Datasheet

© 2007 Microchip Technology Inc. DS21664D-page 5
MCP2502X/5X
2.0 CAN MODULE
The CAN module is a protocol controller that converts
between raw digital data and CAN message packets.
The main functional block of the CAN module is shown
in Figure 2-1 and consists of:
• CAN protocol engine
• Buffers, masks and filters
The module features include:
• Implementation of the CAN protocol
• Double-buffered receiver with two separate
receive buffers
• One full-acceptance mask (standard and
extended)
• Two full-acceptance filters (standard and
extended)
• One filter for each receive buffer
• Three prioritized transmit buffers for transmitting
predefined message types
• Automatic wake-up on bus traffic function
• Error management logic for transmit and receive
error states
• Low-power SLEEP mode
FIGURE 2-1: CAN MODULE
Acceptance Filter
RXF1
R
X
B
1
Identifier
Data Field Data Field
Identifier
M
A
B
Acceptance Mask
RXM
Acceptance Filter
RXF0
R
X
B
0
TXREQ
TXB2
ABTF MLOA TXERR MESSAGE
Message
Queue
Control
Transmit Byte Sequencer
TXREQ
TXB0
ABTF MLOA TXERR MESSAGE
CRC<14:0>
Comparator
Receive<7:0>Transmit<7:0>
Receive
Error
Transmit
Error
Protocol
REC
TEC
ErrPas
BusOf
f
Finite
State
Machine
Counter
Counter
Shift<14:0>
{Transmit<5:0>, Receive<8:0>}
Transmit
Logic
Bit
Timing
Logic
TXCAN/TXRXCAN RXCAN
Configuration
Registers
Clock
Generator
PROTOCOL
ENGINE
BUFFERS
TXREQ
TXB1
ABTF MLOA TXERR MESSAGE
A
c
c
e
p
t
A
c
c
e
p
t