TMS320C672x DSP Software-Programmable

Phase-Locked Loop (PLL) Controller

Reference Guide

Literature Number: SPRU879A

May 2005
2 SPRU879A – May 2005
 Contents

Preface ............................................................................................................................... 5
1 Overview .................................................................................................................... 7
2 Functional Description................................................................................................. 9
2.1 Multiplier and Dividers .............................................................................................. 9
2.2 Reset Controller ..................................................................................................... 9
3 Configuration ............................................................................................................ 11
3.1 Initialization ......................................................................................................... 11
3.2 Changing Divider/Multiplier Ratio............................................................................... 12
3.3 PLL Power Down .................................................................................................. 13
3.4 PLL Wake Up ...................................................................................................... 13
3.5 Oscillator Power Down ........................................................................................... 13
4 Registers .................................................................................................................. 14
4.1 PLL Controller Peripheral Identification Register (PLLPID) .................................................. 14
4.2 PLL Control/Status Register (PLLCSR) ........................................................................ 15
4.3 PLL Multiplier Control Register (PLLM) ........................................................................ 16
4.4 PLL Controller Divider Registers (PLLDIV0-PLLDIV3) ....................................................... 17
4.5 PLL Controller Command Register (PLLCMD) ................................................................ 18
4.6 PLL Controller Status Register (PLLSTAT) .................................................................... 19
4.7 PLL Controller Clock Align Control Register (ALNCTL) ...................................................... 20
4.8 Clock Enable Control Register (CKEN) ........................................................................ 21
4.9 Clock Status Register (CKSTAT) ............................................................................... 22
4.10 SYSCLK Status Register (SYSTAT) ............................................................................ 23
Appendix A Board Connections to Select CLKIN or OSCIN as Reference Clock Source ........... 24

SPRU879A – May 2005 Table of Contents 3

 List of Figures
1 PLL Controller Block Diagram.............................................................................................. 8
2 Reset Controller Lengthening the Internal Reset Signal .............................................................. 10
3 Clock Ratio Change and Alignment with GO Operation .............................................................. 12
4 PLL Controller Peripheral Identification Register (PLLPID) [Offset 000h] .......................................... 14
5 PLL Control/Status Register (PLLCSR) [Offset 100h] ................................................................. 15
6 PLL Multiplier Control Register (PLLM) [Offset 110h] ................................................................. 16
7 PLL Controller Divider Register (PLLDIVn) [Offset 114h, 118h, 11Ch, 120h]...................................... 17
8 PLL Controller Command Register (PLLCMD) [Offset 138h] ........................................................ 18
9 PLL Controller Status Register (PLLSTAT) [Offset 13Ch] ............................................................ 19
10 PLL Controller Clock Align Control Register (ALNCTL) [Offset 140h] .............................................. 20
11 Clock Enable Control Register (CKEN) [Offset 148h] ................................................................. 21
12 Clock Status Register (CKSTAT) [Offset 14Ch] ........................................................................ 22
13 SYSCLK Status Register (SYSTAT) [Offset 150h] .................................................................... 23
A-1 CLKIN Pin Used as Reference Clock Source .......................................................................... 24
A-2 OSCIN Pin Used as Reference Clock Source.......................................................................... 25

List of Tables
1 PLL Controller Registers .................................................................................................. 14

2 PLL Controller Peripheral Identification Register (PLLPID) Field Descriptions .................................... 14

3 PLL Control/Status Register (PLLCSR) Field Descriptions ........................................................... 15

4 PLL Multiplier Control Register (PLLM) Field Descriptions ........................................................... 16

5 PLL Controller Divider Register (PLLDIVn) Field Descriptions ....................................................... 17

6 PLL Controller Command Register (PLLCMD) Field Descriptions................................................... 18

7 PLL Controller Status Register (PLLSTAT) Field Descriptions....................................................... 19

8 PLL Controller Clock Align Control Register (ALNCTL) Field Descriptions ........................................ 20

9 Clock Enable Control Register (CKEN) Field Descriptions ........................................................... 21

10 Clock Status Register (CKSTAT) Field Descriptions .................................................................. 22

11 SYSCLK Status Register (SYSTAT) Field Descriptions .............................................................. 23

4 List of Figures SPRU879A – May 2005

 Preface
SPRU879A – May 2005

Read This First

About This Manual

This document describes the operation of the software-programmable phase-locked loop (PLL) controller
in the TMS320C672x™ digital signal processors (DSPs) of the TMS320C6000™ DSP family. Refer to the
device-specific data manual to determine if the PLL controller is used on a particular device.

Notational Conventions
This document uses the following conventions.
• Hexadecimal numbers are shown with the suffix h. For example, the following number is 40
hexadecimal (decimal 64): 40h.
• Registers in this document are shown in figures and described in tables.
– Each register figure shows a rectangle divided into fields that represent the fields of the register.
Each field is labeled with its bit name, its beginning and ending bit numbers above, and its
read/write properties below. A legend explains the notation used for the properties.
– Reserved bits in a register figure designate a bit that is used for future device expansion.

Related Documentation From Texas Instruments

The following documents describe the C6000™ devices and related support tools. Copies of these
documents are available on the Internet at www.ti.com. Tip: Enter the literature number in the search box
provided at www.ti.com.
The current documentation that describes the C6000 devices, related peripherals, and other technical
collateral, is available in the C6000 DSP product folder at: www.ti.com/c6000.
TMS320C67x/C67x+ DSP CPU and Instruction Set Reference Guide (literature number SPRU733)
describes the TMS320C67x™ CPU architecture, instruction set, pipeline, and interrupts for these digital
signal processors.
TMS320C672x DSP Peripherals Overview Reference Guide (literature number SPRU723) describes
the peripherals available on the TMS320C672x™ DSPs.
TMS320C6000 Technical Brief (literature number SPRU197) gives an introduction to the TMS320C62x™
and TMS320C67x™ DSPs, development tools, and third-party support.
TMS320C6000 Programmer's Guide (literature number SPRU198) describes ways to optimize C and
assembly code for the TMS320C6000™ DSPs and includes application program examples.
TMS320C6000 Code Composer Studio Tutorial (literature number SPRU301) introduces the Code
Composer Studio™ integrated development environment and software tools.
Code Composer Studio Application Programming Interface Reference Guide (literature number
SPRU321) describes the Code Composer Studio™ application programming interface (API), which allows
you to program custom plug-ins for Code Composer.

SPRU879A – May 2005 Preface 5

 www.ti.com

Related Documentation From Texas Instruments

Trademarks
TMS320C672x, TMS320C6000, C6000, TMS320C67x, TMS320C62x, Code Composer Studio, C672x are
trademarks of Texas Instruments.

6 Read This First SPRU879A – May 2005

 Reference Guide
SPRU879A – May 2005

Phase-Locked Loop (PLL) Controller

This document describes the operation of the software-programmable phase-locked

loop (PLL) controller in the TMS320C672x™ digital signal processors (DSP).

1 Overview
The PLL controller (Figure 1) features software-configurable PLL multiplier controller (PLLM), dividers (D0,
D1, D2, and D3), and reset controller. The PLL controller accepts an input clock from the CLKIN pin or
from the on-chip oscillator output signal OSCIN. The PLL controller offers flexibility and convenience by
way of software-configurable multiplier and dividers to modify the input signal internally. The resulting
clock outputs are passed to the DSP core, peripherals, and other modules inside the DSP.
• The input reference clocks to the PLL controller:
– CLKIN: input signal from external oscillator (3.3V)
– OSCIN: output signal from on-chip oscillator (1.2V)
• The resulting output clocks from the PLL controller:
– AUXCLK: internal clock output signal directly from CLKIN or OSCIN.
– SYSCLK1: internal clock output of divider D1.
– SYSCLK2: internal clock output of divider D2.
– SYSCLK3: internal clock output of divider D3.
Refer to your device-specific data manual on how these inputs and outputs of the PLL controller are used.

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Overview

Figure 1. PLL Controller Block Diagram

PLL controller
(A)

CLKIN Divider D0
÷1, ÷2,...÷32 PLL(B) PLLOUT
OSCIN

PLLM
x4 − x25

0 1 PLLEN

Reset Divider D1 Divider D2 Divider D3

controller ÷1, ÷2,...÷32 ÷1, ÷2,...÷32 ÷1, ÷2,...÷32

AUXCLK SYSCLK1 SYSCLK2 SYSCLK3

A See Appendix A for details on how to select between CLKIN and OSCIN.
B See the device-specific data manual for more detail about the PLL.

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Functional Description

2 Functional Description
The following sections describe the multiplier, dividers, and reset controller in the PLL controller.

2.1 Multiplier and Dividers

The PLL controller is capable of programming the PLL through the PLL multiplier control register (PLLM)
from a ×4 to ×25 multiplier rate. The clock dividers (D0, D1, D2, and D3) are programmable from a ÷1 to
÷32 divider ratio and may be disabled. When a clock divider is disabled, no clock is output from that clock
divider. A divider only outputs a clock when it is enabled in the corresponding PLLDIVn register.
The input reference clock (either CLKIN or OSCIN) is directly output as the auxiliary clock (AUXCLK) for
use by some peripherals. For example, the multichannel audio serial port (McASP) can use AUXCLK to
generate audio clocks.
The divider D0 and the PLL may also be bypassed. The PLL enable bit (PLLEN) in the PLL control/status
register (PLLCSR) determines the PLL controller mode. When PLLEN = 1, PLL mode, D0 and PLL are
used; when PLLEN = 0, bypass mode, D0 and PLL are bypassed and the input reference clock is directly
input to dividers D1, D2, and D3. On the C672x™ DSP, the PLL defaults to bypass mode (PLLEN = 0).
When in PLL mode (PLLEN = 1), the input reference clock is supplied to divider D0. Divider D0 must be
enabled (D0EN = 1) in PLL mode. When divider D0 is enabled, the input reference clock is divided down
by the value in the PLL divider ratio bits (RATIO) in PLLDIV0. The output from divider D0 is input to the
PLL. The PLL multiplies the clock by the value in the PLL multiplier bits (PLLM) in the PLL multiplier
control register (PLLM). The output from the PLL (PLLOUT) is input to dividers D1, D2, and D3.
When enabled (DnEN = 1), the dividers D1, D2, and D3 divide-down by the RATIO value in PLLDIVn the
output clock of the PLL. The output clocks of dividers D1, D2, and D3 have 50% duty cycle and are
SYSCLK1, SYSCLK2, and SYSCLK3, respectively.

2.2 Reset Controller

At power up, the device RESET signal may not be asserted long enough to wait for the on-chip or off-chip
oscillator to stabilize. This means the input reference clock (either CLKIN or OSCIN) may not be a stable
clock when a device RESET signal is deasserted high. After RESET is deasserted, the reset controller
lengthens the asynchronous internal reset signal to ensure that the input clock source is stable. The reset
controller resides within the PLL controller and the main function is to internally lengthen the reset signal
from the RESET input pin until the input clock source is stable (after 4096 CLKIN or OSCIN cycles). This
is to ensure that the rest of the device will see the internal reset deasserted only after the input clock is
stabilized. Figure 2 shows the lengthening of the internal reset signal.
The PLL controller multiplier and dividers are bypassed when the internal reset signal is low. The
frequency of all clock outputs of the PLL controller (AUXCLK, SYSCLK1, SYSCLK2, and SYSCLK3) are
fixed to the input reference clock (CLKIN or OSCIN) divided by 8. After 4096 CLKIN or OSCIN cycles, the
reset controller brings the device out of reset and sets the oscillator input stable bit (STABLE) in the PLL
control/status register (PLLCSR). The dividers are used after this point and are set to their default divide
ratio.
Values are latched into the registers at the rising edge of RESET.

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Functional Description

Figure 2. Reset Controller Lengthening the Internal Reset Signal

Input clock not yet
1 2 stabilized. Internal 3
reset stays asserted.
Core power stabilized Register values latched. Device released from reset
1.2 V CVDD

RESET pin

N input clock cycles†

Asynchronous
internal reset

Clock may not stabilize yet

Crystal
Clock now stable,
STABLE bit asserted
Input reference Invalid
clock(A)

Dividers now used with default

Output clocks are input reference clock/8† divide ratio. Output clocks are
with dividers in bypass mode divider output.
PLL controller
output Invalid
clocks(B)
A N = 4096 × input reference clock (CLKIN or OSCIN cycles)
B Output clocks include AUXCLK, SYSCLK1, SYSCLK2, and SYSCLK3 at the PLL controller boundary. Refer to the
device-specific data manual for clock behavior at the device pins.

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Configuration

3 Configuration
The following sections provide procedures for initialization, power down, and wake up of the PLL
controller.

3.1 Initialization
The PLL and PLL controller are to be initialized by software after reset. The PLL controller registers should
be modified only by the CPU or via emulation. The HPI should not be used to directly access the PLL
controller registers. The initialization of the PLL controller should be performed as soon as possible at the
beginning of the program, before initializing any peripherals. Upon device reset, one of the following two
software initialization procedures must be done to properly set up the PLL and PLL controller.

3.1.1 Initialization to PLL Mode (PLLEN = 1)

This section shows the initialization sequence, if the system intends to use divider D0 and PLL. This
section also shows when you should program the multipliers and dividers, if needed.
1. In PLLCSR, write PLLEN = 0 (bypass mode).
2. Wait 4 cycles of the slowest of PLLOUT or reference clock source (CLKIN or OSCIN).
3. In PLLCSR, write PLLRST = 1 (PLL is reset).
4. If necessary, program PLLDIV0 and PLLM.
5. If necessary, program PLLDIV1-n. Note that you must apply the GO operation to change these dividers
to new ratios. See Section 3.2.1.
6. Wait for PLL to properly reset. See device-specific data manual for PLL reset time.
7. In PLLCSR, write PLLRST = 0 to bring PLL out of reset.
8. Wait for PLL to lock. See device-specific data manual for PLL lock time.
9. In PLLCSR, write PLLEN = 1 to enable PLL mode.
Steps 1, 2, and 3 are required when PLLEN and PLLRST bits are not already 0 and 1, respectively. These
steps are not required when the device is coming out of reset (by default, PLLEN and PLLRST bits are 0
and 1, respectively).

3.1.2 Initialization to Bypass Mode (PLLEN = 0)

This section shows the initialization sequence, if the system intends to bypass divider D0 and PLL. This
section also shows when you should program the multipliers and dividers, if needed.
1. In PLLCSR, write PLLEN = 0 (bypass mode).
2. Wait 4 cycles of the slowest of PLLOUT or reference clock source (CLKIN or OSCIN).
3. In PLLCSR, write PLLRST = 1 (PLL is reset).
4. It is not necessary to program PLLDIV0 and PLLM.
5. If necessary, program PLLDIV1-n. Note that you must apply the GO operation to change these dividers
to new ratios. See Section 3.2.1.
Steps 1, 2, and 3 are required when PLLEN and PLLRST bits are not already 0 and 1, respectively. These
steps are not required when the device is coming out of reset (by default, PLLEN and PLLRST bits are 0
and 1, respectively).

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Configuration
3.2 Changing Divider/Multiplier Ratio
This section discusses how to change the various divider/multiplier ratios.

3.2.1 Divider n (D1 to Dn) and GO Operation

The GO operation is required to change the divider ratios of D1 to Dn. Section 3.2.1.1 discusses the GO
operation. Section 3.2.1.2 gives the software steps required to change the divider ratios.

3.2.1.1 GO Operation
Writes to the RATIO field in PLLDIV1-PLLDIV3 do not change the dividers’ actual divide ratios
immediately. The PLLDIVn dividers only change to the new RATIO rates during a GO operation. This
section discusses the GO operation and how the SYSCLKs are aligned.
The PLL controller clock align control register (ALNCTL) determines which SYSCLKs must be aligned.
Before a GO operation, you must program ALNCTL according to the device-specific data manual
requirement so that the appropriate clocks are aligned during the GO operation. All SYSCLKs must be
aligned; therefore, the ALNn bits in ALNCTL should always be set to 1 before a GO operation.
A GO operation is initiated by setting the GOSET bit in PLLCMD to 1. During a GO operation:
• Any SYSCLKn with the corresponding ALNn bit in ALNCTL set to 1 is paused at the low edge. Then
the PLL controller restarts all these SYSCLKs simultaneously, aligned at the rising edge. When the
SYSCLKs are restarted, SYSCLKn toggles at the rate programmed in the RATIO field in PLLDIVn.
• Any SYSCLKn with the corresponding ALNn bit in ALNCTL cleared to 0 remains free-running during a
GO operation. SYSCLKn is not modified to the new RATIO rate in PLLDIVn. SYSCLKn is not aligned
to other SYSCLKs.
• The GOSTAT bit in PLLSTAT is set to 1 throughout the duration of a GO operation.
Figure 3 shows how the clocks are rising-edge aligned during a GO operation. Even though SYSCLK3
ratio remains the same, you must still program ALN3 = 1 in ALNCTL so that during the GO operation the
PLL controller aligns SYSCLK3 to SYSCLK1 and SYSCLK2.

Figure 3. Clock Ratio Change and Alignment with GO Operation

PLLDIV.RATIO GO operation: End of GO operation. GOSTAT automatically
modified, but GOSET set, clears to 0 to indicate completion of clock rate
SYSCLKn not GOSTAT change
changed yet changed to 1
PLLSTAT.
GOSTAT

SYSCLK1
/1 to /2,
set ALN1=1
SYSCLK2
/2 to /4,
set ALN2=1
SYSCLK3
/3 to /3,
set ALN3=1
All SYSCLKs rising−edge aligned

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Configuration
3.2.1.2 Software Steps to Modify PLLDIVn Ratios
Perform the following steps to modify PLLDIVn.
1. Check that the GOSTAT bit in PLLSTAT is cleared to 0 to show that no GO operation is currently in
progress.
2. Program the RATIO field in PLLDIVn to the desired new divide-down rate.
3. Set the ALN1-3 bits in ALNCTL to 1 so that SYSCLK1-3 are aligned after the GO operation.
4. Set the GOSET bit in PLLCMD to 1 to initiate the GO operation to change the divide values and align
SYSCLK1-3.
5. Read the GOSTAT bit in PLLSTAT to make sure the bit goes back to 0 to indicate that the GO
operation has completed.

3.2.2 Divider 0 and PLL Multiplier (PLLM)

To change the values of D0 or PLLM, the PLL controller must first be placed in bypass mode. Perform the
following steps to modify D0 or PLLM ratios.
1. In PLLCSR, write PLLEN = 0 to place the PLL in bypass mode.
2. Modify D0 and/or PLLM ratios
3. Wait for PLL to relock.
4. In PLLCSR, write PLLEN = 1 to switch from bypass mode to PLL mode.

3.3 PLL Power Down

The PLL may be powered down, in which case the PLL controller is in bypass mode and the DSP runs
from a divided down version of the input reference clock. The DSP is still able to respond to events
because it is still being clocked by the bypass clock (directly from CLKIN or OSCIN), although at a lower
frequency.
Perform the following procedure to power down the PLL.
1. In PLLCSR, write PLLEN = 0 (bypass mode).
2. Wait 4 cycles of the slowest of PLLOUT or reference clock source (CLKIN or OSCIN).
3. In PLLCSR, write PLLPWRDN = 1 to power down the PLL.

3.4 PLL Wake Up

Perform the following procedure to wake up the PLL from its power-down mode.
1. Check to be sure PLL is already in bypass mode (PLLEN = 0).
2. In PLLCSR, write PLLPWRDN = 0 to wake up the PLL.
3. Follow the PLL reset sequence in Section 3.1.1 (steps 3 to 9) to reset the PLL. Wait for the PLL to lock
and to switch from bypass to PLL mode.

3.5 Oscillator Power Down

Perform the following procedure to power down the oscillator.
1. In PLLCSR, write PLLEN = 0 (bypass mode).
2. Wait 4 cycles of the slowest of PLLOUT or reference clock source (CLKIN or OSCIN).
3. (Optional) Because the PLL is not used, you may place the PLL in power-down mode by writing
PLLPWRDN = 1 in PLLCSR.
4. In PLLCSR, write OSCPWRDN = 1 to power down the oscillator.
A chip reset is required to wake up the device from oscillator power-down mode.

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Registers

4 Registers
The PLL controller registers configure the operation of the PLL controller. The PLL controller registers are
listed in Table 1. See the device-specific data manual for the memory address of these registers. All other
register offset addresses not listed in Table 1 should be considerd as reserved locations and the register
contents should not be modified.

Table 1. PLL Controller Registers

Offset Acronym Register Description Section
000h PLLPID PLL controller peripheral identification register Section 4.1
100h PLLCSR PLL control/status register Section 4.2
110h PLLM PLL multiplier control register Section 4.3
114h PLLDIV0 PLL controller divider register 0 Section 4.4
118h PLLDIV1 PLL controller divider register 1 Section 4.4
11Ch PLLDIV2 PLL controller divider register 2 Section 4.4
120h PLLDIV3 PLL controller divider register 3 Section 4.4
138h PLLCMD PLL controller command register Section 4.5
13Ch PLLSTAT PLL controller status register Section 4.6
140h ALNCTL PLL controller clock align control register Section 4.7
148h CKEN Clock enable control register Section 4.8
14Ch CKSTAT Clock status register Section 4.9
150h SYSTAT SYSCLK status register Section 4.10

4.1 PLL Controller Peripheral Identification Register (PLLPID)

The PLL controller peripheral identification register (PLLPID) contains identification code for the PLL
controller. PLLPID is shown in Figure 4 and described in Table 2.

Figure 4. PLL Controller Peripheral Identification Register (PLLPID) [Offset 000h]

31 24 23 16
Reserved TYPE
R-0 R-01h

15 8 7 0
CLASS REV
R-08h R-01h
LEGEND: R = Read only; -n = value after reset

Table 2. PLL Controller Peripheral Identification Register (PLLPID) Field Descriptions

Bit Field Value Description
31-24 Reserved 0 Reserved
23-16 TYPE Identifies type of peripheral
01h PLL controller
15-8 CLASS Identifies class of peripheral
08h Serial port
7-0 REV Identifies revision of peripheral.
01h Current revision of peripheral.

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Registers

4.2 PLL Control/Status Register (PLLCSR)

The PLL control/status register (PLLCSR) is shown in Figure 5 and described in Table 3.

Figure 5. PLL Control/Status Register (PLLCSR) [Offset 100h]

31 16
Reserved
R-0

15 7 6 5 4 3 2 1 0
Reserved STABLE Rsvd PLLPWRDN PLLRST OSCPWRDN Rsvd PLLEN
R-0 R-1 R/W-0 R/W-1 R/W-1 R/W-0 R/W-0 R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset

Table 3. PLL Control/Status Register (PLLCSR) Field Descriptions

Bit Field Value Description
31-7 Reserved 0 Reserved. The reserved bit location is always read as 0. A value written to this field has no effect.
6 STABLE Oscillator input stable bit. Indicates if the OSCIN/CLKIN input has stabilized. The STABLE bit is set to 1
after the reset controller counts 4096 OSCIN or CLKIN input clock cycles after the RESET signal is
asserted high. It is assumed that the OSCIN/CLKIN input is stabilized after this number of cycles.
0 OSCIN/CLKIN input is not yet stable. Oscillator counter is not finished counting.
1 Oscillator counter is done counting and OSCIN/CLKIN input is assumed to be stable.
5 Reserved 0 Reserved. The reserved bit location is always read as 0. Always write a 0 to this location.
4 PLLPWRDN PLL power-down mode select bit.
0 PLL is operational.
1 PLL is placed in power-down state.
3 PLLRST PLL reset bit.
0 PLL reset is released.
1 PLL reset is asserted.
2 OSCPWRDN Oscillator power-down mode command bit.
0 No effect. Write of 0 clears bit to 0.
1 Oscillator power-down command. Write of 1 causes oscillator power-down command. Once set,
OSCPWRDN remains set but further writes of 1 can reinitiate the oscillator power-down command.
1 Reserved 0 Reserved. The reserved bit location is always read as 0. Always write a 0 to this location.
0 PLLEN PLL enable bit.
0 Bypass mode. Divider D0 and PLL are bypassed. SYSCLK1/SYSCLK2/SYSCLK3 are divided down
directly from input reference clock.
1 PLL mode. Divider D0 and PLL are not bypassed. PLL output path is enabled.
SYSCLK1/SYSCLK2/SYSCLK3 are divided down from PLL output.

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Registers
4.3 PLL Multiplier Control Register (PLLM)
The PLL multiplier control register (PLLM) is shown in Figure 6 and described in Table 4. The PLLM
defines the input reference clock frequency multiplier in conjunction with the PLL divider ratio bits (RATIO)
in the PLL controller divider 0 register (PLLDIV0).

Figure 6. PLL Multiplier Control Register (PLLM) [Offset 110h]

31 16
Reserved
R-0

15 5 4 0
Reserved PLLM
R-0 R/W-Dh
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset

Table 4. PLL Multiplier Control Register (PLLM) Field Descriptions

Bit Field Value Description
31-5 Reserved 0 Reserved. The reserved bit location is always read as 0. A value written to this field has no effect.
4-0 PLLM 0-1Fh PLL multiplier bits. Defines the frequency multiplier of the input reference clock in conjunction with
the PLL divider ratio bits (RATIO) in PLLDIV0.
0-3h Reserved
4h ×4 multiplier rate
5h ×5 multiplier rate
6h-19h ×6 multiplier rate to ×25 multiplier rate
1Ah-1Fh Reserved

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Registers
4.4 PLL Controller Divider Registers (PLLDIV0-PLLDIV3)
The PLL controller divider register (PLLDIV0-PLLDIV3) is shown in Figure 7 and described in Table 5.

Figure 7. PLL Controller Divider Register (PLLDIVn) [Offset 114h, 118h, 11Ch, 120h]
31 16
Reserved
R-0

15 14 5 4 0
DnEN Reserved RATIO(A)
R/W-1 R-0 R/W-n
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
A For DIV0 and DIV1, the default value is 0h (÷1); for DIV2, the default value is 1h (÷2); for DIV3, the default value is 2h (÷3).

Table 5. PLL Controller Divider Register (PLLDIVn) Field Descriptions

Bit Field Value Description
31-16 Reserved 0 Reserved. The reserved bit location is always read as 0. A value written to this field has no effect.
15 DnEN Divider Dn enable bit.
0 Divider n is disabled. No clock output.
1 Divider n is enabled.
14-5 Reserved 0 Reserved. The reserved bit location is always read as 0. A value written to this field has no effect.
4-0 RATIO 0-1Fh Divider ratio bits.
0 ÷1. Divide frequency by 1.
1h ÷2. Divide frequency by 2.
2h ÷3. Divide frequency by 3.
3h-1Fh ÷4 to ÷32. Divide frequency by 4 to divide frequency by 32.

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Registers
4.5 PLL Controller Command Register (PLLCMD)
The PLL controller command register (PLLCMD) contains the command bit for GO operation. PLLCMD is
shown in Figure 8 and described in Table 6.

Figure 8. PLL Controller Command Register (PLLCMD) [Offset 138h]

31 16
Reserved
R-0

15 1 0
Reserved GOSET
R-0 R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset

Table 6. PLL Controller Command Register (PLLCMD) Field Descriptions

Bit Field Value Description
31-1 Reserved 0 Reserved. The reserved bit location is always read as 0. A value written to this field has no effect.
0 GOSET GO operation command for SYSCLK rate change and phase alignment.
0 No effect. Write of 0 clears bit to 0.
1 Initiates GO operation. Write of 1 initiates GO operation. Once set, GOSET remains set but further
writes of 1 can reinitiate the GO operation.

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Registers
4.6 PLL Controller Status Register (PLLSTAT)
The PLL controller status register (PLLSTAT) shows the PLL controller status. PLLSTAT is shown in
Figure 9 and described in Table 7.

Figure 9. PLL Controller Status Register (PLLSTAT) [Offset 13Ch]

31 16
Reserved
R-0

15 1 0
Reserved GOSTAT
R-0 R-0
LEGEND: R = Read only; -n = value after reset

Table 7. PLL Controller Status Register (PLLSTAT) Field Descriptions

Bit Field Value Description
31-1 Reserved 0 Reserved. The reserved bit location is always read as 0. A value written to this field has no effect.
0 GOSTAT GO operation status.
0 GO operation is not in progress. SYSCLK divide ratios are not being changed.
1 GO operation is in progress. SYSCLK divide ratios are being changed and SYSCLKs are being aligned.

SPRU879A – May 2005 Phase-Locked Loop (PLL) Controller 19

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Registers
4.7 PLL Controller Clock Align Control Register (ALNCTL)
The PLL controller clock align control register (ALNCTL) is shown in Figure 10 and described in Table 8.

Figure 10. PLL Controller Clock Align Control Register (ALNCTL) [Offset 140h]
31 16
Reserved
R-0

15 3 2 1 0
Reserved ALN3 ALN2 ALN1
R-0 R/W-0 R/W-0 R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset

Table 8. PLL Controller Clock Align Control Register (ALNCTL) Field Descriptions
Bit Field Value Description
31-3 Reserved 0 Reserved. The reserved bit location is always read as 0. A value written to this field has no effect.
2 ALN3 SYSCLK3 alignment.
0 Do not use this setting. Do not change SYSCLK3 divide ratio nor align SYSCLK3 to other SYSCLKs
during GO operation. SYSCLK3 is left free-running when the GOSET bit in PLLCMD is set to 1.
1 Use this setting. Align SYSCLK3 to other SYSCLKs selected in ALNCTL when the GOSET bit in
PLLCMD is set to 1. Change SYSCLK3 rate to the ratio programmed in the RATIO bit in PLLDIV3.
1 ALN2 SYSCLK2 alignment.
0 Do not use this setting. Do not change SYSCLK2 divide ratio nor align SYSCLK2 to other SYSCLKs
during GO operation. SYSCLK2 is left free-running when the GOSET bit in PLLCMD is set to 1.
1 Use this setting. Align SYSCLK2 to other SYSCLKs selected in ALNCTL when the GOSET bit in
PLLCMD is set to 1. Change SYSCLK2 rate to the ratio programmed in the RATIO bit in PLLDIV2.
0 ALN1 SYSCLK1 alignment.
0 Do not use this setting. Do not change SYSCLK1 divide ratio nor align SYSCLK1 to other SYSCLKs
during GO operation. SYSCLK1 is left free-running when the GOSET bit in PLLCMD is set to 1.
1 Use this setting. Align SYSCLK1 to other SYSCLKs selected in ALNCTL when the GOSET bit in
PLLCMD is set to 1. Change SYSCLK1 rate to the ratio programmed in the RATIO bit in PLLDIV1.

20 Phase-Locked Loop (PLL) Controller SPRU879A – May 2005

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Registers
4.8 Clock Enable Control Register (CKEN)
The clock enable control register (CKEN) enables/disables the PLL controller output clock, AUXCLK.
CKEN is shown in Figure 11 and described in Table 9.

Figure 11. Clock Enable Control Register (CKEN) [Offset 148h]

31 16
Reserved
R-0

15 3 2 1 0
Reserved Reserved AUXEN
R-0 R/W-1 R/W-1
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset

Table 9. Clock Enable Control Register (CKEN) Field Descriptions

Bit Field Value Description
31-3 Reserved 0 Reserved. The reserved bit location is always read as 0. A value written to this field has no effect.
2-1 Reserved 1 Reserved. The reserved bit location is always read as 1. Always write a 1 to this location.
0 AUXEN AUXCLK enable control.
0 Disable AUXCLK.
1 Enable AUXCLK.

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Registers
4.9 Clock Status Register (CKSTAT)
The clock status register (CKEN) shows the status of all PLL controller output clock, AUXCLK. CKSTAT is
shown in Figure 12 and described in Table 10.

Figure 12. Clock Status Register (CKSTAT) [Offset 14Ch]

31 16
Reserved
R-0

15 3 2 1 0
Reserved Reserved AUXON
R-0 R-1 R-1
LEGEND: R = Read only; -n = value after reset

Table 10. Clock Status Register (CKSTAT) Field Descriptions

Bit Field Value Description
31-3 Reserved 0 Reserved. The reserved bit location is always read as 0. A value written to this field has no effect.
2-1 Reserved 1 Reserved. The reserved bit location is always read as 1. A value written to this field has no effect.
0 AUXON AUXCLK on status.
0 AUXCLK is gated.
1 AUXCLK is on.

22 Phase-Locked Loop (PLL) Controller SPRU879A – May 2005

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Registers
4.10 SYSCLK Status Register (SYSTAT)
The SYSCLK status register (SYSTAT) shows the status of SYSCLK1, SYSCLK2, and SYSCLK3.
SYSTAT is shown in Figure 13 and described in Table 11.

Figure 13. SYSCLK Status Register (SYSTAT) [Offset 150h]

31 16
Reserved
R-0

15 3 2 1 0
Reserved SYS3ON SYS2ON SYS1ON
R-0 R-1 R-1 R-1
LEGEND: R = Read only; -n = value after reset

Table 11. SYSCLK Status Register (SYSTAT) Field Descriptions

Bit Field Value Description
31-3 Reserved 0 Reserved. The reserved bit location is always read as 0. A value written to this field has no effect.
2 SYS3ON SYSCLK3 on status.
0 SYSCLK3 is gated.
1 SYSCLK3 is on.
1 SYS2ON SYSCLK2 on status.
0 SYSCLK2 is gated.
1 SYSCLK2 is on.
0 SYS1ON SYSCLK1 on status.
0 SYSCLK1 is gated.
1 SYSCLK1 is on.

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Appendix A

Appendix A Board Connections to Select CLKIN or OSCIN as Reference Clock Source

The following figures show the board connections to select CLKIN or OSCIN as the reference clock
source to the PLL controller. Figure A-1 shows the case when the CLKIN pin is used as the
reference clock source. Figure A-2 shows the case when the OSCIN pin is used as the reference
clock source.

Figure A-1. CLKIN Pin Used as Reference Clock Source

External
oscillator
CLKIN
Deglitch
CVDD
OSCVDD ”0”

OSCIN
PLL
controller

OSCOUT
On−chip
Open oscillator

OSCVSS
TMS320C672x DSP

24 Board Connections to Select CLKIN or OSCIN as Reference Clock Source SPRU879A – May 2005
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Appendix A

Figure A-2. OSCIN Pin Used as Reference Clock Source

CLKIN ”0”
Deglitch

OSCVDD

OSCIN
PLL
controller

OSCOUT On−chip
oscillator

OSCVSS
TMS320C672x DSP

SPRU879A – May 2005 Board Connections to Select CLKIN or OSCIN as Reference Clock Source 25
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