11.2.47 CAN FIFO Status Register x (x = 1 to 8)
- The FIFOCI[4:0] bits provide a zero-indexed value to the message in the FIFO. If the FIFO is four messages deep (FSIZE[4:0] = 3), FIFOCIx will take on a value from 0 to 3, depending on the state of the FIFO.
- These bits are updated when a message completes (or aborts) or when the FIFO is reset.
- This bit is reset on any read of this register or when the TXQ is reset. The bits are cleared when TXREQ is set or by using an SPI write.
Legend: HS = Hardware Settable bit; C = Clearable bit
| Name: | C1FIFOSTAx |
| Offset: | 0x620, 0x62C, 0x638, 0x644, 0x650, 0x65C, 0x668, 0x674 |
| Bit | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | |
| FIFOCI[4:0] | |||||||||
| Access | R | R | R | R | R | ||||
| Reset | 0 | 0 | 0 | 0 | 0 | ||||
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |
| TXABT | TXLARB | TXERR | TXATIF | RXOVIF | TFERFFIF | TFHRFHIF | TFNRFNIF | ||
| Access | R | R | R | HS/C | HS/C | R | R | R | |
| Reset | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
Bits 12:8 – FIFOCI[4:0] FIFO Message Index bits(1)
1
(FIFO configured as a transmit buffer):A read of this register will return an index to the message that the FIFO will next attempt to transmit.
TXEN = 0 (FIFO configured as a receive
buffer):
A read of this register will return an index to the message that the FIFO will use to save the next message.
Bit 7 – TXABT Message Aborted Status bit(3)
| Value | Description |
|---|---|
1 |
Message was aborted. |
0 |
Message completed successfully. |
Bit 6 – TXLARB Message Lost Arbitration Status bit(2)
| Value | Description |
|---|---|
1 |
Message lost arbitration while being sent. |
0 |
Message did not lose arbitration while being sent. |
Bit 5 – TXERR Error Detected During Transmission bit(2)
| Value | Description |
|---|---|
1 |
A bus error occurred while the message was being sent. |
0 |
A bus error did not occur while the message was being sent. |
Bit 4 – TXATIF Transmit Attempts Exhausted Interrupt Pending bit
TXEN = 0 (FIFO configured as a receive buffer):
Unused, read as ‘0’.
TXEN = 1 (FIFO configured as a transmit
buffer):
| Value | Description |
|---|---|
1 |
Interrupt is pending. |
0 |
Interrupt is not pending. |
Bit 3 – RXOVIF Receive FIFO Overflow Interrupt Flag bit
TXEN = 1 (FIFO configured as a transmit
buffer):
Unused, read as ‘0’.
TXEN = 0 (FIFO configured as a receive buffer):
| Value | Description |
|---|---|
1 |
Overflow event has occurred. |
0 |
No overflow event has occurred. |
Bit 2 – TFERFFIF Transmit/Receive FIFO Empty/Full Interrupt Flag bit
TXEN = 1 (FIFO configured as a transmit FIFO):
| Value | Description |
|---|---|
1 | FIFO is empty. |
0 | FIFO is not empty, at least one message is queued to be transmitted. |
TXEN = 0 (FIFO configured as a receive FIFO):
Receive FIFO Full Interrupt Flag.
| Value | Description |
|---|---|
1 | FIFO is full. |
0 | FIFO is not full. |
Bit 1 – TFHRFHIF Transmit/Receive FIFO Half Empty/Half Full Interrupt Flag bit
TXEN = 1 (FIFO configured as a transmit
FIFO):
Transmit FIFO Half Empty Interrupt Flag.
| Value | Description |
|---|---|
1 | FIFO is ≤ half full. |
0 | FIFO is > half full. |
TXEN = 0 (FIFO configured as a receive FIFO):
Receive FIFO Half Full Interrupt Flag.
| Value | Description |
|---|---|
1 | FIFO is ≥ half full. |
0 | FIFO is < half full. |
Bit 0 – TFNRFNIF Transmit/Receive FIFO Not Full/Not Empty Interrupt Flag bit
TXEN = 1 (FIFO configured as a transmit
FIFO):
Transmit FIFO Not Full Interrupt Flag.
| Value | Description |
|---|---|
1 | FIFO is not full. |
0 | FIFO is full. |
TXEN = 0 (FIFO configured as a receive FIFO):
Receive FIFO Not Empty Interrupt Flag.
| Value | Description |
|---|---|
1 | FIFO is not empty, has at least 1 message. |
0 | FIFO is empty. |