Datasheet

© 2009 Microchip Technology Inc. DS39761C-page 297
PIC18F2682/2685/4682/4685
23.2.3.1 Programmable TX/RX and
Auto-RTR Buffers
The ECAN module contains 6 message buffers that can
be programmed as transmit or receive buffers. Any of
these buffers can also be programmed to automatically
handle RTR messages.
Note: These registers are not used in Mode 0.
REGISTER 23-22: BnCON: TX/RX BUFFER n CONTROL REGISTERS IN RECEIVE MODE
[0 ≤ n ≤ 5, TXnEN (BSEL0<n>) = 0]
(1)
R/W-0 R/W-0 R-0 R-0 R-0 R-0 R-0 R-0
RXFUL
(2)
RXM1 RXRTRRO FILHIT4 FILHIT3 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 RXFUL: Receive Full Status bit
(2)
1 = Receive buffer contains a received message
0 = Receive buffer is open to receive a new message
bit 6 RXM1: Receive Buffer Mode bit
1 = Receive all messages including partial and invalid (acceptance filters are ignored)
0 = Receive all valid messages as per acceptance filters
bit 5 RXRTRRO: Read-Only Remote Transmission Request for Received Message bit
1 = Received message is a remote transmission request
0 = Received message is not a remote transmission request
bit 4-0 FILHIT4:FILHIT0: Filter Hit bits
These bits indicate which acceptance filter enabled the last message reception into this buffer.
01111 = Acceptance Filter 15 (RXF15)
01110 = Acceptance Filter 14 (RXF14)
...
00001 = Acceptance Filter 1 (RXF1)
00000 = Acceptance Filter 0 (RXF0)
Note 1: These registers are available in Mode 1 and 2 only.
2: This bit is set by the CAN module upon receiving a message and must be cleared by software after the
buffer is read. As long as RXFUL is set, no new message will be loaded and the buffer will be considered
full.