MCP2515

Stand-Alone CAN Controller with SPI Interface

Features: Description
• Implements CAN V2.0B at 1 Mb/s: Microchip Technology’s MCP2515 is a stand-alone
Controller Area Network (CAN) controller that
- 0 – 8 byte length in the data field
implements the CAN specification, version 2.0B. It is
- Standard and extended data and remote capable of transmitting and receiving both standard
frames and extended data and remote frames. The MCP2515
• Receive Buffers, Masks and Filters: has two acceptance masks and six acceptance filters
- Two receive buffers with prioritized message that are used to filter out unwanted messages, thereby
storage reducing the host MCU’s overhead. The MCP2515
- Six 29-bit filters interfaces with microcontrollers (MCUs) via an industry
- Two 29-bit masks standard Serial Peripheral Interface (SPI).
• Data Byte Filtering on the First Two Data Bytes Package Types
(applies to standard data frames)
18-Lead PDIP/SOIC 1 18 VDD
• Three Transmit Buffers with Prioritization and TXCAN
Abort Features RXCAN 2 17 RESET
• High-Speed SPI Interface (10 MHz):
CLKOUT/SOF 3 16 CS
- SPI modes 0,0 and 1,1

MCP2515
TX0RTS 4 15 SO
• One-Shot mode Ensures Message Transmission
is Attempted Only One Time TX1RTS 5 14 SI

• Clock Out Pin with Programmable Prescaler: TX2RTS 6 13 SCK

- Can be used as a clock source for other OSC2 7 12 INT
device(s) 8 11 RX0BF
OSC1
• Start-of-Frame (SOF) Signal is Available for
Vss 9 10 RX1BF
Monitoring the SOF Signal:
- Can be used for time-slot-based protocols 20-LEAD TSSOP
TXCAN 1 20 VDD
and/or bus diagnostics to detect early bus 2 19
RXCAN RESET
degradation 3 18
CLKOUT/SOF CS
• Interrupt Output Pin with Selectable Enables TX0RTS 4 17 SO
MCP2515

• Buffer Full Output Pins Configurable as: TX1RTS 5 16 SI

- Interrupt output for each receive buffer NC 6 15 NC
TX2RTS 7 14 SCK
- General purpose output
OSC2 8 13 INT
• Request-to-Send (RTS) Input Pins Individually 9 12 RX0BF
OSC1
Configurable as: VSS 10 11 RX1BF
- Control pins to request transmission for each
RXCAN

transmit buffer MCP2515

TXCAN

RESET

20-Lead 4x4 QFN*

VDD

- General purpose inputs

CS

• Low-Power CMOS Technology:

20 19 18 17 16
- Operates from 2.7V – 5.5V CLKOUT 1 15 SO
- 5 mA active current (typical) TX0RTS 2 14 SI
- 1 µA standby current (typical) (Sleep mode) EP
TX1RTS 3 21 13 NC
• Temperature Ranges Supported:
NC 4 12 SCK
- Industrial (I): -40°C to +85°C
TX2RTS 5 11 INT
- Extended (E): -40°C to +125°C 6 7 8 9 10
RX1BF
RX0BF
OSC2
OSC1
GND

* Includes Exposed Thermal

Pad (EP); see Table 1-1.

 2003-2012 Microchip Technology Inc. DS21801G-page 1

MCP2515
NOTES:

DS21801G-page 2  2003-2012 Microchip Technology Inc.

 MCP2515
1.0 DEVICE OVERVIEW 1.2 Control Logic
The MCP2515 is a stand-alone CAN controller The control logic block controls the setup and operation
developed to simplify applications that require of the MCP2515 by interfacing to the other blocks in
interfacing with a CAN bus. A simple block diagram of order to pass information and control.
the MCP2515 is shown in Figure 1-1. The device Interrupt pins are provided to allow greater system
consists of three main blocks: flexibility. There is one multi-purpose interrupt pin (as
1. The CAN module, which includes the CAN well as specific interrupt pins) for each of the receive
protocol engine, masks, filters, transmit and registers that can be used to indicate a valid message
receive buffers. has been received and loaded into one of the receive
2. The control logic and registers that are used to buffers. Use of the specific interrupt pins is optional.
configure the device and its operation. The general purpose interrupt pin, as well as status
registers (accessed via the SPI interface), can also be
3. The SPI protocol block.
used to determine when a valid message has been
An example system implementation using the device is received.
shown in Figure 1-2.
Additionally, there are three pins available to initiate
1.1 CAN Module immediate transmission of a message that has been
loaded into one of the three transmit registers. Use of
The CAN module handles all functions for receiving these pins is optional, as initiating message
and transmitting messages on the CAN bus. Messages transmissions can also be accomplished by utilizing
are transmitted by first loading the appropriate control registers, accessed via the SPI interface.
message buffer and control registers. Transmission is
initiated by using control register bits via the SPI 1.3 SPI Protocol Block
interface or by using the transmit enable pins. Status
The MCU interfaces to the device via the SPI interface.
and errors can be checked by reading the appropriate
Writing to, and reading from, all registers is
registers. Any message detected on the CAN bus is
accomplished using standard SPI read and write
checked for errors and then matched against the user-
commands, in addition to specialized SPI commands.
defined filters to see if it should be moved into one of
the two receive buffers.

FIGURE 1-1: BLOCK DIAGRAM

CAN Module

RXCAN
CAN TX and RX Buffers SPI CS
Protocol Interface SCK SPI
Engine Masks and Filters Logic Bus
SI
TXCAN SO

Control Logic
OSC1
Timing
OSC2
Generation INT
CLKOUT
RX0BF
RX1BF
TX0RTS
Control TX1RTS
and
Interrupt TX2RTS
Registers RESET

 2003-2012 Microchip Technology Inc. DS21801G-page 3

MCP2515
FIGURE 1-2: EXAMPLE SYSTEM IMPLEMENTATION

Node Node Node

Controller Controller Controller

SPI SPI SPI

MCP2515 MCP2515 MCP2515

TX RX TX RX TX RX

XCVR XCVR XCVR

CANH
CANL

TABLE 1-1: PINOUT DESCRIPTION

PDIP/
TSSOP QFN I/O/P
Name SOIC Description Alternate Pin Function
Pin # Pin # Type
Pin #
TXCAN 1 1 19 O Transmit output pin to CAN bus —
RXCAN 2 2 20 I Receive input pin from CAN bus —
CLKOUT 3 3 1 O Clock output pin with programmable Start-of-Frame signal
prescaler
TX0RTS 4 4 2 I Transmit buffer TXB0 request-to-send. General purpose digital input.
100 kinternal pull-up to VDD 100 kinternal pull-up to VDD
TX1RTS 5 5 3 I Transmit buffer TXB1 request-to-send. General purpose digital input.
100 kinternal pull-up to VDD 100 kinternal pull-up to VDD
TX2RTS 6 7 5 I Transmit buffer TXB2 request-to-send. General purpose digital input.
100 kinternal pull-up to VDD 100 kinternal pull-up to VDD
OSC2 7 8 6 O Oscillator output —
OSC1 8 9 7 I Oscillator input External clock input
VSS 9 10 8 P Ground reference for logic and I/O —
pins
RX1BF 10 11 9 O Receive buffer RXB1 interrupt pin or General purpose digital output
general purpose digital output
RX0BF 11 12 10 O Receive buffer RXB0 interrupt pin or General purpose digital output
general purpose digital output
INT 12 13 11 O Interrupt output pin —
SCK 13 14 12 I Clock input pin for SPI interface —
SI 14 16 14 I Data input pin for SPI interface —
SO 15 17 15 O Data output pin for SPI interface —
CS 16 18 16 I Chip select input pin for SPI interface —
RESET 17 19 17 I Active-low device Reset input —
VDD 18 20 18 P Positive supply for logic and I/O pins —
NC — 6,15 4,13 — No internal connection —
Note: Type Identification: I = Input; O = Output; P = Power

DS21801G-page 4  2003-2012 Microchip Technology Inc.

 MCP2515
1.4 Transmit/Receive Buffers/Masks/
Filters
The MCP2515 has three transmit and two receive
buffers, two acceptance masks (one for each receive
buffer) and a total of six acceptance filters. Figure 1-3
shows a block diagram of these buffers and their
connection to the protocol engine.

FIGURE 1-3: CAN BUFFERS AND PROTOCOL ENGINE BLOCK DIAGRAM

BUFFERS Acceptance Mask

RXM1
Acceptance Filter
RXF2
A
A Acceptance Mask Acceptance Filter
c
TXB0 TXB1 TXB2 RXM0 RXF3
c c
MESSAGE

MESSAGE

MESSAGE
c Acceptance Filter Acceptance Filter e
TXREQ

TXREQ

TXREQ
TXERR

TXERR

TXERR
e RXF0 RXF4 p
MLOA

MLOA

MLOA
ABTF

ABTF

ABTF

p t
Acceptance Filter Acceptance Filter
t
RXF1 RXF5

R R
M
X Identifier Identifier X
Message A
B B
Queue B
0 1
Control
Transmit Byte Sequencer Data Field Data Field

PROTOCOL Receive REC

Error
ENGINE Counter TEC

Transmit ErrPas
Error BusOff
Counter
Transmit<7:0> Receive<7:0>
Shift<14:0>
{Transmit<5:0>, Receive<8:0>}
Comparator
Protocol
Finite SOF
State
CRC<14:0> Machine

Bit
Transmit
Timing Clock
Logic Logic Generator

TX RX
Configuration
Registers

 2003-2012 Microchip Technology Inc. DS21801G-page 5

MCP2515
1.5 CAN Protocol Engine 1.5.3 ERROR MANAGEMENT LOGIC
The CAN protocol engine combines several functional The Error Management Logic (EML) is responsible for
blocks, shown in Figure 1-4 and described below. the fault confinement of the CAN device. Its two
counters, the Receive Error Counter (REC) and the
1.5.1 PROTOCOL FINITE STATE Transmit Error Counter (TEC), are incremented and
MACHINE decremented by commands from the bit stream
processor. Based on the values of the error counters,
The heart of the engine is the Finite State Machine the CAN controller is set into the states error-active,
(FSM). The FSM is a sequencer that controls the error-passive or bus-off.
sequential data stream between the TX/RX shift
register, the CRC register and the bus line. The FSM 1.5.4 BIT TIMING LOGIC
also controls the Error Management Logic (EML) and
the parallel data stream between the TX/RX shift The Bit Timing Logic (BTL) monitors the bus line input
registers and the buffers. The FSM ensures that the and handles the bus-related bit timing according to the
processes of reception, arbitration, transmission and CAN protocol. The BTL synchronizes on a recessive-
error-signaling are performed according to the CAN to-dominant bus transition at Start-of-Frame (hard
protocol. The automatic retransmission of messages synchronization) and on any further recessive-to-
on the bus line is also handled by the FSM. dominant bus line transition if the CAN controller itself
does not transmit a dominant bit (resynchronization).
1.5.2 CYCLIC REDUNDANCY CHECK The BTL also provides programmable time segments
to compensate for the propagation delay time, phase
The Cyclic Redundancy Check register generates the shifts and to define the position of the sample point
Cyclic Redundancy Check (CRC) code, which is within the bit time. The programming of the BTL
transmitted after either the Control Field (for messages depends on the baud rate and external physical delay
with 0 data bytes) or the Data Field and is used to times.
check the CRC field of incoming messages.

FIGURE 1-4: CAN PROTOCOL ENGINE BLOCK DIAGRAM

RX TX
Bit Timing Logic Transmit Logic

SAM
REC
Sample<2:0> Receive
Error Counter
TEC
StuffReg<5:0>
Transmit
ErrPas
Majority Error Counter
Decision BusOff

BusMon

Comparator

CRC<14:0>

Protocol
FSM SOF
Comparator

Shift<14:0>
(Transmit<5:0>, Receive<7:0>)

Receive<7:0> Transmit<7:0>

RecData<7:0> TrmData<7:0>
Interface to Standard Buffer Rec/Trm Addr.

DS21801G-page 6  2003-2012 Microchip Technology Inc.

 MCP2515
2.0 CAN MESSAGE FRAMES CAN frame will win arbitration due to the assertion of a
dominant lDE bit. Also, the SRR bit in an extended
The MCP2515 supports standard data frames, CAN frame must be recessive to allow the assertion of
extended data frames and remote frames (standard a dominant RTR bit by a node that is sending a
and extended), as defined in the CAN 2.0B standard CAN remote frame.
specification.
The SRR and lDE bits are followed by the remaining
18 bits of the identifier (Extended lD) and the remote
2.1 Standard Data Frame transmission request bit.
The CAN standard data frame is shown in Figure 2-1. To enable standard and extended frames to be sent
As with all other frames, the frame begins with a Start- across a shared network, the 29-bit extended message
Of-Frame (SOF) bit, which is of the dominant state and identifier is split into 11-bit (Most Significant) and 18-bit
allows hard synchronization of all nodes. (Least Significant) sections. This split ensures that the
The SOF is followed by the arbitration field, consisting lDE bit can remain at the same bit position in both the
of 12 bits: the 11-bit identifier and the Remote standard and extended frames.
Transmission Request (RTR) bit. The RTR bit is used Following the arbitration field is the six-bit control field.
to distinguish a data frame (RTR bit dominant) from a The first two bits of this field are reserved and must be
remote frame (RTR bit recessive). dominant. The remaining four bits of the control field
Following the arbitration field is the control field, are the DLC, which specifies the number of data bytes
consisting of six bits. The first bit of this field is the contained in the message.
Identifier Extension (IDE) bit, which must be dominant The remaining portion of the frame (data field, CRC
to specify a standard frame. The following bit, Reserved field, acknowledge field, end-of-frame and
Bit Zero (RB0), is reserved and is defined as a dominant intermission) is constructed in the same way as a
bit by the CAN protocol. The remaining four bits of the standard data frame (see Section 2.1 “Standard Data
control field are the Data Length Code (DLC), which Frame”).
specifies the number of bytes of data (0-8 bytes)
contained in the message. 2.3 Remote Frame
After the control field, is the data field, which contains
Normally, data transmission is performed on an
any data bytes that are being sent, and is of the length
autonomous basis by the data source node (e.g., a
defined by the DLC (0-8 bytes).
sensor sending out a data frame). It is possible,
The Cyclic Redundancy Check (CRC) field follows the however, for a destination node to request data from
data field and is used to detect transmission errors. The the source. To accomplish this, the destination node
CRC field consists of a 15-bit CRC sequence, followed sends a remote frame with an identifier that matches
by the recessive CRC Delimiter bit. the identifier of the required data frame. The
The final field is the two-bit Acknowledge (ACK) field. appropriate data source node will then send a data
During the ACK Slot bit, the transmitting node sends frame in response to the remote frame request.
out a recessive bit. Any node that has received an There are two differences between a remote frame
error-free frame acknowledges the correct reception of (shown in Figure 2-3) and a data frame. First, the RTR
the frame by sending back a dominant bit (regardless bit is at the recessive state and, second, there is no
of whether the node is configured to accept that data field. In the event of a data frame and a remote
specific message or not). The recessive acknowledge frame with the same identifier being transmitted at the
delimiter completes the acknowledge field and may not same time, the data frame wins arbitration due to the
be overwritten by a dominant bit. dominant RTR bit following the identifier. In this way,
the node that transmitted the remote frame receives
2.2 Extended Data Frame the desired data immediately.
In the extended CAN data frame, shown in Figure 2-2,
the SOF bit is followed by the arbitration field, which
2.4 Error Frame
consists of 32 bits. The first 11 bits are the Most An error frame is generated by any node that detects a
Significant bits (MSb) (Base-lD) of the 29-bit identifier. bus error. An error frame, shown in Figure 2-4, consists
These 11 bits are followed by the Substitute Remote of two fields: an error flag field followed by an error
Request (SRR) bit, which is defined to be recessive. delimiter field. There are two types of error flag fields.
The SRR bit is followed by the lDE bit, which is The type of error flag field sent depends upon the error
recessive to denote an extended CAN frame. status of the node that detects and generates the error
It should be noted that if arbitration remains unresolved flag field.
after transmission of the first 11 bits of the identifier, and
one of the nodes involved in the arbitration is sending
a standard CAN frame (11-bit identifier), the standard

 2003-2012 Microchip Technology Inc. DS21801G-page 7

MCP2515
2.4.1 ACTIVE ERRORS 2.5 Overload Frame
If an error-active node detects a bus error, the node An overload frame, shown in Figure 2-5, has the same
interrupts transmission of the current message by format as an active-error frame. An overload frame,
generating an active error flag. The active error flag is however, can only be generated during an interframe
composed of six consecutive dominant bits. This bit space. In this way, an overload frame can be
sequence actively violates the bit-stuffing rule. All other differentiated from an error frame (an error frame is
stations recognize the resulting bit-stuffing error and, in sent during the transmission of a message). The
turn, generate error frames themselves, called error overload frame consists of two fields: an overload flag
echo flags. followed by an overload delimiter. The overload flag
The error flag field, therefore, consists of between six consists of six dominant bits followed by overload flags
and twelve consecutive dominant bits (generated by generated by other nodes (and, as for an active error
one or more nodes). The error delimiter field (eight flag, giving a maximum of twelve dominant bits). The
recessive bits) completes the error frame. Upon overload delimiter consists of eight recessive bits. An
completion of the error frame, bus activity returns to overload frame can be generated by a node as a result
normal and the interrupted node attempts to resend the of two conditions:
aborted message. 1. The node detects a dominant bit during the
interframe space, an illegal condition.
Note: Error echo flags typically occur when a Exception: The dominant bit is detected during
localized disturbance causes one or more the third bit of IFS. In this case, the receivers will
(but not all) nodes to send an error flag. interpret this as a SOF.
The remaining nodes generate error flags
2. Due to internal conditions, the node is not yet
in response (echo) to the original error
able to begin reception of the next message. A
flag.
node may generate a maximum of two
2.4.2 PASSIVE ERRORS sequential overload frames to delay the start of
the next message.
If an error-passive node detects a bus error, the node
transmits an error-passive flag followed by the error Note: Case 2 should never occur with the
delimiter field. The error-passive flag consists of six MCP2515 due to very short internal
consecutive recessive bits. The error frame for an error- delays.
passive node consists of 14 recessive bits. From this, it
follows that unless the bus error is detected by an error- 2.6 Interframe Space
active node or the transmitting node, the message will
continue transmission because the error-passive flag The interframe space separates a preceding frame (of
does not interfere with the bus. any type) from a subsequent data or remote frame.
The interframe space is composed of at least three
If the transmitting node generates an error-passive flag,
recessive bits called the Intermission. This allows
it will cause other nodes to generate error frames due to
nodes time for internal processing before the start of
the resulting bit-stuffing violation. After transmission of
the next message frame. After the intermission, the
an error frame, an error-passive node must wait for six
bus line remains in the recessive state (bus idle) until
consecutive recessive bits on the bus before attempting
the next transmission starts.
to rejoin bus communications.
The error delimiter consists of eight recessive bits, and
allows the bus nodes to restart bus communications
cleanly after an error has occurred.

DS21801G-page 8  2003-2012 Microchip Technology Inc.

 FIGURE 2-1:

 2003-2012 Microchip Technology Inc.

Data Frame (number of bits = 44 + 8N)

12 6 8N (0N8) 16 7
Arbitration Field Control Data Field CRC Field
Field End-of-
4 Frame
STANDARD DATA FRAME

11 8 8 15
CRC

Start-of-Frame
IFS
ACK Del
Ack Slot Bit
CRC Del

DLC3

ID 10
ID3
ID0
DLC0

IDE
RB0

RTR
0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1

Identifier Data
Length
Message Code
Filtering

Reserved Bit
Stored in Transmit/Receive Buffers
Stored in Buffers
Bit-stuffing

DS21801G-page 9
MCP2515
 FIGURE 2-2:

DS21801G-page 10
MCP2515

Data Frame (number of bits = 64 + 8N)

32 6 8N (0 N 8) 16 7
Arbitration Field Control Data Field CRC Field
Field End-of-
11 18 8 8 15 Frame
4
CRC
EXTENDED DATA FRAME

IFS
ACK Del
Ack Slot Bit

ID10
ID3
SRR
IDE
EID17
EID0
RTR
RB1
RB0
DLC3
DLC0

ID0
CRC Del

Start-Of-Frame
0 11 000 1 11111111111

Identifier Data
Extended Identifier
Length
Message Code
Filtering

Reserved bits
Stored in Buffers Stored in Transmit/Receive Buffers

Bit-stuffing

 2003-2012 Microchip Technology Inc.

 FIGURE 2-3:

 2003-2012 Microchip Technology Inc.

32 6 16 7
REMOTE FRAME

Arbitration Field Control CRC Field

Field End-of-
11 18 15 Frame
4
CRC
IFS
ACK Del
Ack Slot Bit

ID10
ID3
SRR
IDE
EID17
EID0
RTR
RB1
RB0
DLC3
DLC0
CRC Del

ID0

Start-Of-Frame
0 11 100 1 11111111111

Identifier Data
Extended Identifier
Length
Message Code
Filtering Reserved bits

Remote Frame with Extended Identifier

No data field

DS21801G-page 11
MCP2515
 FIGURE 2-4:

DS21801G-page 12
MCP2515

Interrupted Data Frame

12 6 8N (0N8)
Arbitration Field Control Data Field
Field
4
11 8 8

Start-Of-Frame
DLC3

ID 10
ID3
ID0
DLC0

IDE
RB0

RTR
ACTIVE ERROR FRAME

0 0 0 0

Identifier Data
Length
Message Code
Filtering

Reserved Bit
Error Frame

Bit-stuffing 8
6 £6
Data Frame or
Error Echo Error Inter-Frame Space or
Remote Frame
Flag Error Delimiter Overload Frame
Flag

0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0

 2003-2012 Microchip Technology Inc.

 FIGURE 2-5:

Remote Frame (number of bits = 44)

 2003-2012 Microchip Technology Inc.

12 6 16 7
Arbitration Field Control CRC Field
Field End-of-
OVERLOAD FRAME

4 Frame
11 15
CRC

Start-Of-Frame
ACK Del
Ack Slot Bit
CRC Del

DLC3

ID 10
ID0
IDE
DLC0

RB0

RTR
0 1 0 0 1 1 1 1 1 1 1 1 1

Overload Frame
End-of-Frame or Inter-Frame Space or
Error Delimiter or 6 8 Error Frame
Overload Delimiter
Overload Overload
Flag Delimiter

0 0 0 0 0 0 0 1 1 1 1 1 1 1 1

DS21801G-page 13
MCP2515
MCP2515
NOTES:

DS21801G-page 14  2003-2012 Microchip Technology Inc.

 MCP2515
3.0 MESSAGE TRANSMISSION 3.3 Initiating Transmission
In order to initiate message transmission, the
3.1 Transmit Buffers TXBnCTRL.TXREQ bit must be set for each buffer to
The MCP2515 implements three transmit buffers. Each be transmitted. This can be accomplished by:
of these buffers occupies 14 bytes of SRAM and are • Writing to the register via the SPI write command
mapped into the device memory map. • Sending the SPI RTS command
The first byte, TXBnCTRL, is a control register • Setting the TXnRTS pin low for the particular
associated with the message buffer. The information in transmit buffer(s) that are to be transmitted
this register determines the conditions under which the If transmission is initiated via the SPI interface, the
message will be transmitted and indicates the status of TXREQ bit can be set at the same time as the TXP
the message transmission (see Register 3-2). priority bits.
Five bytes are used to hold the standard and extended When TXBnCTRL.TXREQ is set, the TXBnCTRL.ABTF,
identifiers, as well as other message arbitration TXBnCTRL.MLOA and TXBnCTRL.TXERR bits will be
information (see Register 3-4 through Register 3-7). cleared automatically.
The last eight bytes are for the eight possible data
bytes of the message to be transmitted (see Note: Setting the TXBnCTRL.TXREQ bit does
Register 3-8). not initiate a message transmission. It
At a minimum, the TXBnSIDH, TXBnSIDL and merely flags a message buffer as being
TXBnDLC registers must be loaded. If data bytes are ready for transmission. Transmission will
present in the message, the TXBnDm registers must start when the device detects that the bus
also be loaded. If the message is to use extended is available.
identifiers, the TXBnEIDm registers must also be Once the transmission has completed successfully, the
loaded and the TXBnSIDL.EXIDE bit set. TXBnCTRL.TXREQ bit will be cleared, the
Prior to sending the message, the MCU must initialize CANINTF.TXnIF bit will be set and an interrupt will be
the CANINTE.TXInE bit to enable or disable the generated if the CANINTE.TXnIE bit is set.
generation of an interrupt when the message is sent. If the message transmission fails, the
TXBnCTRL.TXREQ will remain set. This indicates that
Note: The TXBnCTRL.TXREQ bit must be clear the message is still pending for transmission and one
(indicating the transmit buffer is not of the following condition flags will be set:
pending transmission) before writing to
the transmit buffer. • If the message started to transmit but encoun-
tered an error condition, the TXBnCTRL.TXERR
and the CANINTF.MERRF bits will be set and an
3.2 Transmit Priority
interrupt will be generated on the INT pin if the
Transmit priority is a prioritization within the MCP2515 CANINTE.MERRE bit is set
of the pending transmittable messages. This is • If the message is lost, arbitration at the
independent from, and not necessarily related to, any TXBnCTRL.MLOA bit will be set
prioritization implicit in the message arbitration scheme
built into the CAN protocol. Note: If One-Shot mode is enabled
(CANCTRL.OSM), the above conditions
Prior to sending the SOF, the priority of all buffers that
will still exist. However, the TXREQ bit will
are queued for transmission is compared. The transmit
be cleared and the message will not
buffer with the highest priority will be sent first. For
attempt transmission a second time.
example, if transmit buffer 0 has a higher priority setting
than transmit buffer 1, buffer 0 will be sent first.
3.4 One-Shot Mode
If two buffers have the same priority setting, the buffer
with the highest buffer number will be sent first. For One-Shot mode ensures that a message will only
example, if transmit buffer 1 has the same priority attempt to transmit one time. Normally, if a CAN
setting as transmit buffer 0, buffer 1 will be sent first. message loses arbitration, or is destroyed by an error
frame, the message is retransmitted. With One-Shot
There are four levels of transmit priority. If
mode enabled, a message will only attempt to transmit
TXBnCTRL.TXP<1:0> for a particular message buffer
one time, regardless of arbitration loss or error frame.
is set to 11, that buffer has the highest possible priority.
If TXBnCTRL.TXP<1:0> for a particular message buf- One-Shot mode is required to maintain time slots in
fer is 00, that buffer has the lowest possible priority. deterministic systems, such as TTCAN.

 2003-2012 Microchip Technology Inc. DS21801G-page 15

MCP2515
3.5 TXnRTS PINS 3.6 Aborting Transmission
The TXnRTS pins are input pins that can be configured The MCU can request to abort a message in a specific
as: message buffer by clearing the associated
• Request-to-send inputs, which provide an TXBnCTRL.TXREQ bit.
alternative means of initiating the transmission of In addition, all pending messages can be requested to
a message from any of the transmit buffers be aborted by setting the CANCTRL.ABAT bit. This bit
• Standard digital inputs MUST be reset (typically after the TXREQ bits have
been verified to be cleared) to continue transmitting
Configuration and control of these pins is accomplished
messages. The TXBnCTRL.ABTF flag will only be set
using the TXRTSCTRL register (see Register 3-3). The
if the abort was requested via the CANCTRL.ABAT bit.
TXRTSCTRL register can only be modified when the
Aborting a message by resetting the TXREQ bit does
MCP2515 is in Configuration mode (see Section 10.0
NOT cause the ABTF bit to be set.
“Modes of Operation”). If configured to operate as a
request-to-send pin, the pin is mapped into the Note 1: Messages that were transmitting when
respective TXBnCTRL.TXREQ bit for the transmit the abort was requested will continue to
buffer. The TXREQ bit is latched by the falling edge of transmit. If the message does not
the TXnRTS pin. The TXnRTS pins are designed to successfully complete transmission (i.e.,
allow them to be tied directly to the RXnBF pins to lost arbitration or was interrupted by an
automatically initiate a message transmission when the error frame), it will then be aborted.
RXnBF pin goes low.
2: When One-Shot mode is enabled, if the
The TXnRTS pins have internal pull-up resistors of message is interrupted due to an error
100 k (nominal). frame or loss of arbitration, the
TXBnCTRL.ABTF bit will set.

DS21801G-page 16  2003-2012 Microchip Technology Inc.

 MCP2515
FIGURE 3-1: TRANSMIT MESSAGE FLOWCHART

Start
The message transmission
sequence begins when the
device determines that the
TXBnCTRL.TXREQ for any of
the transmit registers has been
set.
No Are any
TXBnCTRL.TXREQ
bits = 1
?

Yes

Clearing the TxBnCTRL.TXREQ bit

Clear: while it is set, or setting the CANC-
TXBnCTRL.ABTF TRL.ABAT bit before the message
TXBnCTRL.MLOA has started transmission, will abort
TXBnCTRL.TXERR the message.

Is is
CAN bus available No TXBnCTRL.TXREQ=0 No
to start transmission? or CANCTRL.ABAT=1
?

Yes Yes

Examine TXBnCTRL.TXP <1:0> to

Determine Highest Priority Message

Transmit Message

Message
Was No Message error
Error
Message Transmitted or
Successfully? Lost arbitration
? Set
TxBnCTRL.TXERR
Yes Lost
Clear TxBnCTRL.TXREQ Arbitration

Yes
CANINTE.MEERE?
Yes
Generate Set
CANINTE.TXnIE=1? TxBNCTRL.MLOA
Interrupt
No
Generate
Interrupt
No

Set Set
CANTINF.TXnIF CANTINF.MERRF
The CANINTE.TXnIE bit
determines if an interrupt
should be generated when
a message is successfully
transmitted.

GOTO START

 2003-2012 Microchip Technology Inc. DS21801G-page 17

MCP2515
REGISTER 3-1: TXBnCTRL – TRANSMIT BUFFER n CONTROL REGISTER
(ADDRESS: 30h, 40h, 50h)
U-0 R-0 R-0 R-0 R/W-0 U-0 R/W-0 R/W-0
— ABTF MLOA TXERR TXREQ — TXP1 TXP0
bit 7 bit 0

Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 7 Unimplemented: Read as ‘0’

bit 6 ABTF: Message Aborted Flag bit
1 = Message was aborted
0 = Message completed transmission successfully
bit 5 MLOA: Message Lost Arbitration bit
1 = Message lost arbitration while being sent
0 = Message did not lose arbitration while being sent
bit 4 TXERR: Transmission Error Detected bit
1 = A bus error occurred while the message was being transmitted
0 = No bus error occurred while the message was being transmitted
bit 3 TXREQ: Message Transmit Request bit
1 = Buffer is currently pending transmission
(MCU sets this bit to request message be transmitted - bit is automatically cleared when
the message is sent)
0 = Buffer is not currently pending transmission
(MCU can clear this bit to request a message abort)
bit 2 Unimplemented: Read as ‘0’
bit 1-0 TXP<1:0>: Transmit Buffer Priority bits
11 = Highest Message Priority
10 = High Intermediate Message Priority
01 = Low Intermediate Message Priority
00 = Lowest Message Priority

DS21801G-page 18  2003-2012 Microchip Technology Inc.

 MCP2515
REGISTER 3-2: TXRTSCTRL – TXnRTS PIN CONTROL AND STATUS REGISTER
(ADDRESS: 0Dh)
U-0 U-0 R-x R-x R-x R/W-0 R/W-0 R/W-0
— — B2RTS B1RTS B0RTS B2RTSM B1RTSM B0RTSM
bit 7 bit 0

Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 7-6 Unimplemented: Read as ‘0’

bit 5 B2RTS: TX2RTS Pin State bit
- Reads state of TX2RTS pin when in Digital Input mode
- Reads as ‘0’ when pin is in ‘Request-to-Send’ mode
bit 4 B1RTS: TX1RTX Pin State bit
- Reads state of TX1RTS pin when in Digital Input mode
- Reads as ‘0’ when pin is in ‘Request-to-Send’ mode
bit 3 B0RTS: TX0RTS Pin State bit
- Reads state of TX0RTS pin when in Digital Input mode
- Reads as ‘0’ when pin is in ‘Request-to-Send’ mode
bit 2 B2RTSM: TX2RTS Pin mode bit
1 = Pin is used to request message transmission of TXB2 buffer (on falling edge)
0 = Digital input
bit 1 B1RTSM: TX1RTS Pin mode bit
1 = Pin is used to request message transmission of TXB1 buffer (on falling edge)
0 = Digital input
bit 0 B0RTSM: TX0RTS Pin mode bit
1 = Pin is used to request message transmission of TXB0 buffer (on falling edge)
0 = Digital input

REGISTER 3-3: TXBnSIDH – TRANSMIT BUFFER n STANDARD IDENTIFIER HIGH

(ADDRESS: 31h, 41h, 51h)
R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x
SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3
bit 7 bit 0

Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 7-0 SID<10:3>: Standard Identifier bits

 2003-2012 Microchip Technology Inc. DS21801G-page 19

MCP2515
REGISTER 3-4: TXBnSIDL – TRANSMIT BUFFER n STANDARD IDENTIFIER LOW
(ADDRESS: 32h, 42h, 52h)
R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x
SID2 SID1 SID0 — EXIDE — EID17 EID16
bit 7 bit 0

Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 7-5 SID<2:0>: Standard Identifier bits

bit 4 Unimplemented: Reads as ‘0’
bit 3 EXIDE: Extended Identifier Enable bit
1 = Message will transmit extended identifier
0 = Message will transmit standard identifier
bit 2 Unimplemented: Reads as ‘0’
bit 1-0 EID<17:16>: Extended Identifier bits

REGISTER 3-5: TXBnEID8 – TRANSMIT BUFFER n EXTENDED IDENTIFIER HIGH

(ADDRESS: 33h, 43h, 53h)
R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x
EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8
bit 7 bit 0

Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 7-0 EID<15:8>: Extended Identifier bits

REGISTER 3-6: TXBnEID0 – TRANSMIT BUFFER n EXTENDED IDENTIFIER LOW

(ADDRESS: 34h, 44h, 54h)
R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x
EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0
bit 7 bit 0

Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 7-0 EID<7:0>: Extended Identifier bits

DS21801G-page 20  2003-2012 Microchip Technology Inc.

 MCP2515
REGISTER 3-7: TXBnDLC - TRANSMIT BUFFER n DATA LENGTH CODE
(ADDRESS: 35h, 45h, 55h)
R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x
— RTR — — DLC3 DLC2 DLC1 DLC0
bit 7 bit 0

Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 7 Unimplemented: Reads as ‘0’

bit 6 RTR: Remote Transmission Request bit
1 = Transmitted Message will be a Remote Transmit Request
0 = Transmitted Message will be a Data Frame
bit 5-4 Unimplemented: Reads as ‘0’
bit 3-0 DLC<3:0>: Data Length Code bits
Sets the number of data bytes to be transmitted (0 to 8 bytes)
Note: It is possible to set the DLC to a value greater than eight, however only eight bytes are
transmitted

REGISTER 3-8: TXBnDm – TRANSMIT BUFFER n DATA BYTE m

(ADDRESS: 36h - 3Dh, 46h - 4Dh, 56h - 5Dh)
R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x
TXBnDm7 TXBnDm6 TXBnDm5 TXBnDm4 TXBnDm3 TXBnDm2 TXBnDm1 TXBnDm0
bit 7 bit 0

Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 7-0 TXBnDm7:TXBnDm0: Transmit Buffer n Data Field Bytes m

 2003-2012 Microchip Technology Inc. DS21801G-page 21

MCP2515
NOTES:

DS21801G-page 22  2003-2012 Microchip Technology Inc.

 MCP2515
4.0 MESSAGE RECEPTION 4.2 Receive Priority
RXB0, the higher priority buffer, has one mask and two
4.1 Receive Message Buffering message acceptance filters associated with it. The
The MCP2515 includes two full receive buffers with received message is applied to the mask and filters for
multiple acceptance filters for each. There is also a RXB0 first.
separate Message Assembly Buffer (MAB) that acts as RXB1 is the lower priority buffer, with one mask and
a third receive buffer (see Figure 4-2). four acceptance filters associated with it.
In addition to the message being applied to the RB0
4.1.1 MESSAGE ASSEMBLY BUFFER
mask and filters first, the lower number of acceptance
Of the three receive buffers, the MAB is always filters makes the match on RXB0 more restrictive and
committed to receiving the next message from the bus. implies a higher priority for that buffer.
The MAB assembles all messages received. These
When a message is received, bits <3:0> of the
messages will be transferred to the RXBn buffers (see
RXBnCTRL register will indicate the acceptance filter
Register 4-4 to Register 4-9) only if the acceptance
number that enabled reception and whether the
filter criteria is met.
received message is a remote transfer request.
4.1.2 RXB0 AND RXB1 4.2.1 ROLLOVER
The remaining two receive buffers, called RXB0 and
Additionally, the RXB0CTRL register can be configured
RXB1, can receive a complete message from the
such that, if RXB0 contains a valid message and
protocol engine via the MAB. The MCU can access one
another valid message is received, an overflow error
buffer, while the other buffer is available for message
will not occur and the new message will be moved into
reception, or for holding a previously received
RXB1, regardless of the acceptance criteria of RXB1.
message.
4.2.2 RXM BITS
Note: The entire content of the MAB is moved
into the receive buffer once a message is The RXBnCTRL.RXM bits set special receive modes.
accepted. This means, that regardless of Normally, these bits are cleared to 00 to enable
the type of identifier (standard or reception of all valid messages as determined by the
extended) and the number of data bytes appropriate acceptance filters. In this case, the
received, the entire receive buffer is determination of whether or not to receive standard or
overwritten with the MAB contents. extended messages is determined by the
Therefore, the contents of all registers in RFXnSIDL.EXIDE bit in the acceptance filter register.
the buffer must be assumed to have been If the RXBnCTRL.RXM bits are set to 01 or 10, the
modified when any message is received. receiver will only accept messages with standard or
extended identifiers, respectively. If an acceptance
4.1.3 RECEIVE FLAGS/INTERRUPTS filter has the RFXnSIDL.EXIDE bit set such that it does
When a message is moved into either of the receive not correspond with the RXBnCTRL.RXM mode, that
buffers, the appropriate CANINTF.RXnIF bit is set. This acceptance filter is rendered useless. These two
bit must be cleared by the MCU in order to allow a new modes of RXBnCTRL.RXM bits can be used in
message to be received into the buffer. This bit systems where it is known that only standard or
provides a positive lockout to ensure that the MCU has extended messages will be on the bus.
finished with the message before the MCP2515 If the RXBnCTRL.RXM bits are set to 11, the buffer will
attempts to load a new message into the receive buffer. receive all messages, regardless of the values of the
If the CANINTE.RXnIE bit is set, an interrupt will be acceptance filters. Also, if a message has an error
generated on the INT pin to indicate that a valid before the EOF, that portion of the message assembled
message has been received. In addition, the in the MAB before the error frame will be loaded into the
associated RXnBF pin will drive low if configured as a buffer. This mode has some value in debugging a CAN
receive buffer full pin. See Section 4.4 “RX0BF and system and would not be used in an actual system
RX1BF Pins” for details. environment.

 2003-2012 Microchip Technology Inc. DS21801G-page 23

MCP2515
4.3 Start-of-Frame Signal 4.4.1 DISABLED
If enabled, the Start-Of-Frame signal is generated on The RXBnBF pins can be disabled to the high-
the SOF pin at the beginning of each CAN message impedance state by clearing BFPCTRL.BnBFE.
detected on the RXCAN pin.
4.4.2 CONFIGURED AS BUFFER FULL
The RXCAN pin monitors an idle bus for a recessive-
to-dominant edge. If the dominant condition remains The RXBnBF pins can be configured to act as either
until the sample point, the MCP2515 interprets this as buffer full interrupt pins or as standard digital outputs.
a SOF and a SOF pulse is generated. If the dominant Configuration and status of these pins is available via
condition does not remain until the sample point, the the BFPCTRL register (Register 4-3). When set to
MCP2515 interprets this as a glitch on the bus and no operate in Interrupt mode (by setting BFPCTRL.BxBFE
SOF signal is generated. Figure 4-1 illustrates SOF and BFPCTRL.BxBFM bits), these pins are active-low
signalling and glitch-filtering. and are mapped to the CANINTF.RXnIF bit for each
receive buffer. When this bit goes high for one of the
As with One-Shot mode, one use for SOF signaling is receive buffers (indicating that a valid message has
for TTCAN-type systems. In addition, by monitoring been loaded into the buffer), the corresponding
both the RXCAN pin and the SOF pin, an MCU can RXBnBF pin will go low. When the CANINTF.RXnIF bit
detect early physical bus problems by detecting small is cleared by the MCU, the corresponding interrupt pin
glitches before they affect the CAN communications. will go to the logic-high state until the next message is
loaded into the receive buffer.
4.4 RX0BF and RX1BF Pins
In addition to the INT pin, which provides an interrupt
signal to the MCU for many different conditions, the
receive buffer full pins (RX0BF and RX1BF) can be
used to indicate that a valid message has been loaded
into RXB0 or RXB1, respectively. The pins have three
different configurations (Register 4-1):
1. Disabled
2. Buffer Full Interrupt
3. Digital Output

FIGURE 4-1: START-OF-FRAME SIGNALING

Normal SOF Signaling

START-OF-FRAME BIT ID BIT

Sample
Point
RXCAN

SOF

Glitch-Filtering
EXPECTED START-OF-FRAME BIT

Expected Sample
Point BUS IDLE

RXCAN

SOF

DS21801G-page 24  2003-2012 Microchip Technology Inc.

 MCP2515
4.4.3 CONFIGURED AS DIGITAL OUTPUT TABLE 4-1: CONFIGURING RXNBF PINS
When used as digital outputs, the BFPCTRL.BxBFM bit BnBFE BnBFM BnBFS Pin Status
must be cleared and BFPCTRL.BnBFE must be set for
0 X X Disabled, high-impedance
the associated buffer. In this mode, the state of the pin
is controlled by the BFPCTRL.BnBFS bits. Writing a ‘1’ 1 1 X Receive buffer interrupt
to the BnBFS bit will cause a high level to be driven on 1 0 0 Digital output = 0
the associated buffer full pin, while a ‘0’ will cause the 1 0 1 Digital output = 1
pin to drive low. When using the pins in this mode, the
state of the pin should be modified only by using the Bit
Modify SPI command to prevent glitches from
occurring on either of the buffer full pins.

FIGURE 4-2: RECEIVE BUFFER BLOCK DIAGRAM

Note: Messages received in the MAB are intially

applied to the mask and filters of RXB0. In
addition, only one filter match occurs (e.g.,
Acceptance Mask
if the message matches both RXF0 and
RXM1
RXF2, the match will be for RXF0 and the
message will be moved into RXB0).
Acceptance Filter
RXF2

Acceptance Mask Acceptance Filter

RXM0 RXF3
A
c
Acceptance Filter Acceptance Filter c
RXF0 RXF4 e
A p
c t
c Acceptance Filter Acceptance Filter
e RXF1 RXF5
p
t

R R
Identifier M Identifier
X X
A
B B
B
0 1

Data Field Data Field

 2003-2012 Microchip Technology Inc. DS21801G-page 25

MCP2515
FIGURE 4-3: RECEIVE FLOW FLOWCHART

Start

Detect
No
Start of
Message?

Yes

Begin Loading Message into

Message Assembly Buffer (MAB)

Valid
Generate No
Error Message
Frame Received?

Yes

Meets Meets
Yes No Yes
a filter criteria a filter criteria
for RXB0? for RXB1?

No

Go to Start
Determines if the receive
register is empty and able
to accept a new message

Determines if RXB0 can roll

over into RXB1, if it is full.

Is No Is Yes
CANINTF.RX0IF = 0? RXB0CTRL.BUKT = 1?

Yes No
No Is
Move message into RXB0 Generate Overflow Error: Generate Overflow Error: CANINTF.RX1IF = 0?
Set EFLG.RX0OVR Set EFLG.RX1OVR

Set CANINTF.RX0IF = 1 Yes

No Move message into RXB1

Is
Set RXB0CTRL.FILHIT <0>
CANINTE.ERRIE = 1?
according to which filter criteria
Set CANINTF.RX1IF = 1
Yes
Set RXB0CTRL.FILHIT <2:0>
Generate according to which filter criteria
Go to Start
Interrupt on INT was met

Yes Generate Yes

CANINTE.RX0IE = 1? CANINTE.RX1IE = 1?
Interrupt on INT

RXB0 RXB1
No Set CANSTAT <3:0> accord- No
ing to which receive buffer
the message was loaded into
Are Are
BFPCTRL.B0BFM = 1 Yes Yes BFPCTRL.B1BFM = 1
Set RXBF0 Set RXBF1
and and
Pin = 0 Pin = 0
BF1CTRL.B0BFE = 1? BF1CTRL.B1BFE = 1?

No No

DS21801G-page 26  2003-2012 Microchip Technology Inc.

 MCP2515
REGISTER 4-1: RXB0CTRL – RECEIVE BUFFER 0 CONTROL
(ADDRESS: 60h)
U-0 R/W-0 R/W-0 U-0 R-0 R/W-0 R-0 R-0
— RXM1 RXM0 — RXRTR BUKT BUKT1 FILHIT0
bit 7 bit 0

Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 7 Unimplemented: Read as ‘0’

bit 6-5 RXM<1:0>: Receive Buffer Operating mode bits
11 = Turn mask/filters off; receive any message
10 = Receive only valid messages with extended identifiers that meet filter criteria
01 = Receive only valid messages with standard identifiers that meet filter criteria. Extended ID filter
registers RXFnEID8:RXFnEID0 are ignored for the messages with standard IDs.
00 = Receive all valid messages using either standard or extended identifiers that meet filter criteria.
Extended ID filter registers RXFnEID8:RXFnEID0 are applied to first two bytes of data in the
messages with standard IDs.
bit 4 Unimplemented: Read as ‘0’
bit 3 RXRTR: Received Remote Transfer Request bit
1 = Remote Transfer Request Received
0 = No Remote Transfer Request Received
bit 2 BUKT: Rollover Enable bit
1 = RXB0 message will rollover and be written to RXB1 if RXB0 is full
0 = Rollover disabled
bit 1 BUKT1: Read-only Copy of BUKT bit (used internally by the MCP2515)
bit 0 FILHIT0: Filter Hit bit – indicates which acceptance filter enabled reception of message
1 = Acceptance Filter 1 (RXF1)
0 = Acceptance Filter 0 (RXF0)
Note: If a rollover from RXB0 to RXB1 occurs, the FILHIT bit will reflect the filter that accepted
the message that rolled over.

 2003-2012 Microchip Technology Inc. DS21801G-page 27

MCP2515
REGISTER 4-2: RXB1CTRL – RECEIVE BUFFER 1 CONTROL
(ADDRESS: 70h)
U-0 R/W-0 R/W-0 U-0 R-0 R-0 R-0 R-0
— RXM1 RXM0 — RXRTR FILHIT2 FILHIT1 FILHIT0
bit 7 bit 0

Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 7 Unimplemented: Read as ‘0’

bit 6-5 RXM<1:0>: Receive Buffer Operating mode bits
11 = Turn mask/filters off; receive any message
10 = Receive only valid messages with extended identifiers that meet filter criteria
01 = Receive only valid messages with standard identifiers that meet filter criteria
00 = Receive all valid messages using either standard or extended identifiers that meet filter criteria
bit 4 Unimplemented: Read as ‘0’
bit 3 RXRTR: Received Remote Transfer Request bit
1 = Remote Transfer Request Received
0 = No Remote Transfer Request Received
bit 2-0 FILHIT<2:0>: Filter Hit bits - indicates which acceptance filter enabled reception of message
101 = Acceptance Filter 5 (RXF5)
100 = Acceptance Filter 4 (RXF4)
011 = Acceptance Filter 3 (RXF3)
010 = Acceptance Filter 2 (RXF2)
001 = Acceptance Filter 1 (RXF1) (Only if BUKT bit set in RXB0CTRL)
000 = Acceptance Filter 0 (RXF0) (Only if BUKT bit set in RXB0CTRL)

DS21801G-page 28  2003-2012 Microchip Technology Inc.

 MCP2515
REGISTER 4-3: BFPCTRL – RXnBF PIN CONTROL AND STATUS
(ADDRESS: 0Ch)
U-0 U-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0
— — B1BFS B0BFS B1BFE B0BFE B1BFM B0BFM
bit 7 bit 0

Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 7-6 Unimplemented: Read as ‘0’

bit 5 B1BFS: RX1BF Pin State bit (Digital Output mode only)
- Reads as ‘0’ when RX1BF is configured as interrupt pin
bit 4 B0BFS: RX0BF Pin State bit (Digital Output mode only)
- Reads as ‘0’ when RX0BF is configured as interrupt pin
bit 3 B1BFE: RX1BF Pin Function Enable bit
1 = Pin function enabled, operation mode determined by B1BFM bit
0 = Pin function disabled, pin goes to high-impedance state
bit 2 B0BFE: RX0BF Pin Function Enable bit
1 = Pin function enabled, operation mode determined by B0BFM bit
0 = Pin function disabled, pin goes to high-impedance state
bit 1 B1BFM: RX1BF Pin Operation mode bit
1 = Pin is used as interrupt when valid message loaded into RXB1
0 = Digital Output mode
bit 0 B0BFM: RX0BF Pin Operation mode bit
1 = Pin is used as interrupt when valid message loaded into RXB0
0 = Digital Output mode

REGISTER 4-4: RXBnSIDH – RECEIVE BUFFER n STANDARD IDENTIFIER HIGH

(ADDRESS: 61h, 71h)
R-x R-x R-x R-x R-x R-x R-x R-x
SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3
bit 7 bit 0

Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 7-0 SID<10:3>: Standard Identifier bits

These bits contain the eight Most Significant bits of the Standard Identifier for the received message

 2003-2012 Microchip Technology Inc. DS21801G-page 29

MCP2515
REGISTER 4-5: RXBnSIDL – RECEIVE BUFFER n STANDARD IDENTIFIER LOW
(ADDRESS: 62h, 72h)
R-x R-x R-x R-x R-x U-0 R-x R-x
SID2 SID1 SID0 SRR IDE — EID17 EID16
bit 7 bit 0

Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 7-5 SID<2:0>: Standard Identifier bits

These bits contain the three Least Significant bits of the Standard Identifier for the received message
bit 4 SRR: Standard Frame Remote Transmit Request bit (valid only if IDE bit = ‘0’)
1 = Standard Frame Remote Transmit Request Received
0 = Standard Data Frame Received
bit 3 IDE: Extended Identifier Flag bit
This bit indicates whether the received message was a Standard or an Extended Frame
1 = Received message was an Extended Frame
0 = Received message was a Standard Frame
bit 2 Unimplemented: Reads as ‘0’
bit 1-0 EID<17:16>: Extended Identifier bits
These bits contain the two Most Significant bits of the Extended Identifier for the received message

REGISTER 4-6: RXBnEID8 – RECEIVE BUFFER n EXTENDED IDENTIFIER HIGH

(ADDRESS: 63h, 73h)
R-x R-x R-x R-x R-x R-x R-x R-x
EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8
bit 7 bit 0

Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 7-0 EID<15:8>: Extended Identifier bits

These bits hold bits 15 through 8 of the Extended Identifier for the received message

DS21801G-page 30  2003-2012 Microchip Technology Inc.

 MCP2515
REGISTER 4-7: RXBnEID0 – RECEIVE BUFFER n EXTENDED IDENTIFIER LOW
(ADDRESS: 64h, 74h)
R-x R-x R-x R-x R-x R-x R-x R-x
EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0
bit 7 bit 0

Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 7-0 EID<7:0>: Extended Identifier bits

These bits hold the Least Significant eight bits of the Extended Identifier for the received message

REGISTER 4-8: RXBnDLC – RECEIVE BUFFER n DATA LENGTH CODE

(ADDRESS: 65h, 75h)
R-x R-x R-x R-x R-x R-x R-x R-x
— RTR RB1 RB0 DLC3 DLC2 DLC1 DLC0
bit 7 bit 0

Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 7 Unimplemented: Reads as ‘0’

bit 6 RTR: Extended Frame Remote Transmission Request bit
(valid only when RXBnSIDL.IDE = 1)
1 = Extended Frame Remote Transmit Request Received
0 = Extended Data Frame Received
bit 5 RB1: Reserved Bit 1
bit 4 RB0: Reserved Bit 0
bit 3-0 DLC<3:0>: Data Length Code bits
Indicates number of data bytes that were received

REGISTER 4-9: RXBnDM – RECEIVE BUFFER n DATA BYTE M

(ADDRESS: 66h - 6Dh, 76h - 7Dh)
R-x R-x R-x R-x R-x R-x R-x R-x
RBnD7 RBnD6 RBnD5 RBnD4 RBnD3 RBnD2 RBnD1 RBnD0
bit 7 bit 0

Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 7-0 RBnD7:RBnD0: Receive Buffer n Data Field Bytes m

Eight bytes containing the data bytes for the received message

 2003-2012 Microchip Technology Inc. DS21801G-page 31

MCP2515
4.5 Message Acceptance Filters and identifier is compared to the masks and filters to deter-
Masks mine if the message should be loaded into a receive
buffer. The mask essentially determines which bits to
The message acceptance filters and masks are used to apply the acceptance filters to. If any mask bit is set to
determine if a message in the message assembly buf- a zero, that bit will automatically be accepted,
fer should be loaded into either of the receive buffers regardless of the filter bit.
(see Figure 4-5). Once a valid message has been
received into the MAB, the identifier fields of the mes- TABLE 4-2: FILTER/MASK TRUTH TABLE
sage are compared to the filter values. If there is a
Message
match, that message will be loaded into the appropriate Accept or
Mask Bit n Filter Bit n Identifier
receive buffer. Reject bit n
bit
4.5.1 DATA BYTE FILTERING 0 X X Accept
When receiving standard data frames (11-bit identifier), 1 0 0 Accept
the MCP2515 automatically applies 16 bits of masks 1 0 1 Reject
and filters normally associated with extended 1 1 0 Reject
identifiers to the first 16 bits of the data field (data bytes
1 1 1 Accept
0 and 1). Figure 4-4 illustrates how masks and filters
apply to extended and standard data frames. Note: X = don’t care
Data byte filtering reduces the load on the MCU when As shown in the receive buffers block diagram
implementing Higher Layer Protocols (HLPs) that filter (Figure 4-2), acceptance filters RXF0 and RXF1 (and
on the first data byte (e.g., DeviceNet™). filter mask RXM0) are associated with RXB0. Filters
RXF2, RXF3, RXF4, RXF5 and mask RXM1 are
4.5.2 FILTER MATCHING associated with RXB1.
The filter masks (see Register 4-14 through
Register 4-17) are used to determine which bits in the
identifier are examined with the filters. A truth table is
shown in Table 4-2 that indicates how each bit in the

FIGURE 4-4: MASKS AND FILTERS APPLY TO CAN FRAMES

Extended Frame

ID10 ID0 EID17 EID0

Masks and Filters apply to the entire 29-bit ID field

Standard Data Frame

ID10 ID0 * Data Byte 0 Data Byte 1

11-bit ID Standard frame 16-bit data filtering *

* The two MSb (EID17 and EID16) mask and filter bits are not used.

DS21801G-page 32  2003-2012 Microchip Technology Inc.

 MCP2515
4.5.3 FILHIT BITS If the BUKT bit is clear, there are six codes
corresponding to the six filters. If the BUKT bit is set,
Filter matches on received messages can be
there are six codes corresponding to the six filters, plus
determined by the FILHIT bits in the associated
two additional codes corresponding to RXF0 and RXF1
RXBnCTRL register. RXB0CTRL.FILHIT0 for buffer 0
filters that roll over into RXB1.
and RXB1CTRL.FILHIT<2:0> for buffer 1.
The three FILHIT bits for receive buffer 1 (RXB1) are 4.5.4 MULTIPLE FILTER MATCHES
coded as follows:
If more than one acceptance filter matches, the FILHIT
- 101 = Acceptance Filter 5 (RXF5) bits will encode the binary value of the lowest
- 100 = Acceptance Filter 4 (RXF4) numbered filter that matched. For example, if filter
- 011 = Acceptance Filter 3 (RXF3) RXF2 and filter RXF4 match, FILHIT will be loaded with
the value for RXF2. This essentially prioritizes the
- 010 = Acceptance Filter 2 (RXF2)
acceptance filters with a lower-numbered filter having
- 001 = Acceptance Filter 1 (RXF1) higher priority. Messages are compared to filters in
- 000 = Acceptance Filter 0 (RXF0) ascending order of filter number. This also ensures that
the message will only be received into one buffer. This
Note: 000 and 001 can only occur if the BUKT bit
implies that RXB0 has a higher priority than RXB1.
in RXB0CTRL is set, allowing RXB0
messages to roll over into RXB1. 4.5.5 CONFIGURING THE MASKS AND
RXB0CTRL contains two copies of the BUKT bit and FILTERS
the FILHIT<0> bit.
The mask and filter registers can only be modified
The coding of the BUKT bit enables these three bits to when the MCP2515 is in Configuration mode (see
be used similarly to the RXB1CTRL.FILHIT bits and to Section 10.0 “Modes of Operation”).
distinguish a hit on filter RXF0 and RXF1 in either
RXB0 or after a roll over into RXB1. Note: The mask and filter registers read all '0'
- 111 = Acceptance Filter 1 (RXB1) when in any mode except Configuration
mode.
- 110 = Acceptance Filter 0 (RXB1)
- 001 = Acceptance Filter 1 (RXB0)
- 000 = Acceptance Filter 0 (RXB0)

FIGURE 4-5: MESSAGE ACCEPTANCE MASK AND FILTER OPERATION

Acceptance Filter Register Acceptance Mask Register

RXFn0 RXMn0

RXMn1 RxRqst
RXFn1

RXFnn RXMnn

Message Assembly Buffer

Identifier

 2003-2012 Microchip Technology Inc. DS21801G-page 33

MCP2515
REGISTER 4-10: RXFnSIDH – FILTER n STANDARD IDENTIFIER HIGH
(ADDRESS: 00h, 04h, 08h, 10h, 14h, 18h)
R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x
SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3
bit 7 bit 0

Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 7-0 SID<10:3>: Standard Identifier Filter bits

These bits hold the filter bits to be applied to bits <10:3> of the Standard Identifier portion of a received
message

Note: The mask and filter registers read all '0' when in any mode except Configuration mode.

REGISTER 4-11: RXFnSIDL – FILTER n STANDARD IDENTIFIER LOW

(ADDRESS: 01h, 05h, 09h, 11h, 15h, 19h)
R/W-x R/W-x R/W-x U-0 R/W-x U-0 R/W-x R/W-x
SID2 SID1 SID0 — EXIDE — EID17 EID16
bit 7 bit 0

Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 7-5 SID<2:0>: Standard Identifier Filter bits

These bits hold the filter bits to be applied to bits <2:0> of the Standard Identifier portion of a received
message
bit 4 Unimplemented: Reads as ‘0’
bit 3 EXIDE: Extended Identifier Enable bit
1 = Filter is applied only to Extended Frames
0 = Filter is applied only to Standard Frames
bit 2 Unimplemented: Reads as ‘0’
bit 1-0 EID<17:16>: Extended Identifier Filter bits
These bits hold the filter bits to be applied to bits <17:16> of the Extended Identifier portion of a
received message

Note: The mask and filter registers read all '0' when in any mode except Configuration mode.

DS21801G-page 34  2003-2012 Microchip Technology Inc.

 MCP2515
REGISTER 4-12: RXFnEID8 – FILTER n EXTENDED IDENTIFIER HIGH
(ADDRESS: 02h, 06h, 0Ah, 12h, 16h, 1Ah)
R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x
EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8
bit 7 bit 0

Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 7-0 EID<15:8>: Extended Identifier bits

These bits hold the filter bits to be applied to bits <15:8> of the Extended Identifier portion of a received
message or to byte 0 in received data if corresponding RXM = 00 and EXIDE = 0

Note: The mask and filter registers read all '0' when in any mode except Configuration mode.

REGISTER 4-13: RXFnEID0 – FILTER n EXTENDED IDENTIFIER LOW

(ADDRESS: 03h, 07h, 0Bh, 13h, 17h, 1Bh)
R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x
EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0
bit 7 bit 0

Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 7-0 EID<7:0>: Extended Identifier bits

These bits hold the filter bits to be applied to bits <7:0> of the Extended Identifier portion of a received
message or to byte 1 in received data if corresponding RXM = 00 and EXIDE = 0.

Note: The mask and filter registers read all '0' when in any mode except Configuration mode.

REGISTER 4-14: RXMnSIDH – MASK n STANDARD IDENTIFIER HIGH

(ADDRESS: 20h, 24h)
R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0
SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3
bit 7 bit 0

Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 7-0 SID<10:3>: Standard Identifier Mask bits

These bits hold the mask bits to be applied to bits <10:3> of the Standard Identifier portion of a received
message

Note: The mask and filter registers read all '0' when in any mode except Configuration mode.

 2003-2012 Microchip Technology Inc. DS21801G-page 35

MCP2515
REGISTER 4-15: RXMnSIDL – MASK n STANDARD IDENTIFIER LOW
(ADDRESS: 21h, 25h)
R/W-0 R/W-0 R/W-0 U-0 U-0 U-0 R/W-0 R/W-0
SID2 SID1 SID0 — — — EID17 EID16
bit 7 bit 0

Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 7-5 SID<2:0>: Standard Identifier Mask bits

These bits hold the mask bits to be applied to bits<2:0> of the Standard Identifier portion of a received
message
bit 4-2 Unimplemented: Reads as ‘0’
bit 1-0 EID<17:16>: Extended Identifier Mask bits
These bits hold the mask bits to be applied to bits <17:16> of the Extended Identifier portion of a
received message

Note: The mask and filter registers read all '0' when in any mode except Configuration mode.
\

REGISTER 4-16: RXMnEID8 – MASK n EXTENDED IDENTIFIER HIGH

(ADDRESS: 22h, 26h)
R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0
EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8
bit 7 bit 0

Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 7-0 EID<15:8>: Extended Identifier bits

These bits hold the filter bits to be applied to bits <15:8> of the Extended Identifier portion of a received
message. If corresponding RXM = 00 and EXIDE = 0, these bits are applied to byte 0 in received data

Note: The mask and filter registers read all '0' when in any mode except Configuration mode.

DS21801G-page 36  2003-2012 Microchip Technology Inc.

 MCP2515
REGISTER 4-17: RXMnEID0 – MASK n EXTENDED IDENTIFIER LOW
(ADDRESS: 23h, 27h)
R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0
EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0
bit 7 bit 0

Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 7-0 EID<7:0>: Extended Identifier Mask bits

These bits hold the filter bits to be applied to bits <7:0> of the Extended Identifier portion of a received
message. If corresponding RXM = 00 and EXIDE = 0, these bits are applied to byte 1 in received data.

Note: The mask and filter registers read all '0' when in any mode except Configuration mode.

 2003-2012 Microchip Technology Inc. DS21801G-page 37

MCP2515
NOTES:

DS21801G-page 38  2003-2012 Microchip Technology Inc.

 MCP2515
5.0 BIT TIMING 5.1 The CAN Bit TIme
All nodes on a given CAN bus must have the same All devices on the CAN bus must use the same bit rate.
nominal bit rate. The CAN protocol uses Non Return to However, all devices are not required to have the same
Zero (NRZ) coding, which does not encode a clock master oscillator clock frequency. For the different
within the data stream. Therefore, the receive clock clock frequencies of the individual devices, the bit rate
must be recovered by the receiving nodes and has to be adjusted by appropriately setting the Baud
synchronized to the transmitter’s clock. Rate Prescaler and number of time quanta in each
segment.
As oscillators and transmission times may vary from
node to node, the receiver must have some type of The CAN bit time is made up of non-overlapping
Phase Lock Loop (PLL) synchronized to data segments. Each of these segments are made up of
transmission edges to synchronize and maintain the integer units called Time Quanta (TQ), explained later
receiver clock. Since the data is NRZ-coded, it is in this data sheet. The Nominal Bit Rate (NBR) is
necessary to include bit-stuffing to ensure that an edge defined in the CAN specification as the number of bits
occurs at least every six bit times to maintain the Digital per second transmitted by an ideal transmitter with no
Phase Lock Loop (DPLL) synchronization. resynchronization. It can be described with the
equation:
The bit timing of the MCP2515 is implemented using a
DPLL that is configured to synchronize to the incoming
data, as well as provide the nominal timing for the EQUATION 5-1:
transmitted data. The DPLL breaks each bit time into 1
NBR = fbit = -------
multiple segments made up of minimal periods of time, t bit
called the Time Quanta (TQ).
Bus timing functions executed within the bit time frame
(such as synchronization to the local oscillator, network Nominal Bit Time
transmission delay compensation and sample point
The Nominal Bit Time (NBT) (tbit) is made up of non-
positioning) are defined by the programmable bit timing
overlapping segments (Figure 5-1). Therefore, the
logic of the DPLL.
NBT is the summation of the following segments:

t bit = t SyncSeg + t PropSeg + t PS1 + t PS2

Associated with the NBT are the sample point,

Synchronization Jump Width (SJW) and Information
Processing Time (IPT), which are explained later.

SYNCHRONIZATION SEGMENT
The Synchronization Segment (SyncSeg) is the first
segment in the NBT and is used to synchronize the
nodes on the bus. Bit edges are expected to occur
within the SyncSeg. This segment is fixed at 1 TQ.

FIGURE 5-1: CAN BIT TIME SEGMENTS

SyncSeg PropSeg PhaseSeg1 (PS1) PhaseSeg2 (PS2)

Sample
Point
Nominal Bit Time (NBT), tbit

 2003-2012 Microchip Technology Inc. DS21801G-page 39

MCP2515
PROPAGATION SEGMENT Therefore:
The Propagation Segment (PropSeg) exists to
PS2 min = IPT = 2TQ
compensate for physical delays between nodes. The
propagation delay is defined as twice the sum of the
signal’s propagation time on the bus line, including the
delays associated with the bus driver. The PropSeg is SYNCHRONIZATION JUMP WIDTH
programmable from 1-8 TQ. The Synchronization Jump Width (SJW) adjusts the bit
clock as necessary by 1-4 TQ (as configured) to
PHASE SEGMENT 1 (PS1) AND PHASE maintain synchronization with the transmitted
SEGMENT 2 (PS2) message. Synchronization is covered in more detail
The two phase segments, PS1 and PS2, are used to later in this data sheet.
compensate for edge phase errors on the bus. PS1 can
be lengthened (or PS2 shortened) by resyncronization. Time Quantum
PS1 is programmable from 1-8 TQ and PS2 is
Each of the segments that make up a bit time are made
programmable from 2-8 TQ.
up of integer units called Time Quanta (TQ). The length
SAMPLE POINT of each Time Quantum is based on the oscillator period
(tOSC). The base TQ equals twice the oscillator period.
The sample point is the point in the bit time at which the Figure 5-2 shows how the bit period is derived from
logic level is read and interpreted. The sample point is TOSC and TQ. The TQ length equals one TQ clock
located at the end of PS1. The exception to this rule is period (tBRPCLK), which is programmable using a
if the sample mode is configured to sample three times programmable prescaler, called the Baud Rate
per bit. In this case, while the bit is still sampled at the Prescaler (BRP). This is illustrated in the following
end of PS1, two additional samples are taken at one- equation:
half TQ intervals prior to the end of PS1, with the value
of the bit being determined by a majority decision.
EQUATION 5-2:
INFORMATION PROCESSING TIME 2  BRP
TQ = 2  BRP  T OSC = -------------------
The Information Processing Time (IPT) is the time F OSC
required for the logic to determine the bit level of a
sampled bit. The IPT begins at the sample point, is Where: BRP equals the configuration as shown in
measured in TQ and is fixed at 2 TQ for the Microchip Register 5-1.
CAN module. Since PS2 also begins at the sample
point and is the last segment in the bit time, it is
required that the PS2 minimum is not less than the IPT.

FIGURE 5-2: TQ AND THE BIT PERIOD

tOSC

TBRPCLK

Sync PropSeg PS1 PS2

tBIT (fixed) (Programmable) (Programmable) (Programmable)

TQ
(tTQ)

CAN Bit Time

DS21801G-page 40  2003-2012 Microchip Technology Inc.

 MCP2515
5.2 Synchronization 5.2.2.2 No Phase Error (e = 0)
To compensate for phase shifts between the oscillator If the magnitude of the phase error is less than or equal
frequencies of each of the nodes on the bus, each CAN to the programmed value of the SJW, the effect of a
controller must be able to synchronize to the relevant resynchronization is the same as that of a hard
signal edge of the incoming signal. Synchronization is synchronization.
the process by which the DPLL function is
implemented. 5.2.2.3 Positive Phase Error (e > 0)
When an edge in the transmitted data is detected, the If the magnitude of the phase error is larger than the
logic will compare the location of the edge to the SJW and, if the phase error is positive, PS1 is
expected time (SyncSeg). The circuit will then adjust lengthened by an amount equal to the SJW.
the values of PS1 and PS2 as necessary.
5.2.2.4 Negative Phase Error (e < 0)
There are two mechanisms used for synchronization:
If the magnitude of the phase error is larger than the
1. Hard synchronization resynchronization jump width and the phase error is
2. Resynchronization negative, PS2 is shortened by an amount equal to the
SJW.
5.2.1 HARD SYNCHRONIZATION
Hard synchronization is only performed when there is a 5.2.3 SYNCHRONIZATION RULES
recessive-to-dominant edge during a BUS IDLE 1. Only recessive-to-dominant edges will be used
condition, indicating the start of a message. After hard for synchronization.
synchronization, the bit time counters are restarted with 2. Only one synchronization within one bit time is
SyncSeg. allowed.
Hard synchronization forces the edge that has 3. An edge will be used for synchronization only if
occurred to lie within the synchronization segment of the value detected at the previous sample point
the restarted bit time. Due to the rules of (previously read bus value) differs from the bus
synchronization, if a hard synchronization occurs, there value immediately after the edge.
will not be a resynchronization within that bit time. 4. A transmitting node will not resynchronize on a
5.2.2 RESYNCHRONIZATION positive phase error (e > 0).
5. If the absolute magnitude of the phase error is
As a result of resynchronization, PS1 may be
greater than the SJW, the appropriate phase
lengthened or PS2 may be shortened. The amount of
segment will adjust by an amount equal to the
lengthening or shortening of the phase buffer segments
SJW.
has an upper-bound, given by the Synchronization
Jump Width (SJW).
The value of the SJW will be added to PS1 or
subtracted from PS2 (see Figure 5-3). The SJW
represents the loop filtering of the DPLL. The SJW is
programmable between 1 TQ and 4 TQ.

5.2.2.1 Phase Errors

The NRZ bit coding method does not encode a clock
into the message. Clocking information will only be
derived from recessive-to-dominant transitions. The
property which states that only a fixed maximum
number of successive bits have the same value (bit-
stuffing) ensures resynchronization to the bit stream
during a frame.
The phase error of an edge is given by the position of
the edge relative to SyncSeg, measured in TQ. The
phase error is defined in magnitude of TQ as follows:
• e = 0 if the edge lies within SYNCSEG
• e > 0 if the edge lies before the SAMPLE POINT
(TQ is added to PS1)
• e < 0 if the edge lies after the SAMPLE POINT of
the previous bit (TQ is subtracted from PS2)

 2003-2012 Microchip Technology Inc. DS21801G-page 41

MCP2515
FIGURE 5-3: SYNCHRONIZING THE BIT TIME

Input Signal (e = 0)

PhaseSeg2 (PS2)
SyncSeg PropSeg PhaseSeg1 (PS1)
SJW (PS2)
SJW (PS1)
Sample
Point

Nominal Bit Time (NBT)

No Resynchronization (e = 0)

Input Signal
(e > 0)

PhaseSeg2 (PS2)
SyncSeg PropSeg PhaseSeg1 (PS1)
SJW (PS2)
SJW (PS1)
Sample
Point
Nominal Bit Time (NBT)

Actual Bit Time

Resynchronization to a Slower Transmitter (e > 0)

Input Signal (e < 0)

PhaseSeg2 (PS2)
SyncSeg PropSeg PhaseSeg1 (PS1)
SJW (PS2)
SJW (PS1)
Sample
Point

Nominal Bit Time (NBT)

Actual Bit Time

Resynchronization to a Faster Transmitter (e < 0)

DS21801G-page 42  2003-2012 Microchip Technology Inc.

 MCP2515
5.3 Programming Time Segments 5.5 Bit Timing Configuration
Some requirements for programming of the time
Registers
segments: The configuration registers (CNF1, CNF2, CNF3)
• PropSeg + PS1 >= PS2 control the bit timing for the CAN bus interface. These
• PropSeg + PS1 >= TDELAY registers can only be modified when the MCP2515 is in
Configuration mode (see Section 10.0 “Modes of
• PS2 > SJW
Operation”).
For example, assuming that a 125 kHz CAN baud rate
with FOSC = 20 MHz is desired: 5.5.1 CNF1
TOSC = 50 ns, choose BRP<5:0> = 04h, then The BRP<5:0> bits control the Baud Rate Prescaler.
TQ = 500 ns. To obtain 125 kHz, the bit time must be 16 These bits set the length of TQ relative to the OSC1
TQ. input frequency, with the minimum TQ length being
Typically, the sampling of the bit should take place at 2 TOSC (when BRP<5:0> = ‘b000000’). The
about 60-70% of the bit time, depending on the system SJW<1:0> bits select the SJW in terms of number of
parameters. Also, typically, the TDELAY is 1-2 TQ. TQs.

SyncSeg = 1 TQ and PropSeg = 2 TQ. So setting 5.5.2 CNF2

PS1 = 7 TQ would place the sample at 10 TQ after the
The PRSEG<2:0> bits set the length (in TQ’s) of the
transition. This would leave 6 TQ for PS2.
propagation segment. The PHSEG1<2:0> bits set the
Since PS2 is 6, according to the rules, SJW could be a length (in TQ’s) of PS1.
maximum of 4 TQ. However, a large SJW is typically
The SAM bit controls how many times the RXCAN pin
only necessary when the clock generation of the differ-
is sampled. Setting this bit to a ‘1’ causes the bus to be
ent nodes is inaccurate or unstable, such as using
sampled three times: twice at TQ/2 before the sample
ceramic resonators. So a SJW of 1 is usually enough.
point and once at the normal sample point (which is at
5.4 Oscillator Tolerance the end of PS1). The value of the bus is determined to
be the majority sampled. If the SAM bit is set to a ‘0’,
The bit timing requirements allow ceramic resonators the RXCAN pin is sampled only once at the sample
to be used in applications with transmission rates of up point.
to 125 kbit/sec as a rule of thumb. For the full bus The BTLMODE bit controls how the length of PS2 is
speed range of the CAN protocol, a quartz oscillator is determined. If this bit is set to a ‘1’, the length of PS2 is
required. A maximum node-to-node oscillator variation determined by the PHSEG2<2:0> bits of CNF3 (see
of 1.7% is allowed. Section 5.5.3 “CNF3”). If the BTLMODE bit is set to a
‘0’, the length of PS2 is greater than that of PS1 and the
information processing time (which is fixed at 2 TQ for
the MCP2515).

5.5.3 CNF3
The PHSEG2<2:0> bits set the length (in TQ’s) of PS2,
if the CNF2.BTLMODE bit is set to a ‘1’. If the
BTLMODE bit is set to a ‘0’, the PHSEG2<2:0> bits
have no effect.

 2003-2012 Microchip Technology Inc. DS21801G-page 43

MCP2515
REGISTER 5-1: CNF1 – CONFIGURATION 1 (ADDRESS: 2Ah)
R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0
SJW1 SJW0 BRP5 BRP4 BRP3 BRP2 BRP1 BRP0
bit 7 bit 0

Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 7-6 SJW<1:0>: Synchronization Jump Width Length bits

11 = Length = 4 x TQ
10 = Length = 3 x TQ
01 = Length = 2 x TQ
00 = Length = 1 x TQ
bit 5-0 BRP<5:0>: Baud Rate Prescaler bits
TQ = 2 x (BRP + 1)/FOSC

REGISTER 5-2: CNF2 – CONFIGURATION 1 (ADDRESS: 29h)

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0
BTLMODE SAM PHSEG12 PHSEG11 PHSEG10 PRSEG2 PRSEG1 PRSEG0
bit 7 bit 0

Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 7 BTLMODE: PS2 Bit Time Length bit

1 = Length of PS2 determined by PHSEG22:PHSEG20 bits of CNF3
0 = Length of PS2 is the greater of PS1 and IPT (2 TQ)
bit 6 SAM: Sample Point Configuration bit
1 = Bus line is sampled three times at the sample point
0 = Bus line is sampled once at the sample point
bit 5-3 PHSEG1<2:0>: PS1 Length bits
(PHSEG1 + 1) x TQ
bit 2-0 PRSEG<2:0>: Propagation Segment Length bits
(PRSEG + 1) x TQ

DS21801G-page 44  2003-2012 Microchip Technology Inc.

 MCP2515
REGISTER 5-3: CNF3 - CONFIGURATION 1 (ADDRESS: 28h)
R/W-0 R/W-0 U-0 U-0 U-0 R/W-0 R/W-0 R/W-0
SOF WAKFIL — — — PHSEG22 PHSEG21 PHSEG20
bit 7 bit 0

Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 7 SOF: Start-of-Frame signal bit

If CANCTRL.CLKEN = 1:
1 = CLKOUT pin enabled for SOF signal
0 = CLKOUT pin enabled for clockout function
If CANCTRL.CLKEN = 0, Bit is don’t care.
bit 6 WAKFIL: Wake-up Filter bit
1 = Wake-up filter enabled
0 = Wake-up filter disabled
bit 5-3 Unimplemented: Reads as ‘0’
bit 2-0 PHSEG2<2:0>: PS2 Length bits
(PHSEG2 + 1) x TQ
Minimum valid setting for PS2 is 2 TQ

 2003-2012 Microchip Technology Inc. DS21801G-page 45

MCP2515
NOTES:

DS21801G-page 46  2003-2012 Microchip Technology Inc.

 MCP2515
6.0 ERROR DETECTION 6.6 Error States
The CAN protocol provides sophisticated error Detected errors are made known to all other nodes via
detection mechanisms. The following errors can be error frames. The transmission of the erroneous mes-
detected. sage is aborted and the frame is repeated as soon as
possible. Furthermore, each CAN node is in one of the
6.1 CRC Error three error states according to the value of the internal
error counters:
With the Cyclic Redundancy Check (CRC), the
transmitter calculates special check bits for the bit 1. Error-active
sequence from the start of a frame until the end of the 2. Error-passive
data field. This CRC sequence is transmitted in the 3. Bus-off (transmitter only)
CRC Field. The receiving node also calculates the
The error-active state is the usual state where the node
CRC sequence using the same formula and performs
can transmit messages and active error frames (made
a comparison to the received sequence. If a mismatch
of dominant bits) without any restrictions.
is detected, a CRC error has occurred and an error
frame is generated. The message is repeated. In the error-passive state, messages and passive error
frames (made of recessive bits) may be transmitted.
6.2 Acknowledge Error The bus-off state makes it temporarily impossible for
In the acknowledge field of a message, the transmitter the station to participate in the bus communication.
checks if the acknowledge slot (which has been sent During this state, messages can neither be received or
out as a recessive bit) contains a dominant bit. If not, no transmitted. Only transmitters can go bus-off.
other node has received the frame correctly. An
acknowledge error has occurred, an error frame is
6.7 Error Modes and Error Counters
generated and the message will have to be repeated. The MCP2515 contains two error counters: the
Receive Error Counter (REC) (see Register 6-2) and
6.3 Form Error the Transmit Error Counter (TEC) (see Register 6-1).
If a node detects a dominant bit in one of the four The values of both counters can be read by the MCU.
segments (including end-of-frame, interframe space, These counters are incremented/decremented in
acknowledge delimiter or CRC delimiter), a form error accordance with the CAN bus specification.
has occurred and an error frame is generated. The The MCP2515 is error-active if both error counters are
message is repeated. below the error-passive limit of 128.
It is error-passive if at least one of the error counters
6.4 Bit Error equals or exceeds 128.
A bit error occurs if a transmitter detects the opposite It goes to bus-off if the TEC exceeds the bus-off limit of
bit level to what it transmitted (i.e., transmitted a 255. The device remains in this state until the bus-off
dominant and detected a recessive, or transmitted a recovery sequence is received. The bus-off recovery
recessive and detected a dominant). sequence consists of 128 occurrences of 11
Exception: In the case where the transmitter sends a consecutive recessive bits (see Figure 6-1).
recessive bit and a dominant bit is detected during the
arbitration field and the acknowledge slot, no bit error is Note: The MCP2515, after going bus-off, will
generated because normal arbitration is occurring. recover back to error-active without any
intervention by the MCU if the bus remains
6.5 Stuff Error idle for 128 x 11 bit times. If this is not
desired, the error interrupt Service
lf, between the start-of-frame and the CRC delimiter, Routine should address this.
six consecutive bits with the same polarity are
The Current Error mode of the MCP2515 can be read
detected, the bit-stuffing rule has been violated. A stuff
by the MCU via the EFLG register (see Register 6-3).
error occurs and an error frame is generated. The
message is repeated. Additionally, there is an error state warning flag bit
(EFLG:EWARN) which is set if at least one of the error
counters equals or exceeds the error warning limit of
96. EWARN is reset if both error counters are less than
the error warning limit.

 2003-2012 Microchip Technology Inc. DS21801G-page 47

MCP2515
FIGURE 6-1: ERROR MODES STATE DIAGRAM

RESET

REC < 127 or Error-Active

TEC < 127
128 occurrences of
11 consecutive
REC > 127 or “recessive” bits
TEC > 127

Error-Passive

TEC > 255

Bus-Off

REGISTER 6-1: TEC – TRANSMIT ERROR COUNTER

(ADDRESS: 1Ch)
R-0 R-0 R-0 R-0 R-0 R-0 R-0 R-0
TEC7 TEC6 TEC5 TEC4 TEC3 TEC2 TEC1 TEC0
bit 7 bit 0

Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 7-0 TEC<7:0>: Transmit Error Count bits

REGISTER 6-2: REC – RECEIVER ERROR COUNTER

(ADDRESS: 1Dh)
R-0 R-0 R-0 R-0 R-0 R-0 R-0 R-0
REC7 REC6 REC5 REC4 REC3 REC2 REC1 REC0
bit 7 bit 0

Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 7-0 REC<7:0>: Receive Error Count bits

DS21801G-page 48  2003-2012 Microchip Technology Inc.

 MCP2515
REGISTER 6-3: EFLG – ERROR FLAG
(ADDRESS: 2Dh)
R/W-0 R/W-0 R-0 R-0 R-0 R-0 R-0 R-0
RX1OVR RX0OVR TXBO TXEP RXEP TXWAR RXWAR EWARN
bit 7 bit 0

Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 7 RX1OVR: Receive Buffer 1 Overflow Flag bit

- Set when a valid message is received for RXB1 and CANINTF.RX1IF = 1
- Must be reset by MCU
bit 6 RX0OVR: Receive Buffer 0 Overflow Flag bit
- Set when a valid message is received for RXB0 and CANINTF.RX0IF = 1
- Must be reset by MCU
bit 5 TXBO: Bus-Off Error Flag bit
- Bit set when TEC reaches 255
- Reset after a successful bus recovery sequence
bit 4 TXEP: Transmit Error-Passive Flag bit
- Set when TEC is equal to or greater than 128
- Reset when TEC is less than 128
bit 3 RXEP: Receive Error-Passive Flag bit
- Set when REC is equal to or greater than 128
- Reset when REC is less than 128
bit 2 TXWAR: Transmit Error Warning Flag bit
- Set when TEC is equal to or greater than 96
- Reset when TEC is less than 96
bit 1 RXWAR: Receive Error Warning Flag bit
- Set when REC is equal to or greater than 96
- Reset when REC is less than 96
bit 0 EWARN: Error Warning Flag bit
- Set when TEC or REC is equal to or greater than 96 (TXWAR or RXWAR = 1)
- Reset when both REC and TEC are less than 96

 2003-2012 Microchip Technology Inc. DS21801G-page 49

MCP2515
NOTES:

DS21801G-page 50  2003-2012 Microchip Technology Inc.

 MCP2515
7.0 INTERRUPTS 7.2 Transmit Interrupt
The MCP2515 has eight sources of interrupts. The When the transmit interrupt is enabled
CANINTE register contains the individual interrupt (CANINTE.TXnIE = 1), an interrupt will be generated on
enable bits for each interrupt source. The CANINTF the INT pin once the associated transmit buffer
register contains the corresponding interrupt flag bit for becomes empty and is ready to be loaded with a new
each interrupt source. When an interrupt occurs, the message. The CANINTF.TXnIF bit will be set to indicate
INT pin is driven low by the MCP2515 and will remain the source of the interrupt. The interrupt is cleared by
low until the interrupt is cleared by the MCU. An clearing the TXnIF bit.
interrupt can not be cleared if the respective condition
still prevails. 7.3 Receive Interrupt
It is recommended that the Bit Modify command be When the receive interrupt is enabled
used to reset flag bits in the CANINTF register rather (CANINTE.RXnIE = 1), an interrupt will be generated
than normal write operations. This is done to prevent on the INT pin once a message has been successfully
unintentionally changing a flag that changes during the received and loaded into the associated receive buffer.
Write command, potentially causing an interrupt to be This interrupt is activated immediately after receiving
missed. the EOF field. The CANINTF.RXnIF bit will be set to
It should be noted that the CANINTF flags are indicate the source of the interrupt. The interrupt is
read/write and an interrupt can be generated by the cleared by clearing the RXnIF bit.
MCU setting any of these bits, provided the associated
CANINTE bit is also set. 7.4 Message Error Interrupt
When an error occurs during the transmission or
7.1 Interrupt Code Bits reception of a message, the message error flag
The source of a pending interrupt is indicated in the (CANINTF.MERRF) will be set and, if the
CANSTAT.ICOD (interrupt code) bits, as indicated in CANINTE.MERRE bit is set, an interrupt will be
Register 10-2. In the event that multiple interrupts generated on the INT pin. This is intended to be used
occur, the INT will remain low until all interrupts have to facilitate baud rate determination when used in
been reset by the MCU. The CANSTAT.ICOD bits will conjunction with Listen-Only mode.
reflect the code for the highest priority interrupt that is
currently pending. Interrupts are internally prioritized 7.5 Bus Activity Wake-up Interrupt
such that the lower the ICOD value, the higher the When the MCP2515 is in Sleep mode and the bus activity
interrupt priority. Once the highest priority interrupt wake-up interrupt is enabled (CANINTE.WAKIE = 1), an
condition has been cleared, the code for the next interrupt will be generated on the INT pin and the
highest priority interrupt that is pending (if any) will be CANINTF.WAKIF bit will be set when activity is detected
reflected by the ICOD bits (see Table 7-1). Only those on the CAN bus. This interrupt causes the MCP2515 to
interrupt sources that have their associated CANINTE exit Sleep mode. The interrupt is reset by clearing the
enable bit set will be reflected in the ICOD bits. WAKIF bit.

TABLE 7-1: ICOD<2:0> DECODE Note: The MCP2515 wakes up into Listen-Only
mode.
ICOD<2:0> Boolean Expression
7.6 Error Interrupt
000 ERR•WAK•TX0•TX1•TX2•RX0•RX1
When the error interrupt is enabled
001 ERR
(CANINTE.ERRIE = 1), an interrupt is generated on
010 ERR•WAK the INT pin if an overflow condition occurs or if the error
state of the transmitter or receiver has changed. The
011 ERR•WAK•TX0 Error Flag (EFLG) register will indicate one of the
100 ERR•WAK•TX0•TX1 following conditions.

101 ERR•WAK•TX0•TX1•TX2 7.6.1 RECEIVER OVERFLOW

110 ERR•WAK•TX0•TX1•TX2•RX0 An overflow condition occurs when the MAB has
111 ERR•WAK•TX0•TX1•TX2•RX0•RX1 assembled a valid receive message (the message
meets the criteria of the acceptance filters) and the
Note: ERR is associated with CANINTE,ERRIE. receive buffer associated with the filter is not available
for loading of a new message. The associated
EFLG.RXnOVR bit will be set to indicate the overflow
condition. This bit must be cleared by the MCU.

 2003-2012 Microchip Technology Inc. DS21801G-page 51

MCP2515
7.6.2 RECEIVER WARNING 7.6.6 BUS-OFF
The REC has reached the MCU warning limit of 96. The TEC has exceeded 255 and the device has gone
to bus-off state.
7.6.3 TRANSMITTER WARNING
7.7 Interrupt Acknowledge
The TEC has reached the MCU warning limit of 96.
Interrupts are directly associated with one or more
7.6.4 RECEIVER ERROR-PASSIVE status flags in the CANINTF register. Interrupts are
The REC has exceeded the error-passive limit of 127 pending as long as one of the flags is set. Once an
and the device has gone to error-passive state. interrupt flag is set by the device, the flag can not be
reset by the MCU until the interrupt condition is
7.6.5 TRANSMITTER ERROR-PASSIVE removed.

The TEC has exceeded the error-passive limit of 127

and the device has gone to error-passive state.

REGISTER 7-1: CANINTE – INTERRUPT ENABLE

(ADDRESS: 2Bh)
R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0
MERRE WAKIE ERRIE TX2IE TX1IE TX0IE RX1IE RX0IE
bit 7 bit 0

Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 7 MERRE: Message Error Interrupt Enable bit

1 = Interrupt on error during message reception or transmission
0 = Disabled
bit 6 WAKIE: Wake-up Interrupt Enable bit
1 = Interrupt on CAN bus activity
0 = Disabled
bit 5 ERRIE: Error Interrupt Enable bit (multiple sources in EFLG register)
1 = Interrupt on EFLG error condition change
0 = Disabled
bit 4 TX2IE: Transmit Buffer 2 Empty Interrupt Enable bit
1 = Interrupt on TXB2 becoming empty
0 = Disabled
bit 3 TX1IE: Transmit Buffer 1 Empty Interrupt Enable bit
1 = Interrupt on TXB1 becoming empty
0 = Disabled
bit 2 TX0IE: Transmit Buffer 0 Empty Interrupt Enable bit
1 = Interrupt on TXB0 becoming empty
0 = Disabled
bit 1 RX1IE: Receive Buffer 1 Full Interrupt Enable bit
1 = Interrupt when message received in RXB1
0 = Disabled
bit 0 RX0IE: Receive Buffer 0 Full Interrupt Enable bit
1 = Interrupt when message received in RXB0
0 = Disabled

DS21801G-page 52  2003-2012 Microchip Technology Inc.

 MCP2515
REGISTER 7-2: CANINTF – INTERRUPT FLAG
(ADDRESS: 2Ch)
R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0
MERRF WAKIF ERRIF TX2IF TX1IF TX0IF RX1IF RX0IF
bit 7 bit 0

Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 7 MERRF: Message Error Interrupt Flag bit

1 = Interrupt pending (must be cleared by MCU to reset interrupt condition)
0 = No interrupt pending
bit 6 WAKIF: Wake-up Interrupt Flag bit
1 = Interrupt pending (must be cleared by MCU to reset interrupt condition)
0 = No interrupt pending
bit 5 ERRIF: Error Interrupt Flag bit (multiple sources in EFLG register)
1 = Interrupt pending (must be cleared by MCU to reset interrupt condition)
0 = No interrupt pending
bit 4 TX2IF: Transmit Buffer 2 Empty Interrupt Flag bit
1 = Interrupt pending (must be cleared by MCU to reset interrupt condition)
0 = No interrupt pending
bit 3 TX1IF: Transmit Buffer 1 Empty Interrupt Flag bit
1 = Interrupt pending (must be cleared by MCU to reset interrupt condition)
0 = No interrupt pending
bit 2 TX0IF: Transmit Buffer 0 Empty Interrupt Flag bit
1 = Interrupt pending (must be cleared by MCU to reset interrupt condition)
0 = No interrupt pending
bit 1 RX1IF: Receive Buffer 1 Full Interrupt Flag bit
1 = Interrupt pending (must be cleared by MCU to reset interrupt condition)
0 = No interrupt pending
bit 0 RX0IF: Receive Buffer 0 Full Interrupt Flag bit
1 = Interrupt pending (must be cleared by MCU to reset interrupt condition)
0 = No interrupt pending

 2003-2012 Microchip Technology Inc. DS21801G-page 53

MCP2515
NOTES:

DS21801G-page 54  2003-2012 Microchip Technology Inc.

 MCP2515
8.0 OSCILLATOR 8.2 CLKOUT Pin
The MCP2515 is designed to be operated with a crystal The CLKOUT pin is provided to the system designer for
or ceramic resonator connected to the OSC1 and use as the main system clock or as a clock input for
OSC2 pins. The MCP2515 oscillator design requires other devices in the system. The CLKOUT has an inter-
the use of a parallel cut crystal. Use of a series cut nal prescaler which can divide FOSC by 1, 2, 4 and 8.
crystal may give a frequency out of the crystal The CLKOUT function is enabled and the prescaler is
manufacturer’s specifications. A typical oscillator circuit selected via the CANCNTRL register (see
is shown in Figure 8-1. The MCP2515 may also be Register 10-1).
driven by an external clock source connected to the
Note: The maximum frequency on CLKOUT is
OSC1 pin, as shown in Figure 8-2 and Figure 8-3.
specified as 25 MHz (See Table 13-5).
8.1 Oscillator Start-up Timer The CLKOUT pin will be active upon system Reset and
default to the slowest speed (divide by 8) so that it can
The MCP2515 utilizes an Oscillator Start-up Timer be used as the MCU clock.
(OST) that holds the MCP2515 in Reset to ensure that
the oscillator has stabilized before the internal state When Sleep mode is requested, the MCP2515 will
machine begins to operate. The OST maintains Reset drive sixteen additional clock cycles on the CLKOUT
for the first 128 OSC1 clock cycles after power-up or a pin before entering Sleep mode. The Idle state of the
wake-up from Sleep mode occurs. It should be noted CLKOUT pin in Sleep mode is low. When the CLKOUT
that no SPI protocol operations should be attempted function is disabled (CANCNTRL.CLKEN = 0) the
until after the OST has expired. CLKOUT pin is in a high-impedance state.
The CLKOUT function is designed to ensure that
thCLKOUT and tlCLKOUT timings are preserved when the
CLKOUT pin function is enabled, disabled or the
prescaler value is changed.

FIGURE 8-1: CRYSTAL/CERAMIC RESONATOR OPERATION

OSC1

C1 To internal logic

XTAL Sleep
RF(2)

RS(1)
C2 OSC2

Note 1: A series resistor (RS) may be required for AT strip-cut crystals.

2: The feedback resistor (RF ), is typically in the range of 2 to 10 M.

FIGURE 8-2: EXTERNAL CLOCK SOURCE

Clock from
OSC1
external system

(1)
Open OSC2

Note 1: A resistor to ground may be used to reduce system noise. This may increase system current.
2: Duty cycle restrictions must be observed (see Table 12-1).

 2003-2012 Microchip Technology Inc. DS21801G-page 55

MCP2515
FIGURE 8-3: EXTERNAL SERIES RESONANT CRYSTAL OSCILLATOR CIRCUIT(1)

330 k 330 k To Other

Devices
74AS04 74AS04 74AS04 MCP2510

OSC1
0.1 mF

XTAL

Note 1: Duty cycle restrictions must be observed (see Table 12-1).

TABLE 8-1: CAPACITOR SELECTION FOR TABLE 8-2: CAPACITOR SELECTION FOR
CERAMIC RESONATORS CRYSTAL OSCILLATOR
Typical Capacitor Values Used: Typical Capacitor
Osc Crystal Values Tested:
Mode Freq. OSC1 OSC2 Type(1)(4) Freq.(2)
C1 C2
HS 8.0 MHz 27 pF 27 pF
16.0 MHz 22 pF 22 pF HS 4 MHz 27 pF 27 pF
Capacitor values are for design guidance only: 8 MHz 22 pF 22 pF
These capacitors were tested with the resonators 20 MHz 15 pF 15 pF
listed below for basic start-up and operation. These Capacitor values are for design guidance only:
values are not optimized. These capacitors were tested with the crystals listed
Different capacitor values may be required to below for basic start-up and operation. These values
produce acceptable oscillator operation. The user are not optimized.
should test the performance of the oscillator over the Different capacitor values may be required to
expected VDD and temperature range for the produce acceptable oscillator operation. The user
application. should test the performance of the oscillator over the
See the notes following Table 8-2 for additional expected VDD and temperature range for the
information. application.
Resonators Used: See the notes following this Table for additional
4.0 MHz information.
8.0 MHz Crystals Used(3):
16.0 MHz 4.0 MHz
8.0 MHz
20.0 MHz

Note 1: While higher capacitance increases the

stability of the oscillator, it also increases
the start-up time.
2: Since each resonator/crystal has its own
characteristics, the user should consult
the resonator/crystal manufacturer for
appropriate values of external
components.
3: RS may be required to avoid overdriving
crystals with low drive level specification.
4: Always verify oscillator performance over
the VDD and temperature range that is
expected for the application.

DS21801G-page 56  2003-2012 Microchip Technology Inc.

 MCP2515
9.0 RESET
The MCP2515 differentiates between two Resets:
1. Hardware Reset – Low on RESET pin
2. SPI Reset – Reset via SPI command
Both of these Resets are functionally equivalent. It is
important to provide one of these two Resets after
power-up to ensure that the logic and registers are in
their default state. A hardware Reset can be achieved
automatically by placing an RC on the RESET pin (see
Figure 9-1). The values must be such that the device is
held in Reset for a minimum of 2 µs after VDD reaches
operating voltage, as indicated in the electrical
specification (tRL).

FIGURE 9-1: RESET PIN CONFIGURATION EXAMPLE

VDD VDD

D(1) R
R1(2)
RESET

Note 1: The diode D helps discharge the capacitor quickly when VDD powers down.
2: R1 = 1 k to 10 k will limit any current flowing into RESET from external
capacitor C, in the event of RESET pin breakdown due to Electrostatic
Discharge (ESD) or Electrical Overstress (EOS).

 2003-2012 Microchip Technology Inc. DS21801G-page 57

MCP2515
NOTES:

DS21801G-page 58  2003-2012 Microchip Technology Inc.

 MCP2515
10.0 MODES OF OPERATION When in Sleep mode, the MCP2515 stops its internal
oscillator. The MCP2515 will wake-up when bus activity
The MCP2515 has five modes of operation. These occurs or when the MCU sets, via the SPI interface, the
modes are: CANINTF.WAKIF bit to ‘generate’ a wake-up attempt
1. Configuration mode (the CANINTE.WAKIE bit must also be set in order for
2. Normal mode the wake-up interrupt to occur).
3. Sleep mode The TXCAN pin will remain in the recessive state while
4. Listen-Only mode the MCP2515 is in Sleep mode.
5. Loopback mode 10.2.1 WAKE-UP FUNCTIONS
The operational mode is selected via the The device will monitor the RXCAN pin for activity while
CANCTRL. REQOP bits (see Register 10-1). it is in Sleep mode. If the CANINTE.WAKIE bit is set,
When changing modes, the mode will not actually the device will wake-up and generate an interrupt.
change until all pending message transmissions are Since the internal oscillator is shut down while in Sleep
complete. The requested mode must be verified by mode, it will take some amount of time for the oscillator
reading the CANSTAT.OPMODE bits (see to start-up and the device to enable itself to receive
Register 10-2). messages. This Oscillator Start-up Timer (OST) is
defined as 128 TOSC.
10.1 Configuration Mode The device will ignore the message that caused the
wake-up from Sleep mode, as well as any messages
The MCP2515 must be initialized before activation.
that occur while the device is ‘waking up’. The device
This is only possible if the device is in the Configuration
will wake-up in Listen-Only mode. The MCU must set
mode. Configuration mode is automatically selected
Normal mode before the MCP2515 will be able to
after power-up, a Reset or can be entered from any
communicate on the bus.
other mode by setting the CANTRL.REQOP bits to
‘100’. When Configuration mode is entered, all error The device can be programmed to apply a low-pass
counters are cleared. Configuration mode is the only filter function to the RXCAN input line while in internal
mode where the following registers are modifiable: Sleep mode. This feature can be used to prevent the
device from waking up due to short glitches on the CAN
• CNF1, CNF2, CNF3
bus lines. The CNF3.WAKFIL bit enables or disables
• TXRTSCTRL the filter.
• Filter registers
• Mask registers 10.3 Listen-Only Mode

10.2 Sleep Mode Listen-Only mode provides a means for the MCP2515
to receive all messages (including messages with
The MCP2515 has an internal Sleep mode that is used errors) by configuring the RXBnCTRL.RXM<1:0> bits.
to minimize the current consumption of the device. The This mode can be used for bus monitor applications or
SPI interface remains active for reading even when the for detecting the baud rate in ‘hot plugging’ situations.
MCP2515 is in Sleep mode, allowing access to all For auto-baud detection, it is necessary that at least
registers. two other nodes are communicating with each other.
To enter Sleep mode, the mode request bits are set in The baud rate can be detected empirically by testing
the CANCTRL register (REQOP<2:0>). The different values until valid messages are received.
CANSTAT.OPMODE bits indicate operation mode. Listen-Only mode is a silent mode, meaning no
These bits should be read after sending the Sleep messages will be transmitted while in this mode
command to the MCP2515. The MCP2515 is active (including error flags or acknowledge signals). In
and has not yet entered Sleep mode until these bits Listen-Only mode, both valid and invalid messages will
indicate that Sleep mode has been entered. be received regardless of filters and masks or RXMn
When in internal Sleep mode, the wake-up interrupt is Receive Buffer mode bits. The error counters are reset
still active (if enabled). This is done so that the MCU and deactivated in this state. The Listen-Only mode is
can also be placed into a Sleep mode and use the activated by setting the mode request bits in the
MCP2515 to wake it up upon detecting activity on the CANCTRL register.
bus.

 2003-2012 Microchip Technology Inc. DS21801G-page 59

MCP2515
10.4 Loopback Mode 10.5 Normal Mode
Loopback mode will allow internal transmission of Normal mode is the standard operating mode of the
messages from the transmit buffers to the receive MCP2515. In this mode, the device actively monitors all
buffers without actually transmitting messages on the bus messages and generates Acknowledge bits, error
CAN bus. This mode can be used in system frames, etc. This is also the only mode in which the
development and testing. MCP2515 will transmit messages over the CAN bus.
In this mode, the ACK bit is ignored and the device will
allow incoming messages from itself just as if they were
coming from another node. The Loopback mode is a
silent mode, meaning no messages will be transmitted
while in this state (including error flags or Acknowledge
signals). The TXCAN pin will be in a recessive state.
The filters and masks can be used to allow only
particular messages to be loaded into the receive
registers. The masks can be set to all zeros to provide
a mode that accepts all messages. The Loopback
mode is activated by setting the mode request bits in
the CANCTRL register.

REGISTER 10-1: CANCTRL – CAN CONTROL REGISTER

(ADDRESS: XFh)
R/W-1 R/W-0 R/W-0 R/W-0 R/W-0 R/W-1 R/W-1 R/W-1
REQOP2 REQOP1 REQOP0 ABAT OSM CLKEN CLKPRE1 CLKPRE0
bit 7 bit 0

Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 7-5 REQOP<2:0>: Request Operation mode bits

000 = Set Normal Operation mode
001 = Set Sleep mode
010 = Set Loopback mode
011 = Set Listen-Only mode
100 = Set Configuration mode
All other values for REQOP bits are invalid and should not be used
On power-up, REQOP = b’111’
bit 4 ABAT: Abort All Pending Transmissions bit
1 = Request abort of all pending transmit buffers
0 = Terminate request to abort all transmissions
bit 3 OSM: One-Shot mode bit
1 = Enabled. Message will only attempt to transmit one time
0 = Disabled. Messages will reattempt transmission, if required
bit 2 CLKEN: CLKOUT Pin Enable bit
1 = CLKOUT pin enabled
0 = CLKOUT pin disabled (Pin is in high-impedance state)
bit 1-0 CLKPRE<1:0>: CLKOUT Pin Prescaler bits
00 = FCLKOUT = System Clock/1
01 = FCLKOUT = System Clock/2
10 = FCLKOUT = System Clock/4
11 = FCLKOUT = System Clock/8

DS21801G-page 60  2003-2012 Microchip Technology Inc.

 MCP2515
REGISTER 10-2: CANSTAT – CAN STATUS REGISTER
(ADDRESS: XEh)
R-1 R-0 R-0 U-0 R-0 R-0 R-0 U-0
OPMOD2 OPMOD1 OPMOD0 — ICOD2 ICOD1 ICOD0 —
bit 7 bit 0

Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

bit 7-5 OPMOD<2:0>: Operation mode bits

000 = Device is in the Normal Operation mode
001 = Device is in Sleep mode
010 = Device is in Loopback mode
011 = Device is in Listen-Only mode
100 = Device is in Configuration mode
bit 4 Unimplemented: Read as ‘0’
bit 3-1 ICOD<2:0>: Interrupt Flag Code bits
000 = No Interrupt
001 = Error Interrupt
010 = Wake-up Interrupt
011 = TXB0 Interrupt
100 = TXB1 Interrupt
101 = TXB2 Interrupt
110 = RXB0 Interrupt
111 = RXB1 Interrupt
bit 0 Unimplemented: Read as ‘0’

 2003-2012 Microchip Technology Inc. DS21801G-page 61

MCP2515
NOTES:

DS21801G-page 62  2003-2012 Microchip Technology Inc.

 MCP2515
11.0 REGISTER MAP reading and writing of data. Some specific control and
status registers allow individual bit modification using
The register map for the MCP2515 is shown in the SPI Bit Modify command. The registers that allow
Table 11-1. Address locations for each register are this command are shown as shaded locations in
determined by using the column (higher-order four Table 11-1. A summary of the MCP2515 control
bits) and row (lower-order four bits) values. The regis- registers is shown in Table 11-2.
ters have been arranged to optimize the sequential

TABLE 11-1: CAN CONTROLLER REGISTER MAP

Lower Higher-Order Address Bits
Address
Bits 0000 xxxx 0001 xxxx 0010 xxxx 0011 xxxx 0100 xxxx 0101 xxxx 0110 xxxx 0111 xxxx

0000 RXF0SIDH RXF3SIDH RXM0SIDH TXB0CTRL TXB1CTRL TXB2CTRL RXB0CTRL RXB1CTRL

0001 RXF0SIDL RXF3SIDL RXM0SIDL TXB0SIDH TXB1SIDH TXB2SIDH RXB0SIDH RXB1SIDH
0010 RXF0EID8 RXF3EID8 RXM0EID8 TXB0SIDL TXB1SIDL TXB2SIDL RXB0SIDL RXB1SIDL
0011 RXF0EID0 RXF3EID0 RXM0EID0 TXB0EID8 TXB1EID8 TXB2EID8 RXB0EID8 RXB1EID8
0100 RXF1SIDH RXF4SIDH RXM1SIDH TXB0EID0 TXB1EID0 TXB2EID0 RXB0EID0 RXB1EID0
0101 RXF1SIDL RXF4SIDL RXM1SIDL TXB0DLC TXB1DLC TXB2DLC RXB0DLC RXB1DLC
0110 RXF1EID8 RXF4EID8 RXM1EID8 TXB0D0 TXB1D0 TXB2D0 RXB0D0 RXB1D0
0111 RXF1EID0 RXF4EID0 RXM1EID0 TXB0D1 TXB1D1 TXB2D1 RXB0D1 RXB1D1
1000 RXF2SIDH RXF5SIDH CNF3 TXB0D2 TXB1D2 TXB2D2 RXB0D2 RXB1D2
1001 RXF2SIDL RXF5SIDL CNF2 TXB0D3 TXB1D3 TXB2D3 RXB0D3 RXB1D3
1010 RXF2EID8 RXF5EID8 CNF1 TXB0D4 TXB1D4 TXB2D4 RXB0D4 RXB1D4
1011 RXF2EID0 RXF5EID0 CANINTE TXB0D5 TXB1D5 TXB2D5 RXB0D5 RXB1D5
1100 BFPCTRL TEC CANINTF TXB0D6 TXB1D6 TXB2D6 RXB0D6 RXB1D6
1101 TXRTSCTRL REC EFLG TXB0D7 TXB1D7 TXB2D7 RXB0D7 RXB1D7
1110 CANSTAT CANSTAT CANSTAT CANSTAT CANSTAT CANSTAT CANSTAT CANSTAT
1111 CANCTRL CANCTRL CANCTRL CANCTRL CANCTRL CANCTRL CANCTRL CANCTRL
Note: Shaded register locations indicate that these allow the user to manipulate individual bits using the Bit Modify command.

TABLE 11-2: CONTROL REGISTER SUMMARY

Register Address POR/RST
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Name (Hex) Value
BFPCTRL 0C — — B1BFS B0BFS B1BFE B0BFE B1BFM B0BFM --00 0000
TXRTSCTRL 0D — — B2RTS B1RTS B0RTS B2RTSM B1RTSM B0RTSM --xx x000
CANSTAT xE OPMOD2 OPMOD1 OPMOD0 — ICOD2 ICOD1 ICOD0 — 100- 000-
CANCTRL xF REQOP2 REQOP1 REQOP0 ABAT OSM CLKEN CLKPRE1 CLKPRE0 1110 0111
TEC 1C Transmit Error Counter (TEC) 0000 0000
REC 1D Receive Error Counter (REC) 0000 0000
CNF3 28 SOF WAKFIL — — — PHSEG22 PHSEG21 PHSEG20 00-- -000
CNF2 29 BTLMODE SAM PHSEG12 PHSEG11 PHSEG10 PRSEG2 PRSEG1 PRSEG0 0000 0000
CNF1 2A SJW1 SJW0 BRP5 BRP4 BRP3 BRP2 BRP1 BRP0 0000 0000
CANINTE 2B MERRE WAKIE ERRIE TX2IE TX1IE TX0IE RX1IE RX0IE 0000 0000
CANINTF 2C MERRF WAKIF ERRIF TX2IF TX1IF TX0IF RX1IF RX0IF 0000 0000
EFLG 2D RX1OVR RX0OVR TXBO TXEP RXEP TXWAR RXWAR EWARN 0000 0000
TXB0CTRL 30 — ABTF MLOA TXERR TXREQ — TXP1 TXP0 -000 0-00
TXB1CTRL 40 — ABTF MLOA TXERR TXREQ — TXP1 TXP0 -000 0-00
TXB2CTRL 50 — ABTF MLOA TXERR TXREQ — TXP1 TXP0 -000 0-00
RXB0CTRL 60 — RXM1 RXM0 — RXRTR BUKT BUKT FILHIT0 -00- 0000
RXB1CTRL 70 — RSM1 RXM0 — RXRTR FILHIT2 FILHIT1 FILHIT0 -00- 0000

 2003-2012 Microchip Technology Inc. DS21801G-page 63

MCP2515
NOTES:

DS21801G-page 64  2003-2012 Microchip Technology Inc.

 MCP2515
12.0 SPI INTERFACE the same as the READ instruction (i.e., sequential reads
are possible). This instruction further reduces the SPI
12.1 Overview overhead by automatically clearing the associated
receive flag (CANINTF.RXnIF) when CS is raised at the
The MCP2515 is designed to interface directly with the end of the command.
Serial Peripheral Interface (SPI) port available on many
microcontrollers and supports Mode 0,0 and Mode 1,1. 12.5 WRITE Instruction
Commands and data are sent to the device via the SI
pin, with data being clocked in on the rising edge of The WRITE instruction is started by lowering the CS
SCK. Data is driven out by the MCP2515 (on the SO pin. The WRITE instruction is then sent to the MCP2515
line) on the falling edge of SCK. The CS pin must be followed by the address and at least one byte of data.
held low while any operation is performed. Table 12-1 It is possible to write to sequential registers by
shows the instruction bytes for all operations. Refer to continuing to clock in data bytes, as long as CS is held
Figure 12-10 and Figure 12-11 for detailed input and low. Data will actually be written to the register on the
output timing diagrams for both Mode 0,0 and Mode rising edge of the SCK line for the D0 bit. If the CS line
1,1 operation. is brought high before eight bits are loaded, the write
Note: The MCP2515 expects the first byte after will be aborted for that data byte and previous bytes in
lowering CS to be the instruction/ the command will have been written. Refer to the timing
command byte. This implies that CS must diagram in Figure 12-4 for a more detailed illustration of
be raised and then lowered again to the byte write sequence.
invoke another command.
12.6 LOAD TX BUFFER Instruction
12.2 RESET Instruction
The LOAD TX BUFFER instruction (Figure 12-5) elimi-
The RESET instruction can be used to re-initialize the nates the eight-bit address required by a normal Write
internal registers of the MCP2515 and set Configuration command. The eight-bit instruction sets the Address
mode. This command provides the same functionality, Pointer to one of six addresses to quickly write to a
via the SPI interface, as the RESET pin. transmit buffer that points to the “ID” or “data” address
The RESET instruction is a single-byte instruction that of any of the three transmit buffers.
requires selecting the device by pulling CS low,
sending the instruction byte and then raising CS. It is 12.7 REQUEST-TO-SEND (RTS)
highly recommended that the Reset command be sent Instruction
(or the RESET pin be lowered) as part of the power-on
initialization sequence. The RTS command can be used to initiate message
transmission for one or more of the transmit buffers.
12.3 READ Instruction The MCP2515 is selected by lowering the CS pin. The
RTS command byte is then sent. Shown in Figure 12-6,
The READ instruction is started by lowering the CS pin.
the last 3 bits of this command indicate which transmit
The READ instruction is then sent to the MCP2515
buffer(s) are enabled to send.
followed by the 8-bit address (A7 through A0). Next, the
data stored in the register at the selected address will This command will set the TxBnCTRL.TXREQ bit for
be shifted out on the SO pin. the respective buffer(s). Any or all of the last three bits
can be set in a single command. If the RTS command
The internal Address Pointer is automatically
is sent with nnn = 000, the command will be ignored.
incremented to the next address once each byte of
data is shifted out. Therefore, it is possible to read the
next consecutive register address by continuing to pro- 12.8 READ STATUS Instruction
vide clock pulses. Any number of consecutive register The READ STATUS instruction allows single instruction
locations can be read sequentially using this method. access to some of the often used status bits for
The read operation is terminated by raising the CS pin message reception and transmission.
(Figure 12-2).
The MCP2515 is selected by lowering the CS pin and
12.4 READ RX BUFFER Instruction the Read Status command byte, shown in Figure 12-8,
is sent to the MCP2515. Once the command byte is
The READ RX BUFFER instruction (Figure 12-3) pro- sent, the MCP2515 will return eight bits of data that
vides a means to quickly address a receive buffer for contain the status.
reading. This instruction reduces the SPI overhead by
If additional clocks are sent after the first eight bits are
one byte, the address byte. The command byte actually
transmitted, the MCP2515 will continue to output the
has four possible values that determine the Address
status bits as long as the CS pin is held low and clocks
Pointer location. Once the command byte is sent, the
are provided on SCK.
controller clocks out the data at the address location

 2003-2012 Microchip Technology Inc. DS21801G-page 65

MCP2515
Each status bit returned in this command may also be The part is selected by lowering the CS pin and the Bit
read by using the standard Read command with the Modify command byte is then sent to the MCP2515.
appropriate register address. The command is followed by the address of the
register, the mask byte and finally the data byte.
12.9 RX STATUS Instruction The mask byte determines which bits in the register will
be allowed to change. A ‘1’ in the mask byte will allow
The RX STATUS instruction (Figure 12-9) is used to
a bit in the register to change, while a ‘0’ will not.
quickly determine which filter matched the message
and message type (standard, extended, remote). After The data byte determines what value the modified bits
the command byte is sent, the controller will return in the register will be changed to. A ‘1’ in the data byte
8 bits of data that contain the status data. If more clocks will set the bit and a ‘0’ will clear the bit, provided that
are sent after the eight bits are transmitted, the the mask for that bit is set to a ‘1’ (see Figure 12-7).
controller will continue to output the same status bits as
FIGURE 12-1: BIT MODIFY
long as the CS pin stays low and clocks are provided.

Mask byte 0 0 1 1 0 1 0 1
12.10 BIT MODIFY Instruction
The BIT MODIFY instruction provides a means for set-
ting or clearing individual bits in specific status and con- Data byte X X 1 0 X 0 X 1
trol registers. This command is not available for all
registers. See Section 11.0 “Register Map” to
Previous
determine which registers allow the use of this
Register 0 1 0 1 0 0 0 1
command. Contents
Note: Executing the Bit Modify command on
Resulting
registers that are not bit-modifiable will Register 0 1 1 0 0 0 0 1
force the mask to FFh. This will allow byte- Contents
writes to the registers, not bit modify.

TABLE 12-1: SPI INSTRUCTION SET

Instruction Name Instruction Format Description
RESET 1100 0000 Resets internal registers to default state, set Configuration mode.
READ 0000 0011 Read data from register beginning at selected address.
READ RX BUFFER 1001 0nm0 When reading a receive buffer, reduces the overhead of a normal
Read command by placing the Address Pointer at one of four
locations, as indicated by ‘n,m’. Note: The associated RX flag bit
(CANINTF.RXnIF) will be cleared after bringing CS high.
WRITE 0000 0010 Write data to register beginning at selected address.
LOAD TX BUFFER 0100 0abc When loading a transmit buffer, reduces the overhead of a normal
Write command by placing the Address Pointer at one of six
locations as indicated by ‘a,b,c’.
RTS 1000 0nnn Instructs controller to begin message transmission sequence for
(Message any of the transmit buffers.
Request-To-Send)
1000 0nnn
Request-to-send for TXB2 Request-to-send for TXBO

Request-to-send for TXB1

READ STATUS 1010 0000 Quick polling command that reads several status bits for transmit
and receive functions.
RX STATUS 1011 0000 Quick polling command that indicates filter match and message
type (standard, extended and/or remote) of received message.
BIT MODIFY 0000 0101 Allows the user to set or clear individual bits in a particular
register. Note: Not all registers can be bit-modified with this
command. Executing this command on registers that are not bit-
modifiable will force the mask to FFh. See the register map in
Section 11.0 “Register Map” for a list of the registers that apply.

DS21801G-page 66  2003-2012 Microchip Technology Inc.

 MCP2515
FIGURE 12-2: READ INSTRUCTION

CS

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
SCK

Instruction Address Byte

SI 0 0 0 0 0 0 1 1 A7 6 5 4 3 2 1 A0 Don’t Care

Data Out
High-Impedance
SO 7 6 5 4 3 2 1 0

FIGURE 12-3: READ RX BUFFER INSTRUCTION

CS
n m Address Points to Address

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 0 0 Receive Buffer 0, 0x61

SCK Start at RXB0SIDH
0 1 Receive Buffer 0, 0x66
Instruction Start at RXB0D0
SI 1 0 0 1 0 n m 0 Don’t Care 1 0 Receive Buffer 1, 0x71
Start at RXB1SIDH
Data Out 1 1 Receive Buffer 1, 0x76
High-Impedance
SO 7 6 5 4 3 2 1 0 Start at RXB1D0

FIGURE 12-4: BYTE WRITE INSTRUCTION

CS

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
SCK

Instruction Address Byte Data Byte

SI 0 0 0 0 0 0 1 0 A7 6 5 4 3 2 1 A0 7 6 5 4 3 2 1 0

High-Impedance
SO

 2003-2012 Microchip Technology Inc. DS21801G-page 67

MCP2515
FIGURE 12-5: LOAD TX BUFFER

a b c Address Points to Addr

CS 0 0 0 TX buffer 0, Start at 0x31
TXB0SIDH
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 0 0 1 TX buffer 0, Start at 0x36
SCK TXB0D0
0 1 0 TX buffer 1, Start at 0x41
Instruction Data In TXB1SIDH
0 1 1 TX buffer 1, Start at 0x46
SI 0 1 0 0 0 a b c 7 6 5 4 3 2 1 0
TXB1D0
1 0 0 TX buffer 2, Start at 0x51
High-Impedance TXB2SIDH
SO
1 0 1 TX buffer 2, Start at 0x56
TXB2D0

FIGURE 12-6: REQUEST-TO-SEND (RTS) INSTRUCTION

CS

0 1 2 3 4 5 6 7
SCK

Instruction

SI 1 0 0 0 0 T2 T1 T0

High-Impedance
SO

FIGURE 12-7: BIT MODIFY INSTRUCTION

CS

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
SCK

Instruction Address Byte Mask Byte Data Byte

SI 0 0 0 0 0 1 0 1 A7 6 5 4 3 2 1 A0 7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0

High-Impedance
SO

Note: Not all registers can be accessed with

this command. See the register map for a
list of the registers that apply.

DS21801G-page 68  2003-2012 Microchip Technology Inc.

 MCP2515
FIGURE 12-8: READ STATUS INSTRUCTION

CS

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
SCK

Instruction

SI 1 0 1 0 0 0 0 0 Don’t Care

Repeat
Data Out Data Out
High-Impedance
SO 7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0

CANINTF.RX0IF
CANINTFL.RX1IF
TXB0CNTRL.TXREQ
CANINTF.TX0IF
TXB1CNTRL.TXREQ
CANINTF.TX1IF
TXB2CNTRL.TXREQ
CANINTF.TX2IF

FIGURE 12-9: RX STATUS INSTRUCTION

CS

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
SCK

Instruction

SI 1 0 1 1 0 0 0 0 Don’t Care

Repeat
Data Out Data Out
High-Impedance
SO 7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0

7 6 Received Message 4 3 Msg Type Received 2 1 0 Filter Match

0 0 No RX message 0 0 Standard data frame 0 0 0 RXF0
0 1 Message in RXB0 0 1 Standard remote frame 0 0 1 RXF1
1 0 Message in RXB1 1 0 Extended data frame 0 1 0 RXF2
1 1 Messages in both buffers* 1 1 Extended remote frame 0 1 1 RXF3
CANINTF.RXnIF bits are mapped to The extended ID bit is mapped to 1 0 0 RXF4
bits 7 and 6. bit 4. The RTR bit is mapped to 1 0 1 RXF5
bit 3.
1 1 0 RXF0 (rollover to RXB1)
* Buffer 0 has higher priority, therefore, RXB0 status is 1 1 1 RXF1 (rollover to RXB1)
reflected in bits 4:0.

 2003-2012 Microchip Technology Inc. DS21801G-page 69

MCP2515
FIGURE 12-10: SPI INPUT TIMING

3
CS
11
1 6 10
Mode 1,1 7 2
SCK Mode 0,0

4 5
SI
MSB in LSB in

SO High-Impedance

FIGURE 12-11: SPI OUTPUT TIMING

CS

2
8 9
SCK Mode 1,1
Mode 0,0

12
14
13
SO MSB out LSB out

Don’t Care
SI

DS21801G-page 70  2003-2012 Microchip Technology Inc.

 MCP2515
13.0 ELECTRICAL CHARACTERISTICS
13.1 Absolute Maximum Ratings †
VDD .............................................................................................................................................................................7.0V
All inputs and outputs w.r.t. VSS ..........................................................................................................-0.6V to VDD +1.0V
Storage temperature ...............................................................................................................................-65°C to +150°C
Ambient temperature with power applied................................................................................................-65°C to +125°C
Soldering temperature of leads (10 seconds) ....................................................................................................... +300°C

† Notice: Stresses above those listed under “Maximum Ratings” may cause permanent damage to the device. This
is a stress rating only and functional operation of the device at those or any other conditions above those indicated in
the operational listings of this specification is not implied. Exposure to maximum rating conditions for extended periods
may affect device reliability.

 2003-2012 Microchip Technology Inc. DS21801G-page 71

MCP2515
TABLE 13-1: DC CHARACTERISTICS
Industrial (I): TAMB = -40°C to +85°C VDD = 2.7V to 5.5V
DC Characteristics
Extended (E): TAMB = -40°C to +125°C VDD = 4.5V to 5.5V

Param.
No. Sym Characteristic Min Max Units Conditions

VDD Supply Voltage 2.7 5.5 V

VRET Register Retention Voltage 2.4 — V

High-Level Input Voltage

VIH RXCAN 2 VDD + 1 V

SCK, CS, SI, TXnRTS Pins 0.7 VDD VDD + 1 V

OSC1 0.85 VDD VDD V

RESET 0.85 VDD VDD V

Low-Level Input Voltage

VIL RXCAN, TXnRTS Pins -0.3 .15 VDD V

SCK, CS, SI -0.3 0.4 VDD V

OSC1 VSS .3 VDD V

RESET VSS .15 VDD V

Low-Level Output Voltage

VOL TXCAN — 0.6 V IOL = +6.0 mA, VDD = 4.5V

RXnBF Pins — 0.6 V IOL = +8.5 mA, VDD = 4.5V

SO, CLKOUT — 0.6 V IOL = +2.1 mA, VDD = 4.5V

INT — 0.6 V IOL = +1.6 mA, VDD = 4.5V

High-Level Output Voltage V

VOH TXCAN, RXnBF Pins VDD – 0.7 — V IOH = -3.0 mA, VDD = 4.5V

SO, CLKOUT VDD – 0.5 — V IOH = -400 µA, VDD = 4.5V

INT VDD – 0.7 — V IOH = -1.0 mA, VDD = 4.5V

Input Leakage Current

ILI All I/O except OSC1 and -1 +1 µA CS = RESET = VDD,

TXnRTS pins VIN = VSS to VDD

OSC1 Pin -5 +5 µA

CINT Internal Capacitance — 7 pF TAMB = 25°C, fC = 1.0 MHz,

(All Inputs and Outputs) VDD = 0V (Note 1)

IDD Operating Current — 10 mA VDD = 5.5V, FOSC = 25 MHz,

FCLK = 1 MHz, SO = Open

IDDS Standby Current (Sleep mode) — 5 µA CS, TXnRTS = VDD, Inputs tied to
VDD or VSS, -40°C TO +85°C

— 8 µA CS, TXnRTS = VDD, Inputs tied to

VDD or VSS, -40°C TO +125°C

Note 1: This parameter is periodically sampled and not 100% tested.

DS21801G-page 72  2003-2012 Microchip Technology Inc.

 MCP2515
TABLE 13-2: OSCILLATOR TIMING CHARACTERISTICS
Industrial (I): TAMB = -40°C to +85°C VDD = 2.7V to 5.5V
Oscillator Timing Characteristics(Note)
Extended (E): TAMB = -40°C to +125°C VDD = 4.5V to 5.5V

Param. Sym Characteristic Min Max Units Conditions

No.

FOSC Clock-In Frequency 1 40 MHz 4.5V to 5.5V

1 25 MHz 2.7V to 5.5V

TOSC Clock-In Period 25 1000 ns 4.5V to 5.5V

40 1000 ns 2.7V to 5.5V

TDUTY Duty Cycle 0.45 0.55 — TOSH/(TOSH + TOSL)

(External Clock Input)

Note: This parameter is periodically sampled and not 100% tested.

TABLE 13-3: CAN INTERFACE AC CHARACTERISTICS

Industrial (I): TAMB = -40°C to +85°C VDD = 2.7V to 5.5V
CAN Interface AC Characteristics
Extended (E): TAMB = -40°C to +125°C VDD = 4.5V to 5.5V

Param. Sym Characteristic Min Max Units Conditions

No.

TWF Wake-up Noise Filter 100 — ns

TABLE 13-4: RESET AC CHARACTERISTICS

Industrial (I): TAMB = -40°C to +85°C VDD = 2.7V to 5.5V
RESET AC Characteristics
Extended (E): TAMB = -40°C to +125°C VDD = 4.5V to 5.5V

Param. Sym Characteristic Min Max Units Conditions

No.

trl RESET Pin Low Time 2 — µs

 2003-2012 Microchip Technology Inc. DS21801G-page 73

MCP2515
TABLE 13-5: CLKOUT PIN AC CHARACTERISTICS
Industrial (I): TAMB = -40°C to +85°C VDD = 2.7V to 5.5V
CLKOUT Pin AC/DC Characteristics
Extended (E): TAMB = -40°C to +125°C VDD = 4.5V to 5.5V
Param. Sym Characteristic Min Max Units Conditions
No.

thCLKOUT CLKOUT Pin High Time 15 — ns TOSC = 40 ns (Note 1)

tlCLKOUT CLKOUT Pin Low Time 15 — ns TOSC = 40 ns (Note 1)
trCLKOUT CLKOUT Pin Rise Time — 5 ns Measured from 0.3 VDD to 0.7 VDD
(Note 1)
tfCLKOUT CLKOUT Pin Fall Time — 5 ns Measured from 0.7 VDD to 0.3 VDD
(Note 1)
tdCLKOUT CLOCKOUT Propagation Delay — 100 ns Note 1
15 thSOF Start-Of-Frame High Time — 2 TOSC ns Note 1
16 tdSOF Start-Of-Frame Propagation — 2 TOSC + ns Measured from CAN bit sample
Delay 0.5 TQ point. Device is a receiver.
CNF1.BRP<5:0> = 0 (Note 2)
Note 1: All CLKOUT mode functionality and output frequency is tested at device frequency limits, however, CLKOUT prescaler
is set to divide by one. This parameter is periodically sampled and not 100% tested.
2: Design guidance only, not tested.

FIGURE 13-1: START-OF-FRAME PIN AC CHARACTERISTICS

16
RXCAN sample point

15

DS21801G-page 74  2003-2012 Microchip Technology Inc.

 MCP2515
TABLE 13-6: SPI INTERFACE AC CHARACTERISTICS
Industrial (I): TAMB = -40°C to +85°C VDD = 2.7V to 5.5V
SPI Interface AC Characteristics
Extended (E): TAMB = -40°C to +125°C VDD = 4.5V to 5.5V

Param.
Sym Characteristic Min Max Units Conditions
No.

FCLK Clock Frequency — 10 MHz

1 TCSS CS Setup Time 50 — ns

2 TCSH CS Hold Time 50 — ns

3 TCSD CS Disable Time 50 — ns

4 TSU Data Setup Time 10 — ns

5 THD Data Hold Time 10 — ns

6 TR CLK Rise Time — 2 µs Note 1

7 TF CLK Fall Time — 2 µs Note 1

8 THI Clock High Time 45 — ns

9 TLO Clock Low Time 45 — ns

ns

10 TCLD Clock Delay Time 50 — ns

11 TCLE Clock Enable Time 50 — ns

12 TV Output Valid from Clock Low — 45 ns

13 THO Output Hold Time 0 — ns

14 TDIS Output Disable Time — 100 ns

Note 1: This parameter is not 100% tested.

 2003-2012 Microchip Technology Inc. DS21801G-page 75

MCP2515
NOTES:

DS21801G-page 76  2003-2012 Microchip Technology Inc.

 MCP2515
14.0 PACKAGING INFORMATION

14.1 Package Marking Information

18-Lead PDIP (300 mil) Example:

XXXXXXXXXXXXXXXXX e3
MCP2515-I/P^^
XXXXXXXXXXXXXXXXX
YYWWNNN 0434256

18-Lead SOIC (300 mil) Example:

XXXXXXXXXXXX MCP2515
XXXXXXXXXXXX e3
E/SO^^
XXXXXXXXXXXX
YYWWNNN 1035256

20-Lead TSSOP (4.4 mm) Example:

XXXXXXXX MCP2515
XXXXXNNN IST e^3 256
YYWW 1035

20-Lead QFN (4x4) Example:

XXXXX 2515
XXXXXX e3
E/ML^^
YWWNNN 035256

Legend: XX...X Customer-specific information

Y Year code (last digit of calendar year)
YY Year code (last 2 digits of calendar year)
WW Week code (week of January 1 is week ‘01’)
NNN Alphanumeric traceability code
e3 Pb-free JEDEC designator for Matte Tin (Sn)
* This package is Pb-free. The Pb-free JEDEC designator ( e3 )
can be found on the outer packaging for this package.

Note: In the event the full Microchip part number cannot be marked on one line, it will
be carried over to the next line, thus limiting the number of available
characters for customer-specific information.

 2003-2012 Microchip Technology Inc. DS21801G-page 77

MCP2515

/HDG3ODVWLF'XDO,Q/LQH3±PLO%RG\>3',3@
1RWH )RUWKHPRVWFXUUHQWSDFNDJHGUDZLQJVSOHDVHVHHWKH0LFURFKLS3DFNDJLQJ6SHFLILFDWLRQORFDWHGDW
KWWSZZZPLFURFKLSFRPSDFNDJLQJ


NOTE 1
E1

1 2 3
D

A A2

L c
A1
b1

b e eB

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 †6LJQLILFDQW&KDUDFWHULVWLF
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 'LPHQVLRQLQJDQGWROHUDQFLQJSHU$60(<0
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DS21801G-page 78  2003-2012 Microchip Technology Inc.

 MCP2515

Note: For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging

 2003-2012 Microchip Technology Inc. DS21801G-page 79

MCP2515

Note: For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging

DS21801G-page 80  2003-2012 Microchip Technology Inc.

 MCP2515

Note: For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging

 2003-2012 Microchip Technology Inc. DS21801G-page 81

MCP2515

/HDG3ODVWLF7KLQ6KULQN6PDOO2XWOLQH67±PP%RG\>76623@
1RWH )RUWKHPRVWFXUUHQWSDFNDJHGUDZLQJVSOHDVHVHHWKH0LFURFKLS3DFNDJLQJ6SHFLILFDWLRQORFDWHGDW
KWWSZZZPLFURFKLSFRPSDFNDJLQJ

E1

NOTE 1

1 2

b e

c φ
A A2

A1 L1 L

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 3LQYLVXDOLQGH[IHDWXUHPD\YDU\EXWPXVWEHORFDWHGZLWKLQWKHKDWFKHGDUHD
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 'LPHQVLRQLQJDQGWROHUDQFLQJSHU$60(<0
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5() 5HIHUHQFH'LPHQVLRQXVXDOO\ZLWKRXWWROHUDQFHIRULQIRUPDWLRQSXUSRVHVRQO\
0LFURFKLS 7HFKQRORJ\ 'UDZLQJ &%

DS21801G-page 82  2003-2012 Microchip Technology Inc.

 MCP2515

Note: For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging

 2003-2012 Microchip Technology Inc. DS21801G-page 83

MCP2515

/HDG3ODVWLF4XDG)ODW1R/HDG3DFNDJH0/±[[PP%RG\>4)1@
1RWH )RUWKHPRVWFXUUHQWSDFNDJHGUDZLQJVSOHDVHVHHWKH0LFURFKLS3DFNDJLQJ6SHFLILFDWLRQORFDWHGDW
KWWSZZZPLFURFKLSFRPSDFNDJLQJ

D D2
EXPOSED
PAD

e
E2

E
2 2 b

1 1
K

N N
NOTE 1 L
TOP VIEW BOTTOM VIEW

A3 A1

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'LPHQVLRQ/LPLWV 0,1 120 0$;
1XPEHURI3LQV 1 
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([SRVHG3DG:LGWK (   
2YHUDOO/HQJWK ' %6&
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1RWHV
 3LQYLVXDOLQGH[IHDWXUHPD\YDU\EXWPXVWEHORFDWHGZLWKLQWKHKDWFKHGDUHD
 3DFNDJHLVVDZVLQJXODWHG
 'LPHQVLRQLQJDQGWROHUDQFLQJSHU$60(<0
%6& %DVLF'LPHQVLRQ7KHRUHWLFDOO\H[DFWYDOXHVKRZQZLWKRXWWROHUDQFHV
5() 5HIHUHQFH'LPHQVLRQXVXDOO\ZLWKRXWWROHUDQFHIRULQIRUPDWLRQSXUSRVHVRQO\
0LFURFKLS 7HFKQRORJ\ 'UDZLQJ &%

DS21801G-page 84  2003-2012 Microchip Technology Inc.

 MCP2515

1RWH )RUWKHPRVWFXUUHQWSDFNDJHGUDZLQJVSOHDVHVHHWKH0LFURFKLS3DFNDJLQJ6SHFLILFDWLRQORFDWHGDW
KWWSZZZPLFURFKLSFRPSDFNDJLQJ

 2003-2012 Microchip Technology Inc. DS21801G-page 85

MCP2515
NOTES:

DS21801G-page 86  2003-2012 Microchip Technology Inc.

 MCP2515
APPENDIX A: REVISION HISTORY Revision A (May 2003)
• Original Release of this Document.
Revision G (August 2012)
The following is the list of modifications:
1. Updated content in Register 4-1, Register 4-12,
Register 4-13, Register 4-16, Register 4-17.

Revision F (October 2010)

The following is the list of modifications:
1. Added 20-lead QFN package (4x4) and related
information.
2. Updated Table 1-1.
3. Updated the Product Identification System
section.

Revision E (November 2007)

• Removed preliminary watermark.
• Updated templates.
• Updated register information.
• Updated package outline drawings.

Revision D (April 2005)

• Added Table 8-1 and Table 8-2 in Section 8.0
“Oscillator”. Added note box following tables.
• Changed address bits in column heading in
Table 11-1, Section 11.0 “Register Map”.
• Modified Section 14.0 “Packaging Information”
to reflect pb free device markings.
• Appendix A Revision History: Rearranged order of
importance.

Revision C (November 2004)

• Section 9.0 “RESET” added.
• Heading 12.1: added notebox.
Heading 12.6: Changed verbiage within
paragraph in Section 12.0 “SPI Interface”.
• Added Appendix A: Revision History.

Revision B (September 2003)

• Front page bullet: Standby current (typical) (Sleep
mode) changed from 10 µA to 1 µA.
• Added notebox for maximum frequency on
CLKOUT in Section 8.2 “CLKOUT Pin”.
• Section 12.0 “SPI Interface”, Table 12-1:
- Changed supply voltage minimum to 2.7V.
- Internal Capacitance: Changed VDD condition
to 0V.
- Standby Current (Sleep mode): Split
specification into -40°C to +85°C and
-40°C to +125°C.

 2003-2012 Microchip Technology Inc. DS21801G-page 87

MCP2515
NOTES:

DS21801G-page 88  2003-2012 Microchip Technology Inc.

 MCP2515
PRODUCT IDENTIFICATION SYSTEM
To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office.

PART NO. – X /XX Examples:

a) MCP2515-E/P: Extended Temperature,
Device Temperature Package 18LD PDIP package.
Range
b) MCP2515-I/P: Industrial Temperature,
18LD PDIP package.
Device: MCP2515: CAN Controller with SPI Interface c) MCP2515-E/SO: Extended Temperature,
MCP2515T: CAN Controller with SPI Interface 18LD SOIC package.
(Tape and Reel) d) MCP2515-I/SO: Industrial Temperature,
18LD SOIC package.
e) MCP2515T-I/SO: Tape and Reel,
Temperature I = -40C to +85C (Industrial) Industrial Temperature,
Range: E = -40C to +125C (Extended) 18LD SOIC package.
f) MCP2515-I/ST: Industrial Temperature,
Package: P = Plastic DIP (300 mil Body), 18-Lead 20LD TSSOP package.
SO = Plastic SOIC (300 mil Body), 18-Lead g) MCP2515T-I/ST: Tape and Reel,
ST = TSSOP, (4.4 mm Body), 20-Lead Industrial Temperature,
ML = Plastic QFN, (4x4 mm Body), 20-Lead
20LD TSSOP package.
h) MCP2515-E/ML: Extended Temperature,
20LD QFN package.
i) MCP2515T-E/ML Tape and Reel,
Extended Temperature,
20LD QFN package.
j) MCP2515-I/ML: Industrial Temperature,
20LD QFN package.
k) MCP2515T-I/ML Tape and Reel,
Industrial Temperature,
20LD QFN package.

 2003-2012 Microchip Technology Inc. DS21801G-page 89

MCP2515
NOTES:

DS21801G-page 90  2003-2012 Microchip Technology Inc.

Note the following details of the code protection feature on Microchip devices:
• Microchip products meet the specification contained in their particular Microchip Data Sheet.

• Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the
intended manner and under normal conditions.

• There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our
knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data
Sheets. Most likely, the person doing so is engaged in theft of intellectual property.

• Microchip is willing to work with the customer who is concerned about the integrity of their code.

• Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not
mean that we are guaranteeing the product as “unbreakable.”

Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our
products. Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts
allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act.

Information contained in this publication regarding device Trademarks

applications and the like is provided only for your convenience
The Microchip name and logo, the Microchip logo, dsPIC,
and may be superseded by updates. It is your responsibility to
KEELOQ, KEELOQ logo, MPLAB, PIC, PICmicro, PICSTART,
ensure that your application meets with your specifications.
PIC32 logo, rfPIC and UNI/O are registered trademarks of
MICROCHIP MAKES NO REPRESENTATIONS OR
Microchip Technology Incorporated in the U.S.A. and other
WARRANTIES OF ANY KIND WHETHER EXPRESS OR countries.
IMPLIED, WRITTEN OR ORAL, STATUTORY OR
OTHERWISE, RELATED TO THE INFORMATION, FilterLab, Hampshire, HI-TECH C, Linear Active Thermistor,
INCLUDING BUT NOT LIMITED TO ITS CONDITION, MXDEV, MXLAB, SEEVAL and The Embedded Control
QUALITY, PERFORMANCE, MERCHANTABILITY OR Solutions Company are registered trademarks of Microchip
FITNESS FOR PURPOSE. Microchip disclaims all liability Technology Incorporated in the U.S.A.
arising from this information and its use. Use of Microchip Analog-for-the-Digital Age, Application Maestro, BodyCom,
devices in life support and/or safety applications is entirely at chipKIT, chipKIT logo, CodeGuard, dsPICDEM,
the buyer’s risk, and the buyer agrees to defend, indemnify and dsPICDEM.net, dsPICworks, dsSPEAK, ECAN,
hold harmless Microchip from any and all damages, claims, ECONOMONITOR, FanSense, HI-TIDE, In-Circuit Serial
suits, or expenses resulting from such use. No licenses are Programming, ICSP, Mindi, MiWi, MPASM, MPLAB Certified
conveyed, implicitly or otherwise, under any Microchip logo, MPLIB, MPLINK, mTouch, Omniscient Code
intellectual property rights. Generation, PICC, PICC-18, PICDEM, PICDEM.net, PICkit,
PICtail, REAL ICE, rfLAB, Select Mode, Total Endurance,
TSHARC, UniWinDriver, WiperLock and ZENA are
trademarks of Microchip Technology Incorporated in the
U.S.A. and other countries.
SQTP is a service mark of Microchip Technology Incorporated
in the U.S.A.
All other trademarks mentioned herein are property of their
respective companies.
© 2003-2012, Microchip Technology Incorporated, Printed in
the U.S.A., All Rights Reserved.
Printed on recycled paper.

ISBN: 978-1-62076-504-3

QUALITY MANAGEMENT SYSTEM Microchip received ISO/TS-16949:2009 certification for its worldwide
headquarters, design and wafer fabrication facilities in Chandler and
CERTIFIED BY DNV Tempe, Arizona; Gresham, Oregon and design centers in California
and India. The Company’s quality system processes and procedures

== ISO/TS 16949 ==
are for its PIC® MCUs and dsPIC® DSCs, KEELOQ® code hopping
devices, Serial EEPROMs, microperipherals, nonvolatile memory and
analog products. In addition, Microchip’s quality system for the design
and manufacture of development systems is ISO 9001:2000 certified.

 2003-2012 Microchip Technology Inc. DS21801G-page 91

 Worldwide Sales and Service
AMERICAS ASIA/PACIFIC ASIA/PACIFIC EUROPE
Corporate Office Asia Pacific Office India - Bangalore Austria - Wels
2355 West Chandler Blvd. Suites 3707-14, 37th Floor Tel: 91-80-3090-4444 Tel: 43-7242-2244-39
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Fax: 480-792-7277 Hong Kong Tel: 45-4450-2828
Tel: 91-11-4160-8631
Technical Support: Tel: 852-2401-1200 Fax: 45-4485-2829
Fax: 91-11-4160-8632
http://www.microchip.com/ Fax: 852-2401-3431
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support
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Web Address:
Tel: 61-2-9868-6733 Fax: 91-20-2566-1513 Fax: 33-1-69-30-90-79
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Fax: 905-673-6509 Fax: 86-592-2388130
China - Zhuhai
Tel: 86-756-3210040
11/29/11
Fax: 86-756-3210049

DS21801G-page 92  2012 Microchip Technology Inc.