PIC18F2480/2580/4480/4580
24.2.2
DEDICATED CAN TRANSMIT
BUFFER REGISTERS
This section describes the dedicated CAN Transmit
Buffer registers and their associated control registers.
REGISTER 24-5: TXBnCON: TRANSMIT BUFFER n CONTROL REGISTERS [0 ≤ n ≤ 2]
U-0
—
R-0
TXABT(1)
R-0
R-0
R/W-0
U-0
—
R/W-0
TXPRI1(3) TXPRI0(3)
R/W-0
Mode 0
TXLARB(1) TXERR(1) TXREQ(2)
R/C-0
TXBIF
R-0
TXABT(1)
R-0
R-0
R/W-0
U-0
—
R/W-0
TXPRI1(3) TXPRI0(3)
bit 0
R/W-0
Mode 1,2
TXLARB(1) TXERR(1) TXREQ(2)
bit 7
Legend:
C = Clearable bit
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
bit 7
Mode 0:
Unimplemented: Read as ‘0’
Mode 1, 2:
TXBIF: Transmit Buffer Interrupt Flag bit
1= Transmit buffer has completed transmission of message and may be reloaded
0= Transmit buffer has not completed transmission of a message
bit 6
bit 5
bit 4
bit 3
TXABT: Transmission Aborted Status bit(1)
1= Message was aborted
0= Message was not aborted
TXLARB: Transmission Lost Arbitration Status bit(1)
1= Message lost arbitration while being sent
0= Message did not lose arbitration while being sent
TXERR: Transmission Error Detected Status bit(1)
1= A bus error occurred while the message was being sent
0= A bus error did not occur while the message was being sent
TXREQ: Transmit Request Status bit(2)
1= Requests sending a message. Clears the TXABT, TXLARB and TXERR bits.
0= Automatically cleared when the message is successfully sent
bit 2
Unimplemented: Read as ‘0’
TXPRI<1:0>: Transmit Priority bits(3)
bit 1-0
11= Priority Level 3 (highest priority)
10= Priority Level 2
01= Priority Level 1
00= Priority Level 0 (lowest priority)
Note 1: This bit is automatically cleared when TXREQ is set.
2: While TXREQ is set, Transmit Buffer registers remain read-only. Clearing this bit in software while the bit is
set will request a message abort.
3: These bits define the order in which transmit buffers will be transferred. They do not alter the CAN
message identifier.
DS39637D-page 288
© 2009 Microchip Technology Inc.
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