SPRUIW9C October 2021 – March 2024 TMS320F280033 , TMS320F280034 , TMS320F280034-Q1 , TMS320F280036-Q1 , TMS320F280036C-Q1 , TMS320F280037 , TMS320F280037-Q1 , TMS320F280037C , TMS320F280037C-Q1 , TMS320F280038-Q1 , TMS320F280038C-Q1 , TMS320F280039 , TMS320F280039-Q1 , TMS320F280039C , TMS320F280039C-Q1
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 makes difference between dedicated Tx buffers and Tx FIFO/Tx Queue by way of the MCAN_TXBC.TFQS and MCAN_TXBC.NDTB fields. The element size can be configured for storage of CAN FD messages with up to 64 bytes data field by way of the MCAN_TXESC register.
Figure 29-21 shows the Tx Buffer element structure. Table 29-12 shows the Tx Buffer element field descriptions.
Word | Bits | Field Name | Description |
---|---|---|---|
T0 | 31 | ESI |
Error State Indicator
Note: The ESI bit of the transmit buffer is ORed with the error passive flag to decide the value of the ESI bit in the transmitted CAN FD frame. As required by the CAN FD protocol specification, an error active node can optionally transmit the ESI bit recessive, but an error passive node always transmits the ESI bit recessive. |
30 | XTD |
Extended Identifier
|
|
29 | RTR |
Remote Transmission Request
Note: When RTR = 1, the MCAN module transmits a remote frame according to ISO11898-1:2015, even if the MCAN_CCCR.FDOE bit enables the transmission in CAN FD format. |
|
28:0 | ID[28:0] |
Identifier Standard or extended identifier depending on XTD bit. A standard identifier has to be written to ID[28:18]. |
|
T1 | 31:24 | MM[7:0] |
Message Marker Written by Host CPU during Tx Buffer configuration. Copied into Tx Event FIFO element for identification of Tx message status (see also MM[7:0] field in Table 29-13). |
23 | EFC |
Event FIFO Control
|
|
22 | RES | Reserved | |
21 | FDF |
FD Format
|
|
20 | BRS |
Bit Rate Switch
Note: ESI, FDF, and BRS bits are only evaluated when CAN FD operation is enabled using the MCAN_CCCR.FDOE bit. BRS bit is only evaluated when MCAN_CCCR.BRSE = 1. |
|
19:16 | DLC[3:0] |
Data Length Code
|
|
15:0 | RES | Reserved | |
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 |