SPRUJ53B April 2024 – September 2024 TMS320F28P550SJ , TMS320F28P559SJ-Q1
The Tx handler is used to handle the Tx requests. The Tx handler controls the transfer of transmit messages from the dedicated Tx buffers, the Tx FIFO, and the Tx Queue to the CAN Core, the Tx Event FIFO, and the Put and Get Index operations. The MCAN module supports up to 32 Tx buffers. These Tx buffers can be configured as dedicated Tx buffers, Tx FIFO, or Tx Queue and as combination of dedicated Tx buffers/Tx FIFO or dedicated Tx buffers/Tx Queue. For each Tx Buffer element Classical CAN or CAN FD transmission mode can be configured. Section 28.5.16.3 describes the Tx Buffer Element. Table 28-9 shows the possible configurations for message transmission.
MCAN_CCCR Register | Tx Buffer Element | Frame Transmission | |||
---|---|---|---|---|---|
BRSE | FDOE | FDF | BRS | ||
ignored | 0 | ignored | ignored | Classic CAN | |
0 | 1 | 0 | ignored | Classic CAN | |
0 | 1 | 1 | ignored | CAN FD without bit rate switching | |
1 | 1 | 0 | ignored | Classic CAN | |
1 | 1 | 1 | 0 | CAN FD without bit rate switching | |
1 | 1 | 1 | 1 | CAN FD with bit rate switching |
When the Tx Buffer Request Pending (MCAN_TXBRP) register is updated, or when a transmission has been started the Tx Handler starts scanning to check for the highest priority pending Tx request. The Tx Buffer with the lowest Message ID has highest priority.