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
Acceptance Mask
RXM0
Acceptance Filter
c
A
c
c
e
p
t
RXF3
c
TXB0
TXB1
TXB2
e
p
t
Acceptance Filter
RXF0
Acceptance Filter
RXF4
Acceptance Filter
RXF1
Acceptance Filter
RXF5
R
X
B
1
R
X
B
0
M
A
B
Identifier
Identifier
Message
Queue
Control
Transmit Byte Sequencer
Data Field
Data Field
PROTOCOL
ENGINE
Receive
Error
Counter
REC
TEC
Transmit
Error
Counter
ErrPas
BusOff
Transmit<7:0>
Shift<14:0>
Receive<7:0>
{Transmit<5:0>, Receive<8:0>}
Comparator
Protocol
Finite
SOF
State
CRC<14:0>
Machine
Bit
Timing
Logic
Transmit
Logic
Clock
Generator
TX
RX
Configuration
Registers
© 2005 Microchip Technology Inc.
Preliminary
DS21801D-page 5
MICROCHIP [ MICROCHIP ]
