . . . . . .31 Fig 49. Recovering from a bus obstruction caused by a low
Fig 10. PLL block diagram . . . . . . . . . . . . . . . . . . . . . . . .35 level on SDA . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
Fig 11. Reset block diagram including the wakeup timer.44 Fig 50. A timer cycle in which PR=2, MRx=6, and both
Fig 12. APB divider connections . . . . . . . . . . . . . . . . . . .46 interrupt and reset on match are enabled . . . . . 200
Fig 13. LPC2131 and LPC2131/01 64-pin package . . . .49 Fig 51. A timer cycle in which PR=2, MRx=6, and both
Fig 14. LPC2132 and LPC2132/01 64-pin package . . . .50 interrupt and stop on match are enabled . . . . . 200
Fig 15. LPC2134, LPC2136, LPC2138, LPC2134/01, Fig 52. Timer block diagram . . . . . . . . . . . . . . . . . . . . . 201
LPC2136/01 and LPC2138/01 64-pin package . .51 Fig 53. PWM block diagram . . . . . . . . . . . . . . . . . . . . . 204
Fig 16. Block diagram of the Vectored Interrupt Controller Fig 54. Sample PWM waveforms . . . . . . . . . . . . . . . . . 205
(VIC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .74 Fig 55. Watchdog block diagram. . . . . . . . . . . . . . . . . . 217
Fig 17. Illustration of the fast and slow GPIO access and Fig 56. RTC block diagram . . . . . . . . . . . . . . . . . . . . . . 218
output showing 3.5 x increase of the pin output Fig 57. RTC prescaler block diagram . . . . . . . . . . . . . . 228
frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .92 Fig 58. RTC 32kHz crystal oscillator circuit. . . . . . . . . . 229
Fig 18. Autobaud a) mode 0 and b) mode 1 waveform..106 Fig 59. Suggested ADC interface . . . . . . . . . . . . . . . . . 238
Fig 19. UART0 block diagram . . . . . . . . . . . . . . . . . . . .108 Fig 60. Map of lower memory after reset . . . . . . . . . . . 242
Fig 20. Auto-RTS functional timing . . . . . . . . . . . . . . . .120 Fig 61. Boot process flowchart . . . . . . . . . . . . . . . . . . . 245
Fig 21. Auto-CTS functional timing . . . . . . . . . . . . . . . .121 Fig 62. IAP Parameter passing . . . . . . . . . . . . . . . . . . . 259
Fig 22. Autobaud a) mode 0 and b) mode 1 waveform..126 Fig 63. ETM debug environment block diagram . . . . . . 267
Fig 23. UART1 block diagram . . . . . . . . . . . . . . . . . . . .128 Fig 64. EmbeddedICE debug environment block
Fig 24. SPI data transfer format (CPHA = 0 and diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 270
CPHA = 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .130 Fig 65. RealMonitor components . . . . . . . . . . . . . . . . . 272
Fig 25. SPI block diagram . . . . . . . . . . . . . . . . . . . . . . .137 Fig 66. RealMonitor as a state machine . . . . . . . . . . . . 273
Fig 26. Texas Instruments synchronous serial frame format: Fig 67. Exception handlers . . . . . . . . . . . . . . . . . . . . . . 276
a) single frame transfer and b)
continuous/back-to-back two frames. . . . . . . . .140
Fig 27. Motorola SPI frame format with CPOL=0 and
CPHA=0 ( a) single transfer and b) continuous
transfer) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .141
Fig 28. SPI frame format with CPOL=0 and CPHA=1 . .142
Fig 29. SPI frame format with CPOL = 1 and CPHA = 0 ( a)
single and b) continuous transfer) . . . . . . . . . . .143
Fig 30. SPI frame format with CPOL = 1 and CPHA = 1144
Fig 31. Microwire frame format (single transfer) . . . . . .145
Fig 32. Microwire frame format (continuos transfers) . .146
Fig 33. Microwire frame format (continuos transfers,
details) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .146
Fig 34. I2C bus configuration . . . . . . . . . . . . . . . . . . . . .153
Fig 35. Format in the Master Transmitter mode. . . . . . .154
Fig 36. Format of Master Receive mode . . . . . . . . . . . .155
Fig 37. A master receiver switch to master Transmitter after
sending repeated START. . . . . . . . . . . . . . . . . .155
Fig 38. Format of Slave Receiver mode . . . . . . . . . . . .156
Fig 39. Format of Slave Transmitter mode . . . . . . . . . .156
UM10120 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved.

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24.5 Contents
Chapter 1: Introductory information
1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.6 Architectural overview . . . . . . . . . . . . . . . . . . . 5
1.2 Enhancements introduced with LPC213x/01 1.7 ARM7TDMI-S processor . . . . . . . . . . . . . . . . . . 5
devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.8 On-chip Flash memory system . . . . . . . . . . . . 6
1.3 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.9 On-chip Static RAM (SRAM). . . . . . . . . . . . . . . 6
1.4 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.10 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.5 Device information . . . . . . . . . . . . . . . . . . . . . . 5

Chapter 2: LPC213x Memory map

2.1 Memory maps. . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.2.1 Memory map concepts and operating modes 12
2.2 LPC213x memory re-mapping and boot block . . 2.2.2 Memory re-mapping. . . . . . . . . . . . . . . . . . . . 13
12 2.3 Prefetch abort and data abort exceptions . . 16

Chapter 3: LPC213x Memory accelerator module

3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 3.5 MAM configuration . . . . . . . . . . . . . . . . . . . . . 20
3.2 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 3.6 Register description . . . . . . . . . . . . . . . . . . . . 20
3.3 MAM blocks . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 3.7 MAM Control Register (MAMCR -
3.3.1 Flash memory bank . . . . . . . . . . . . . . . . . . . . 18 0xE01F C000). . . . . . . . . . . . . . . . . . . . . . . . . . 20
3.3.2 Instruction latches and data latches . . . . . . . . 18 3.8 MAM Timing register (MAMTIM -
3.3.3 Flash programming issues . . . . . . . . . . . . . . . 19 0xE01F C004). . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.4 MAM operating modes . . . . . . . . . . . . . . . . . . 19 3.9 MAM usage notes . . . . . . . . . . . . . . . . . . . . . . 21

Chapter 4: LPC213x System control

4.1 Summary of system control block functions 22 4.8.3 PLL Configuration register (PLLCFG -
4.2 Pin description . . . . . . . . . . . . . . . . . . . . . . . . . 22 0xE01F C084) . . . . . . . . . . . . . . . . . . . . . . . . 36
4.3 Register description . . . . . . . . . . . . . . . . . . . . 23 4.8.4 PLL Status register (PLLSTAT -
0xE01F C088) . . . . . . . . . . . . . . . . . . . . . . . . 36
4.4 Crystal oscillator . . . . . . . . . . . . . . . . . . . . . . . 24
4.8.5 PLL Interrupt . . . . . . . . . . . . . . . . . . . . . . . . . 37
4.5 External interrupt inputs . . . . . . . . . . . . . . . . . 26 4.8.6 PLL Modes. . . . . . . . . . . . . . . . . . . . . . . . . . . 37
4.5.1 Register description . . . . . . . . . . . . . . . . . . . . 26 4.8.7 PLL Feed register (PLLFEED - 0xE01F C08C) 37
4.5.2 External Interrupt Flag register (EXTINT - 4.8.8 PLL and Power-down mode. . . . . . . . . . . . . . 38
0xE01F C140) . . . . . . . . . . . . . . . . . . . . . . . . 26 4.8.9 PLL frequency calculation . . . . . . . . . . . . . . . 38
4.5.3 Interrupt Wake-up register (INTWAKE - 4.8.10 Procedure for determining PLL settings. . . . . 39
0xE01F C144) . . . . . . . . . . . . . . . . . . . . . . . . 28 4.8.11 PLL example . . . . . . . . . . . . . . . . . . . . . . . . . 39
4.5.4 External Interrupt Mode register (EXTMODE - 4.9 Power control . . . . . . . . . . . . . . . . . . . . . . . . . 40
0xE01F C148) . . . . . . . . . . . . . . . . . . . . . . . . 28
4.9.1 Register description . . . . . . . . . . . . . . . . . . . . 40
4.5.5 External Interrupt Polarity register (EXTPOLAR -
4.9.2 Power Control register (PCON -
0xE01F C14C) . . . . . . . . . . . . . . . . . . . . . . . . 29
0xE01F C0C0) . . . . . . . . . . . . . . . . . . . . . . . . 40
4.5.6 Multiple external interrupt pins . . . . . . . . . . . . 30
4.9.3 Power Control for Peripherals register (PCONP -
4.6 Other system controls. . . . . . . . . . . . . . . . . . . 31 0xE01F C0C4) . . . . . . . . . . . . . . . . . . . . . . . . 41
4.6.1 System Control and Status flags register (SCS - 4.9.4 Power control usage notes . . . . . . . . . . . . . . 42
0xE01F C1A0) . . . . . . . . . . . . . . . . . . . . . . . . 31 4.10 Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
4.7 Memory mapping control . . . . . . . . . . . . . . . . 32 4.10.1 Reset Source Identification Register (RSIR -
4.7.1 Memory Mapping control register (MEMMAP - 0xE01F C180) . . . . . . . . . . . . . . . . . . . . . . . . 44
0xE01F C040) . . . . . . . . . . . . . . . . . . . . . . . . 32 4.11 APB divider . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
4.7.2 Memory mapping control usage notes . . . . . . 32
4.11.1 Register description . . . . . . . . . . . . . . . . . . . . 45
4.8 Phase Locked Loop (PLL). . . . . . . . . . . . . . . . 33 4.11.2 APBDIV register (APBDIV - 0xE01F C100) . . 45
4.8.1 Register description . . . . . . . . . . . . . . . . . . . . 33 4.12 Wake-up timer . . . . . . . . . . . . . . . . . . . . . . . . . 46
4.8.2 PLL Control register (PLLCON -
4.13 Brown-out detection . . . . . . . . . . . . . . . . . . . . 47
0xE01F C080) . . . . . . . . . . . . . . . . . . . . . . . . 35
4.14 Code security vs debugging . . . . . . . . . . . . . 48
UM10120 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved.

User manual Rev. 3 — 4 October 2010 290 of 297

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Chapter 5: LPC213x Pin configuration

5.1 LPC213x pinout . . . . . . . . . . . . . . . . . . . . . . . . 49 5.2 Pin description for LPC213x . . . . . . . . . . . . . 51

Chapter 6: LPC213x Pin connect block

6.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 6.4.2 Pin function Select register 1 (PINSEL1 -
6.2 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 0xE002 C004) . . . . . . . . . . . . . . . . . . . . . . . . 60
6.3 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 6.4.3 Pin function Select register 2 (PINSEL2 -
0xE002 C014) . . . . . . . . . . . . . . . . . . . . . . . . 62
6.4 Register description . . . . . . . . . . . . . . . . . . . . 58
6.4.4 Pin function select register values . . . . . . . . . 63
6.4.1 Pin Function Select Register 0 (PINSEL0 -
0xE002 C000). . . . . . . . . . . . . . . . . . . . . . . . . 59

Chapter 7: LPC213x VIC

7.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 7.4.10 Vector Address registers 0-15 (VICVectAddr0-15 -
7.2 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 0xFFFF F100-13C) . . . . . . . . . . . . . . . . . . . . 72
7.3 Register description . . . . . . . . . . . . . . . . . . . . 64 7.4.11 Default Vector Address register (VICDefVectAddr
- 0xFFFF F034) . . . . . . . . . . . . . . . . . . . . . . . 72
7.4 VIC registers. . . . . . . . . . . . . . . . . . . . . . . . . . . 66
7.4.12 Vector Address register (VICVectAddr -
7.4.1 Software Interrupt register (VICSoftInt - 0xFFFF F030) . . . . . . . . . . . . . . . . . . . . . . . . 72
0xFFFF F018). . . . . . . . . . . . . . . . . . . . . . . . . 66 7.4.13 Protection Enable register (VICProtection -
7.4.2 Software Interrupt Clear register (VICSoftIntClear 0xFFFF F020) . . . . . . . . . . . . . . . . . . . . . . . . 72
- 0xFFFF F01C) . . . . . . . . . . . . . . . . . . . . . . . 67
7.5 Interrupt sources. . . . . . . . . . . . . . . . . . . . . . . 73
7.4.3 Raw Interrupt status register (VICRawIntr -
0xFFFF F008). . . . . . . . . . . . . . . . . . . . . . . . . 68 7.6 Spurious interrupts . . . . . . . . . . . . . . . . . . . . . 75
7.4.4 Interrupt Enable register (VICIntEnable - 7.6.1 Details and case studies on spurious
0xFFFF F010). . . . . . . . . . . . . . . . . . . . . . . . . 68 interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
7.4.5 Interrupt Enable Clear register (VICIntEnClear - 7.6.2 Workaround . . . . . . . . . . . . . . . . . . . . . . . . . . 76
0xFFFF F014). . . . . . . . . . . . . . . . . . . . . . . . . 69 7.6.3 Solution 1: test for an IRQ received during a write
7.4.6 Interrupt Select register (VICIntSelect - to disable IRQs . . . . . . . . . . . . . . . . . . . . . . . 76
0xFFFF F00C) . . . . . . . . . . . . . . . . . . . . . . . . 69 7.6.4 Solution 2: disable IRQs and FIQs using separate
7.4.7 IRQ Status register (VICIRQStatus - writes to the CPSR. . . . . . . . . . . . . . . . . . . . . 77
0xFFFF F000). . . . . . . . . . . . . . . . . . . . . . . . . 70 7.6.5 Solution 3: re-enable FIQs at the beginning of the
7.4.8 FIQ Status register (VICFIQStatus - IRQ handler . . . . . . . . . . . . . . . . . . . . . . . . . . 77
0xFFFF F004). . . . . . . . . . . . . . . . . . . . . . . . . 71 7.7 VIC usage notes . . . . . . . . . . . . . . . . . . . . . . . 77
7.4.9 Vector Control registers 0-15 (VICvectCntl0-15 -
0xFFFF F200-23C) . . . . . . . . . . . . . . . . . . . . . 71

Chapter 8: LPC213x GPIO

8.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 8.4.4 GPIO port output Set register (IOSET, Port 0:
8.2 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 IO0SET - 0xE002 8004 and Port 1: IO1SET -
8.3 Pin description . . . . . . . . . . . . . . . . . . . . . . . . . 79 0xE002 8014; FIOSET, Port 0: FIO0SET -
0x3FFF C018 and Port 1: FIO1SET -
8.4 Register description . . . . . . . . . . . . . . . . . . . . 79
0x3FFF C038) . . . . . . . . . . . . . . . . . . . . . . . . 86
8.4.1 GPIO port Direction register (IODIR, Port 0: 8.4.5 GPIO port output Clear register (IOCLR, Port 0:
IO0DIR - 0xE002 8008 and Port 1: IO1DIR - IO0CLR - 0xE002 800C and Port 1: IO1CLR -
0xE002 8018; FIODIR, Port 0: FIO0DIR - 0xE002 801C; FIOCLR, Port 0: FIO0CLR -
0x3FFF C000 and Port 1:FIO1DIR - 0x3FFF C01C and Port 1: FIO1CLR -
0x3FFF C020) . . . . . . . . . . . . . . . . . . . . . . . . 81 0x3FFF C03C) . . . . . . . . . . . . . . . . . . . . . . . . 88
8.4.2 Fast GPIO port Mask register (FIOMASK, Port 0:
8.5 GPIO usage notes . . . . . . . . . . . . . . . . . . . . . . 90
FIO0MASK - 0x3FFF C010 and Port
1:FIO1MASK - 0x3FFF C030) . . . . . . . . . . . . 83 8.5.1 Example 1: sequential accesses to IOSET and
8.4.3 GPIO port Pin value register (IOPIN, Port 0: IOCLR affecting the same GPIO pin/bit . . . . . 90
IO0PIN - 0xE002 8000 and Port 1: IO1PIN - 8.5.2 Example 2: an immediate output of 0s and 1s on
0xE002 8010; FIOPIN, Port 0: FIO0PIN - a GPIO port . . . . . . . . . . . . . . . . . . . . . . . . . . 90
0x3FFF C014 and Port 1: FIO1PIN - 8.5.3 Writing to IOSET/IOCLR vs IOPIN. . . . . . . . . 91
0x3FFF C034) . . . . . . . . . . . . . . . . . . . . . . . . 84

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8.5.4 Output signal frequency considerations when

using the legacy and enhanced GPIO registers . .
91

Chapter 9: LPC213x UART0

9.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 9.3.7 UART0 Interrupt Identification Register (U0IIR -
9.1.1 Enhancements introduced with LPC213x/01 0xE000 C008, Read Only) . . . . . . . . . . . . . . . 99
devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 9.3.8 UART0 FIFO Control Register (U0FCR -
9.2 Pin description . . . . . . . . . . . . . . . . . . . . . . . . . 93 0xE000 C008) . . . . . . . . . . . . . . . . . . . . . . . 101
9.3.9 UART0 Line Control Register (U0LCR -
9.3 Register description . . . . . . . . . . . . . . . . . . . . 93
0xE000 C00C) . . . . . . . . . . . . . . . . . . . . . . . 101
9.3.1 UART0 Receiver Buffer Register (U0RBR -
9.3.10 UART0 Line Status Register (U0LSR -
0xE000 C000, when DLAB = 0, Read Only). . 95
0xE000 C014, Read Only) . . . . . . . . . . . . . . 102
9.3.2 UART0 Transmit Holding Register (U0THR -
9.3.11 UART0 Scratch pad register (U0SCR -
0xE000 C000, when DLAB = 0, Write Only) . . 95
0xE000 C01C) . . . . . . . . . . . . . . . . . . . . . . . 103
9.3.3 UART0 Divisor Latch Registers (U0DLL -
9.3.12 UART0 Auto-baud Control Register (U0ACR -
0xE000 C000 and U0DLM - 0xE000 C004, when
0xE000 C020) . . . . . . . . . . . . . . . . . . . . . . . 103
DLAB = 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
9.3.13 Auto-baud . . . . . . . . . . . . . . . . . . . . . . . . . . 104
9.3.4 UART0 Fractional Divider Register (U0FDR -
9.3.13.1 Auto-baud Modes. . . . . . . . . . . . . . . . . . . . . 105
0xE000 C028). . . . . . . . . . . . . . . . . . . . . . . . . 96
9.3.14 UART0 Transmit Enable Register (U0TER -
9.3.5 UART0 baudrate calculation. . . . . . . . . . . . . . 97
0xE000 C030) . . . . . . . . . . . . . . . . . . . . . . . 106
9.3.6 UART0 Interrupt Enable Register (U0IER -
0xE000 C004, when DLAB = 0) . . . . . . . . . . . 98 9.4 Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . 107

Chapter 10: LPC213x UART1

10.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 10.3.8 UART1 FIFO Control Register (U1FCR -
10.1.1 Enhancements introduced with LPC213x/01 0xE001 0008). . . . . . . . . . . . . . . . . . . . . . . . . 118
devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 10.3.9 UART1 Line Control Register (U1LCR -
10.2 Pin description . . . . . . . . . . . . . . . . . . . . . . . . 109 0xE001 000C) . . . . . . . . . . . . . . . . . . . . . . . . 118
10.3.10 UART1 Modem Control Register (U1MCR -
10.3 Register description . . . . . . . . . . . . . . . . . . . 109
0xE001 0010). . . . . . . . . . . . . . . . . . . . . . . . . 119
10.3.1 UART1 Receiver Buffer Register (U1RBR -
10.3.10.1 Auto-flow control . . . . . . . . . . . . . . . . . . . . . 120
0xE001 0000, when DLAB = 0 Read Only) . 111
10.3.11 UART1 Line Status Register (U1LSR -
10.3.2 UART1 Transmitter Holding Register (U1THR -
0xE001 0014, Read Only) . . . . . . . . . . . . . . 121
0xE001 0000, when DLAB = 0 Write Only) . 111
10.3.12 UART1 Modem Status Register (U1MSR -
10.3.3 UART1 Divisor Latch Registers 0 and 1 (U1DLL -
0xE001 0018). . . . . . . . . . . . . . . . . . . . . . . . 123
0xE001 0000 and U1DLM - 0xE001 0004, when
10.3.13 UART1 Scratch pad register (U1SCR -
DLAB = 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
0xE001 001C) . . . . . . . . . . . . . . . . . . . . . . . 123
10.3.4 UART1 Fractional Divider Register (U1FDR -
10.3.14 UART1 Auto-baud Control Register (U1ACR -
0xE001 0028) . . . . . . . . . . . . . . . . . . . . . . . . 112
0xE001 0020). . . . . . . . . . . . . . . . . . . . . . . . 124
10.3.5 UART1 baudrate calculation. . . . . . . . . . . . . 113
10.3.15 Auto-baud . . . . . . . . . . . . . . . . . . . . . . . . . . 124
10.3.6 UART1 Interrupt Enable Register (U1IER -
10.3.16 Auto-baud Modes. . . . . . . . . . . . . . . . . . . . . 125
0xE001 0004, when DLAB = 0) . . . . . . . . . . 114
10.3.17 UART1 Transmit Enable Register (U1TER -
10.3.7 UART1 Interrupt Identification Register (U1IIR -
0xE001 0030). . . . . . . . . . . . . . . . . . . . . . . . 126
0xE001 0008, Read Only) . . . . . . . . . . . . . . 115
10.4 Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . 127

Chapter 11: LPC213x SPI

11.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129 11.4 Register description . . . . . . . . . . . . . . . . . . . 133
11.2 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . 129 11.4.1 SPI Control Register (S0SPCR -
11.2.1 SPI overview. . . . . . . . . . . . . . . . . . . . . . . . . 129 0xE002 0000). . . . . . . . . . . . . . . . . . . . . . . . 134
11.2.2 SPI data transfers . . . . . . . . . . . . . . . . . . . . . 129 11.4.2 SPI Status Register (S0SPSR -
11.2.3 General information . . . . . . . . . . . . . . . . . . . 131 0xE002 0004). . . . . . . . . . . . . . . . . . . . . . . . 135
11.2.4 Master operation. . . . . . . . . . . . . . . . . . . . . . 131 11.4.3 SPI Data Register (S0SPDR - 0xE002 0008) 136
11.2.5 Slave operation. . . . . . . . . . . . . . . . . . . . . . . 132 11.4.4 SPI Clock Counter Register (S0SPCCR -
11.2.6 Exception conditions. . . . . . . . . . . . . . . . . . . 132 0xE002 000C) . . . . . . . . . . . . . . . . . . . . . . . 136
11.3 Pin description . . . . . . . . . . . . . . . . . . . . . . . . 133 11.4.5 SPI Interrupt register (S0SPINT -
0xE002 001C) . . . . . . . . . . . . . . . . . . . . . . . 136
UM10120 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved.

User manual Rev. 3 — 4 October 2010 292 of 297

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11.5 Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . 136

Chapter 12: LPC213x SPI1/SSP

12.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138 12.4.1 SSP Control Register 0 (SSPCR0 -
12.2 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . 138 0xE006 8000). . . . . . . . . . . . . . . . . . . . . . . . 147
12.3 Bus description . . . . . . . . . . . . . . . . . . . . . . . 139 12.4.2 SSP Control Register 1 (SSPCR1 -
0xE006 8004). . . . . . . . . . . . . . . . . . . . . . . . 148
12.3.1 Texas Instruments Synchronous Serial (SSI)
12.4.3 SSP Data Register (SSPDR - 0xE006 8008) 149
frame format . . . . . . . . . . . . . . . . . . . . . . . . . 139
12.4.4 SSP Status Register (SSPSR -
12.3.2 SPI frame format . . . . . . . . . . . . . . . . . . . . . 140
0xE006 800C) . . . . . . . . . . . . . . . . . . . . . . . 149
12.3.3 Clock Polarity (CPOL) and Clock Phase (CPHA)
12.4.5 SSP Clock Prescale Register (SSPCPSR -
control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
0xE006 8010). . . . . . . . . . . . . . . . . . . . . . . . 149
12.3.4 SPI format with CPOL=0,CPHA=0 . . . . . . . . 141
12.4.6 SSP Interrupt Mask Set/Clear register (SSPIMSC
12.3.5 SPI format with CPOL=0,CPHA=1 . . . . . . . . 142
- 0xE006 8014) . . . . . . . . . . . . . . . . . . . . . . 150
12.3.6 SPI format with CPOL = 1,CPHA = 0 . . . . . . 143
12.4.7 SSP Raw Interrupt Status register (SSPRIS -
12.3.7 SPI format with CPOL = 1,CPHA = 1 . . . . . . 144
0xE006 8018). . . . . . . . . . . . . . . . . . . . . . . . 150
12.3.8 Semiconductor Microwire frame format . . . . 144
12.4.8 SSP Masked Interrupt register (SSPMIS -
12.3.9 Setup and hold time requirements on CS with
0xE006 801C) . . . . . . . . . . . . . . . . . . . . . . . 151
respect to SK in Microwire mode . . . . . . . . . 146
12.4.9 SSP Interrupt Clear Register (SSPICR -
12.4 Register description . . . . . . . . . . . . . . . . . . . 146 0xE006 8020). . . . . . . . . . . . . . . . . . . . . . . . 151

Chapter 13: LPC213x I2C-bus interfaces I2C0/1

13.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152 13.7.8 Selecting the appropriate I2C data rate and duty
13.2 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . 152 cycle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
13.3 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . 152 13.8 Details of I2C operating modes . . . . . . . . . . 166
13.4 Pin description . . . . . . . . . . . . . . . . . . . . . . . . 153 13.8.1 Master Transmitter mode . . . . . . . . . . . . . . . 167
13.8.2 Master Receiver mode. . . . . . . . . . . . . . . . . 168
13.5 I2C operating modes . . . . . . . . . . . . . . . . . . . 153
13.8.3 Slave Receiver mode. . . . . . . . . . . . . . . . . . 168
13.5.1 Master Transmitter mode . . . . . . . . . . . . . . . 153
13.8.4 Slave Transmitter mode . . . . . . . . . . . . . . . . 173
13.5.2 Master Receiver mode . . . . . . . . . . . . . . . . . 154
13.8.5 Miscellaneous states . . . . . . . . . . . . . . . . . . 179
13.5.3 Slave Receiver mode . . . . . . . . . . . . . . . . . . 155
13.8.5.1 I2STAT = 0xF8 . . . . . . . . . . . . . . . . . . . . . . . 179
13.5.4 Slave Transmitter mode . . . . . . . . . . . . . . . . 156
13.8.5.2 I2STAT = 0x00 . . . . . . . . . . . . . . . . . . . . . . . 179
13.6 I2C implementation and operation . . . . . . . . 157 13.8.6 Some special cases . . . . . . . . . . . . . . . . . . . 180
13.6.1 Input filters and output stages. . . . . . . . . . . . 157 13.8.7 Simultaneous repeated START conditions from
13.6.2 Address Register I2ADDR . . . . . . . . . . . . . . 159 two masters . . . . . . . . . . . . . . . . . . . . . . . . . 180
13.6.3 Comparator. . . . . . . . . . . . . . . . . . . . . . . . . . 159 13.8.8 Data transfer after loss of arbitration . . . . . . 180
13.6.4 Shift register I2DAT. . . . . . . . . . . . . . . . . . . . 159 13.8.9 Forced access to the I2C bus. . . . . . . . . . . . 180
13.6.5 Arbitration and synchronization logic . . . . . . 159 13.8.10 I2C Bus obstructed by a Low level on SCL or
13.6.6 Serial clock generator . . . . . . . . . . . . . . . . . . 160 SDA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
13.6.7 Timing and control . . . . . . . . . . . . . . . . . . . . 160 13.8.11 Bus error . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
13.6.8 Control register I2CONSET and I2CONCLR 160 13.8.12 I2C State service routines. . . . . . . . . . . . . . . 182
13.6.9 Status decoder and status register . . . . . . . . 161 13.8.12.1 Initialization . . . . . . . . . . . . . . . . . . . . . . . . . 182
13.7 Register description . . . . . . . . . . . . . . . . . . . 161 13.8.12.2 I2C interrupt service . . . . . . . . . . . . . . . . . . . 183
13.7.1 I2C Control Set Register (I2C[0/1]CONSET: 13.8.12.3 The state service routines . . . . . . . . . . . . . . 183
0xE001 C000, 0xE005 C000) . . . . . . . . . . . . 162 13.8.12.4 Adapting state services to an application. . . 183
13.7.2 I2C Control Clear Register (I2C[0/1]CONCLR: 13.9 Software example . . . . . . . . . . . . . . . . . . . . . 183
0xE001 C018, 0xE005 C018) . . . . . . . . . . . . 164 13.9.1 Initialization routine . . . . . . . . . . . . . . . . . . . 183
13.7.3 I2C Status Register (I2C[0/1]STAT - 13.9.2 Start master transmit function . . . . . . . . . . . 183
0xE001 C004, 0xE005 C004) . . . . . . . . . . . . 164 13.9.3 Start master receive function . . . . . . . . . . . . 183
13.7.4 I2C Data Register (I2C[0/1]DAT - 0xE001 C008, 13.9.4 I2C interrupt routine . . . . . . . . . . . . . . . . . . . 184
0xE005 C008). . . . . . . . . . . . . . . . . . . . . . . . 165 13.9.5 Non mode specific states . . . . . . . . . . . . . . . 184
13.7.5 I2C Slave Address Register (I2C[0/1]ADR - 13.9.5.1 State: 0x00 . . . . . . . . . . . . . . . . . . . . . . . . . . 184
0xE001 C00C, 0xE005 C00C) . . . . . . . . . . . 165 13.9.6 Master states . . . . . . . . . . . . . . . . . . . . . . . . 184
13.7.6 I2C SCL High Duty Cycle Register (I2C[0/1]SCLH 13.9.6.1 State: 0x08 . . . . . . . . . . . . . . . . . . . . . . . . . . 184
- 0xE001 C010, 0xE005 C010). . . . . . . . . . . 165 13.9.6.2 State: 0x10 . . . . . . . . . . . . . . . . . . . . . . . . . . 184
13.7.7 I2C SCL Low Duty Cycle Register (I2C[0/1]SCLL - 13.9.7 Master Transmitter states . . . . . . . . . . . . . . 185
0xE001 C014, 0xE005 C014) . . . . . . . . . . . . 165 13.9.7.1 State: 0x18 . . . . . . . . . . . . . . . . . . . . . . . . . . 185
UM10120 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved.

User manual Rev. 3 — 4 October 2010 293 of 297

NXP Semiconductors UM10120
Chapter 24: Supplementary information

13.9.7.2 State: 0x20 . . . . . . . . . . . . . . . . . . . . . . . . . . 185 13.9.9.4 State: 0x78 . . . . . . . . . . . . . . . . . . . . . . . . . . 187

13.9.7.3 State: 0x28 . . . . . . . . . . . . . . . . . . . . . . . . . . 185 13.9.9.5 State: 0x80 . . . . . . . . . . . . . . . . . . . . . . . . . . 188
13.9.7.4 State: 0x30 . . . . . . . . . . . . . . . . . . . . . . . . . . 185 13.9.9.6 State: 0x88 . . . . . . . . . . . . . . . . . . . . . . . . . . 188
13.9.7.5 State: 0x38 . . . . . . . . . . . . . . . . . . . . . . . . . . 186 13.9.9.7 State: 0x90 . . . . . . . . . . . . . . . . . . . . . . . . . . 188
13.9.8 Master Receive states . . . . . . . . . . . . . . . . . 186 13.9.9.8 State: 0x98 . . . . . . . . . . . . . . . . . . . . . . . . . . 188
13.9.8.1 State: 0x40 . . . . . . . . . . . . . . . . . . . . . . . . . . 186 13.9.9.9 State: 0xA0. . . . . . . . . . . . . . . . . . . . . . . . . . 188
13.9.8.2 State: 0x48 . . . . . . . . . . . . . . . . . . . . . . . . . . 186 13.9.10 Slave Transmitter States . . . . . . . . . . . . . . . 189
13.9.8.3 State: 0x50 . . . . . . . . . . . . . . . . . . . . . . . . . . 186 13.9.10.1 State: 0xA8. . . . . . . . . . . . . . . . . . . . . . . . . . 189
13.9.8.4 State: 0x58 . . . . . . . . . . . . . . . . . . . . . . . . . . 186 13.9.10.2 State: 0xB0. . . . . . . . . . . . . . . . . . . . . . . . . . 189
13.9.9 Slave Receiver states . . . . . . . . . . . . . . . . . . 187 13.9.10.3 State: 0xB8. . . . . . . . . . . . . . . . . . . . . . . . . . 189
13.9.9.1 State: 0x60 . . . . . . . . . . . . . . . . . . . . . . . . . . 187 13.9.10.4 State: 0xC0 . . . . . . . . . . . . . . . . . . . . . . . . . 189
13.9.9.2 State: 0x68 . . . . . . . . . . . . . . . . . . . . . . . . . . 187 13.9.10.5 State: 0xC8 . . . . . . . . . . . . . . . . . . . . . . . . . 190
13.9.9.3 State: 0x70 . . . . . . . . . . . . . . . . . . . . . . . . . . 187

Chapter 14: LPC213x Timer

14.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191 14.5.5 Prescale Register (PR, TIMER0: T0PR -
14.2 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . 191 0xE000 400C and TIMER1:
14.3 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . 191 T1PR - 0xE000 800C) . . . . . . . . . . . . . . . . . 196
14.5.6 Prescale Counter Register (PC, TIMER0: T0PC -
14.4 Pin description . . . . . . . . . . . . . . . . . . . . . . . . 191
0xE000 4010 and TIMER1: T1PC -
14.5 Register description . . . . . . . . . . . . . . . . . . . 192 0xE000 8010). . . . . . . . . . . . . . . . . . . . . . . . 196
14.5.1 Interrupt Register (IR, TIMER0: T0IR - 14.5.7 Match Registers (MR0 - MR3) . . . . . . . . . . . 196
0xE000 4000 and TIMER1: T1IR - 14.5.8 Match Control Register (MCR, TIMER0: T0MCR -
0xE000 8000) . . . . . . . . . . . . . . . . . . . . . . . . 194 0xE000 4014 and TIMER1: T1MCR -
14.5.2 Timer Control Register (TCR, TIMER0: T0TCR - 0xE000 8014). . . . . . . . . . . . . . . . . . . . . . . . 197
0xE000 4004 and TIMER1: T1TCR - 14.5.9 Capture Registers (CR0 - CR3) . . . . . . . . . . 197
0xE000 8004) . . . . . . . . . . . . . . . . . . . . . . . . 194 14.5.10 Capture Control Register (CCR, TIMER0: T0CCR
14.5.3 Count Control Register (CTCR, TIMER0: - 0xE000 4028 and TIMER1: T1CCR -
T0CTCR - 0xE000 4070 and TIMER1: T1CTCR - 0xE000 8028). . . . . . . . . . . . . . . . . . . . . . . . 198
0xE000 8070) . . . . . . . . . . . . . . . . . . . . . . . . 195 14.5.11 External Match Register (EMR, TIMER0: T0EMR
14.5.4 Timer Counter (TC, TIMER0: T0TC - - 0xE000 403C; and TIMER1: T1EMR -
0xE000 4008 and TIMER1: T1TC - 0xE000 803C) . . . . . . . . . . . . . . . . . . . . . . . 199
0xE000 8008) . . . . . . . . . . . . . . . . . . . . . . . . 196 14.6 Example timer operation . . . . . . . . . . . . . . . 200
14.7 Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . 200

Chapter 15: LPC213x PWM

15.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202 15.4.3 PWM Timer Counter (PWMTC -
15.2 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . 202 0xE001 4008). . . . . . . . . . . . . . . . . . . . . . . . 209
15.2.1 Rules for single edge controlled 15.4.4 PWM Prescale Register (PWMPR -
PWM outputs . . . . . . . . . . . . . . . . . . . . . . . . 206 0xE001 400C) . . . . . . . . . . . . . . . . . . . . . . . 209
15.2.2 Rules for double edge controlled PWM 15.4.5 PWM Prescale Counter register (PWMPC -
outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206 0xE001 4010). . . . . . . . . . . . . . . . . . . . . . . . 209
15.4.6 PWM Match Registers (PWMMR0 -
15.3 Pin description . . . . . . . . . . . . . . . . . . . . . . . . 206
PWMMR6) . . . . . . . . . . . . . . . . . . . . . . . . . . 210
15.4 Register description . . . . . . . . . . . . . . . . . . . 206 15.4.7 PWM Match Control Register (PWMMCR -
15.4.1 PWM Interrupt Register (PWMIR - 0xE001 4014). . . . . . . . . . . . . . . . . . . . . . . . 210
0xE001 4000) . . . . . . . . . . . . . . . . . . . . . . . . 208 15.4.8 PWM Control Register (PWMPCR -
15.4.2 PWM Timer Control Register (PWMTCR - 0xE001 404C) . . . . . . . . . . . . . . . . . . . . . . . . 211
0xE001 4004) . . . . . . . . . . . . . . . . . . . . . . . . 208 15.4.9 PWM Latch Enable Register (PWMLER -
0xE001 4050). . . . . . . . . . . . . . . . . . . . . . . . 212

Chapter 16: LPC213x WDT

16.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214 16.4.1 Watchdog Mode register (WDMOD -
16.2 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . 214 0xE000 0000). . . . . . . . . . . . . . . . . . . . . . . . 215
16.3 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . 214 16.4.2 Watchdog Timer Constant register (WDTC -
0xE000 0004). . . . . . . . . . . . . . . . . . . . . . . . 216
16.4 Register description . . . . . . . . . . . . . . . . . . . 215
UM10120 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved.

User manual Rev. 3 — 4 October 2010 294 of 297

NXP Semiconductors UM10120
Chapter 24: Supplementary information

16.4.3 Watchdog Feed register (WDFEED - 16.4.4 Watchdog Timer Value register (WDTV -
0xE000 0008) . . . . . . . . . . . . . . . . . . . . . . . . 216 0xE000 000C) . . . . . . . . . . . . . . . . . . . . . . . 216
16.5 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . 217

Chapter 17: LPC213x RTC

17.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218 17.4.10 Consolidated Time register 1 (CTIME1 -
17.2 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . 218 0xE002 4018). . . . . . . . . . . . . . . . . . . . . . . . 223
17.3 Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . 218 17.4.11 Consolidated Time register 2 (CTIME2 -
0xE002 401C) . . . . . . . . . . . . . . . . . . . . . . . 224
17.4 Register description . . . . . . . . . . . . . . . . . . . 219
17.4.12 Time counter group . . . . . . . . . . . . . . . . . . . 224
17.4.1 RTC interrupts . . . . . . . . . . . . . . . . . . . . . . . 220 17.4.13 Leap year calculation . . . . . . . . . . . . . . . . . . 225
17.4.2 Miscellaneous register group . . . . . . . . . . . . 220 17.4.14 Alarm register group . . . . . . . . . . . . . . . . . . 225
17.4.3 Interrupt Location Register (ILR -
17.5 RTC usage notes. . . . . . . . . . . . . . . . . . . . . . 225
0xE002 4000) . . . . . . . . . . . . . . . . . . . . . . . . 220
17.4.4 Clock Tick Counter Register (CTCR - 17.6 Reference clock divider (prescaler) . . . . . . 226
0xE002 4004) . . . . . . . . . . . . . . . . . . . . . . . . 221 17.6.1 Prescaler Integer register (PREINT -
17.4.5 Clock Control Register (CCR - 0xE002 4008) 221 0xE002 4080). . . . . . . . . . . . . . . . . . . . . . . . 227
17.4.6 Counter Increment Interrupt Register (CIIR - 17.6.2 Prescaler Fraction register (PREFRAC -
0xE002 400C). . . . . . . . . . . . . . . . . . . . . . . . 222 0xE002 4084). . . . . . . . . . . . . . . . . . . . . . . . 227
17.4.7 Alarm Mask Register (AMR - 0xE002 4010). 222 17.6.3 Example of prescaler usage . . . . . . . . . . . . 227
17.4.8 Consolidated time registers . . . . . . . . . . . . . 223 17.6.4 Prescaler operation . . . . . . . . . . . . . . . . . . . 228
17.4.9 Consolidated Time register 0 (CTIME0 - 17.7 RTC external 32 kHz oscillator component
0xE002 4014) . . . . . . . . . . . . . . . . . . . . . . . . 223 selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229

Chapter 18: LPC213x ADC

18.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231 18.4.4 A/D Status Register (ADSTAT, ADC0: AD0STAT -
18.1.1 Enhancements introduced with LPC213x/01 0xE003 4030 and ADC1: AD1STAT -
devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231 0xE006 0030). . . . . . . . . . . . . . . . . . . . . . . . 235
18.2 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . 231 18.4.5 A/D Interrupt Enable Register (ADINTEN, ADC0:
AD0INTEN - 0xE003 400C and ADC1:
18.3 Pin description . . . . . . . . . . . . . . . . . . . . . . . . 231
AD1INTEN - 0xE006 000C) . . . . . . . . . . . . . 236
18.4 Register description . . . . . . . . . . . . . . . . . . . 232 18.4.6 A/D Data Registers (ADDR0 to ADDR7, ADC0:
18.4.1 A/D Control Register (AD0CR - 0xE003 4000 and AD0DR0 to AD0DR7 - 0xE003 4010 to
AD1CR - 0xE006 0000) . . . . . . . . . . . . . . . . 233 0xE003 402C and ADC1: AD1DR0 to AD1DR7-
18.4.2 A/D Global Data Register (AD0GDR - 0xE006 0010 to 0xE006 402C) . . . . . . . . . . 237
0xE003 4004 and AD1GDR - 0xE006 0004) 234
18.5 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
18.4.3 A/D Global Start Register (ADGSR -
18.5.1 Hardware-triggered conversion . . . . . . . . . . 238
0xE003 4008) . . . . . . . . . . . . . . . . . . . . . . . . 235
18.5.2 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
18.5.3 Accuracy vs. digital receiver . . . . . . . . . . . . 238
18.5.4 Suggested ADC interface . . . . . . . . . . . . . . 238

Chapter 19: LPC213x DAC

19.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239 19.3 DAC Register (DACR - 0xE006 C000) . . . . . 239
19.2 Pin description . . . . . . . . . . . . . . . . . . . . . . . . 239 19.4 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240

Chapter 20: LPC213x Flash memory

20.1 Flash boot loader . . . . . . . . . . . . . . . . . . . . . . 241 20.4.6 ISP data format . . . . . . . . . . . . . . . . . . . . . . 243
20.2 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241 20.4.7 ISP flow control . . . . . . . . . . . . . . . . . . . . . . 243
20.3 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . 241 20.4.8 ISP command abort . . . . . . . . . . . . . . . . . . . 244
20.4.9 Interrupts during ISP . . . . . . . . . . . . . . . . . . 244
20.4 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
20.4.10 Interrupts during IAP . . . . . . . . . . . . . . . . . . 244
20.4.1 Memory map after any reset. . . . . . . . . . . . . 241 20.4.11 RAM used by ISP command handler. . . . . . 244
20.4.2 Criterion for valid user code . . . . . . . . . . . . . 242 20.4.12 RAM used by IAP command handler. . . . . . 244
20.4.3 Communication protocol . . . . . . . . . . . . . . . . 243 20.4.13 RAM used by RealMonitor . . . . . . . . . . . . . . 244
20.4.4 ISP command format . . . . . . . . . . . . . . . . . . 243 20.4.14 Boot process flowchart. . . . . . . . . . . . . . . . . 245
20.4.5 ISP response format . . . . . . . . . . . . . . . . . . . 243
UM10120 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved.

User manual Rev. 3 — 4 October 2010 295 of 297

NXP Semiconductors UM10120
Chapter 24: Supplementary information

20.5 Sector numbers . . . . . . . . . . . . . . . . . . . . . . . 246 20.8.10 Blank check sector(s) <sector number> <end
20.6 Flash content protection mechanism . . . . . 247 sector number> . . . . . . . . . . . . . . . . . . . . . . 255
20.7 Code Read Protection (CRP) . . . . . . . . . . . . 248 20.8.11 Read Part Identification number . . . . . . . . . 255
20.8.12 Read Boot code version number . . . . . . . . . 256
20.7.1 Bootloader options . . . . . . . . . . . . . . . . . . . . 249
20.8.13 Compare <address1> <address2>
20.8 ISP commands . . . . . . . . . . . . . . . . . . . . . . . . 250 <no of bytes> . . . . . . . . . . . . . . . . . . . . . . . . 256
20.8.1 Unlock <unlock code> . . . . . . . . . . . . . . . . . 250 20.8.14 ISP Return codes. . . . . . . . . . . . . . . . . . . . . 257
20.8.2 Set Baud Rate <baud rate> <stop bit> . . . . . 251
20.9 IAP Commands . . . . . . . . . . . . . . . . . . . . . . . 257
20.8.3 Echo <setting> . . . . . . . . . . . . . . . . . . . . . . . 251
20.9.1 Prepare sector(s) for write operation . . . . . . 259
20.8.4 Write to RAM <start address>
20.9.2 Copy RAM to Flash . . . . . . . . . . . . . . . . . . . 260
<number of bytes> . . . . . . . . . . . . . . . . . . . . 252
20.9.3 Erase sector(s). . . . . . . . . . . . . . . . . . . . . . . 261
20.8.5 Read memory <address> <no. of bytes> . . . 252
20.9.4 Blank check sector(s). . . . . . . . . . . . . . . . . . 261
20.8.6 Prepare sector(s) for write operation <start sector
20.9.5 Read Part Identification number . . . . . . . . . 261
number> <end sector number> . . . . . . . . . . 253
20.9.6 Read Boot code version number . . . . . . . . . 262
20.8.7 Copy RAM to Flash <Flash address> <RAM
20.9.7 Compare <address1> <address2>
address> <no of bytes> . . . . . . . . . . . . . . . . 254
<no of bytes> . . . . . . . . . . . . . . . . . . . . . . . . 262
20.8.8 Go <address> <mode>. . . . . . . . . . . . . . . . . 254
20.9.8 Reinvoke ISP . . . . . . . . . . . . . . . . . . . . . . . . 262
20.8.9 Erase sector(s) <start sector number> <end
20.9.9 IAP Status codes . . . . . . . . . . . . . . . . . . . . . 263
sector number>. . . . . . . . . . . . . . . . . . . . . . . 255
20.10 JTAG Flash programming interface . . . . . . 263

Chapter 21: LPC213x EmbeddedTrace

21.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264 21.4 Pin description . . . . . . . . . . . . . . . . . . . . . . . 265
21.2 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . 264 21.5 Reset state of multiplexed pins . . . . . . . . . . 265
21.3 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . 264 21.6 Register description . . . . . . . . . . . . . . . . . . . 266
21.3.1 ETM configuration . . . . . . . . . . . . . . . . . . . . 264 21.7 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . 267

Chapter 22: LPC213x EmbeddedICE

22.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 268 22.5 Reset state of multiplexed pins . . . . . . . . . . 269
22.2 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . 268 22.6 Register description . . . . . . . . . . . . . . . . . . . 270
22.3 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . 268 22.7 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . 270
22.4 Pin description . . . . . . . . . . . . . . . . . . . . . . . . 269

Chapter 23: LPC213x RealMonitor

23.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271 23.4.6 Data Abort mode . . . . . . . . . . . . . . . . . . . . . 275
23.2 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . 271 23.4.7 User/System mode . . . . . . . . . . . . . . . . . . . 275
23.3 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . 271 23.4.8 FIQ mode . . . . . . . . . . . . . . . . . . . . . . . . . . . 275
23.4.9 Handling exceptions. . . . . . . . . . . . . . . . . . . 275
23.3.1 RealMonitor components . . . . . . . . . . . . . . . 272
23.4.10 RealMonitor exception handling. . . . . . . . . . 275
23.3.2 RMHost. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272
23.4.11 RMTarget initialization . . . . . . . . . . . . . . . . . 276
23.3.3 RMTarget . . . . . . . . . . . . . . . . . . . . . . . . . . . 272
23.4.12 Code example . . . . . . . . . . . . . . . . . . . . . . . 276
23.3.4 How RealMonitor works . . . . . . . . . . . . . . . . 273
23.5 RealMonitor build options . . . . . . . . . . . . . . 279
23.4 How to enable Realmonitor. . . . . . . . . . . . . . 274
23.4.1 Adding stacks . . . . . . . . . . . . . . . . . . . . . . . . 274
23.4.2 IRQ mode . . . . . . . . . . . . . . . . . . . . . . . . . . . 274
23.4.3 Undef mode . . . . . . . . . . . . . . . . . . . . . . . . . 274
23.4.4 SVC mode . . . . . . . . . . . . . . . . . . . . . . . . . . 274
23.4.5 Prefetch Abort mode. . . . . . . . . . . . . . . . . . . 275

continued >>

User manual Rev. 3 — 4 October 2010 296 of 297

NXP Semiconductors UM10120
Chapter 24: Supplementary information

Chapter 24: Supplementary information

24.1 Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . 282 24.3 Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284
24.2 Legal information. . . . . . . . . . . . . . . . . . . . . . 283 24.4 Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289
24.2.1 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . 283 24.5 Contents. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 290
24.2.2 Disclaimers . . . . . . . . . . . . . . . . . . . . . . . . . . 283
24.2.3 Trademarks. . . . . . . . . . . . . . . . . . . . . . . . . . 283

297 Please be aware that important notices concerning this document and the product(s)
described herein, have been included in section ‘Legal information’.

For more information, please visit: http://www.nxp.com
For sales office addresses, please send an email to: salesaddresses@nxp.com
Date of release: 4 October 2010
Document identifier: UM10120

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