SWCU195A December 2024 – May 2025 CC2744R7-Q1 , CC2745P10-Q1 , CC2745R10-Q1 , CC2745R7-Q1 , CC2755R10
The Tx Buffers section can be configured to hold dedicated Tx Buffers as well as a Tx FIFO / Tx Queue. In case that the Tx Buffers section is shared by dedicated Tx buffers and a Tx FIFO / Tx Queue, the dedicated Tx Buffers start at the beginning of the Tx Buffers section followed by the buffers assigned to the Tx FIFO or Tx Queue. The Tx Handler distinguishes between dedicated Tx Buffers and Tx FIFO / Tx Queue by evaluating the Tx Buffer configuration TXBC.TFQS and TXBC.NDTB. The element size can be configured for storage of CAN FD messages with up to 64 bytes data field via register TXESC.
|
Tx Buffer |
Bit |
Name |
Description |
|---|---|---|---|
|
T0 |
31 |
ESI |
Error State Indicator 0= ESI bit in CAN FD format depends only on error passive flag 1= ESI bit in CAN FD format transmitted recessive Note: The ESI bit of the transmit buffer is or’ed with the error passive flag to decide the value of the ESI bit in the transmitted FD frame. As required by the CAN FD protocol specification, an error active node may optionally transmit the ESI bit recessive, but an error passive node will always transmit the ESI bit recessive |
|
30 |
TXD |
Extended Identifier 0= 11-bit standard identifier 1= 29-bit extended identifier |
|
|
29 |
RTR |
Remote Transmission Request 0= Transmit data frame 1= Transmit remote frame Note: WhenRTR = 1, the M_CAN transmits a remote frame according to ISO 11898-1:2015, even if CCCR.FDOE enables the transmission in CAN FD format. |
|
|
28:0 |
ID[28:0] |
Identifier Standard or extended identifier depending on bit XTD. Astandard identifier has to be written to ID[28:18]. |
|
|
T1 |
31:24 |
MM[7:0] |
Message Marker Written by CPU during Tx Buffer configuration. Copied into Tx Event FIFO element for identification of Tx message status. |
|
23 |
EFC |
Event FIFO Control 0= Don’t store Tx events 1= Store Tx events |
|
|
21 |
FDF |
FD Format 0= Frame transmitted in Classic CAN format 1= Frame transmitted in CAN FD format |
|
|
20 |
BRS |
Bit Rat Switching 0= CAN FD frames transmitted without bit rate switching 1= CAN FD frames transmitted with bit rate switching Note: Bits ESI, FDF, and BRS are only evaluated when CAN FD operation is enabled CCCR.FDOE = 1’. Bit BRS is only evaluated when in addition CCCR.BRSE = ‘1’. |
|
|
19:16 |
DLC[3:0] |
Data Length Code 0-8= CAN + CAN FD: transmit frame has 0-8 data bytes 9-15= CAN: transmit frame has 8 data bytes 9-15= CAN FD: transmit frame has 12/16/20/24/32/48/64 data bytes |
|
|
T2 |
31:24 |
DB3[7:0] |
Data Byte 3 |
|
23:16 |
DB2[7:0] |
Data Byte 2 |
|
|
15:8 |
DB1[7:0] |
Data Byte 1 |
|
|
7:0 |
DB0[7:0] |
Data Byte 0 |
|
|
T3 |
31:24 |
DB7[7:0] |
Data Byte 7 |
|
23:16 |
DB6[7:0] |
Data Byte 6 |
|
|
15:8 |
DB5[7:0] |
Data Byte 5 |
|
|
7:0 |
DB4[7:0] |
Data Byte 4 |
|
|
... |
... |
... |
... |
|
Tn |
31:24 |
DBm[7:0] |
Data Byte m |
|
23:16 |
DBm-1[7:0] |
Data Byte m-1 |
|
|
15:8 |
DBm-2[7:0] |
Data Byte m-2 |
|
|
7:0 |
DBm-3[7:0] |
Data Byte m-3 |
Depending on the configuration of the element size (TXESC), between two and sixteen 32-bit words (Tn = 3 ..17) are used for storage of a CAN message’s data field.