SPRUIV7B May 2022 – September 2023 AM620-Q1 , AM623 , AM625 , AM625-Q1 , AM625SIP
Dedicated Tx Buffers are intended for message transmission under complete control of the Host CPU.
There are two options:
After the data section has been updated, a transmission is requested by an Add Request. This is done via the MCAN_TXBAR[x]ARn bit (where x = 0 - 31). The requested messages arbitrate internally with messages from an optional Tx FIFO or Tx Queue and externally with messages on the CAN bus, and are sent out according to their Message ID.
Table 12-260 shows Tx Buffer/Tx FIFO/Tx Queue Element Size. A Dedicated Tx Buffer allocates Element Size 32-bit words in the Message RAM. The start address of a dedicated Tx Buffer in the Message RAM is calculated by adding transmit buffer index from 0 to 31 (MCAN_TXFQS[20-16] TFQPI) × Element Size to the Tx Buffer Start Address MCAN_TXBC[15-2] TBSA field.
MCAN_TXESC[2-0] TBDS | Data Field [bytes] | Element Size [RAM words] | |||
---|---|---|---|---|---|
000 | 8 | 4 | |||
001 | 12 | 5 | |||
010 | 16 | 6 | |||
011 | 20 | 7 | |||
100 | 24 | 8 | |||
101 | 32 | 10 | |||
110 | 48 | 14 | |||
111 | 64 | 18 |