SWRU626 December 2025 CC3501E , CC3551E
Debug messages are stored into Rx Buffers. For debug handling three consecutive Rx buffers (e.g. #61, #62, #63) have to be used for storage of debug messages A, B, and C. The format is the same as for an Rx Buffer or an Rx FIFO element (see M_CAN User’s Manual section 2.4.2).
Advantage: Fixed start address for the DMA transfers (relative to RXBC.RBSA), no additional configuration required.
For filtering of debug messages Standard / Extended Filter Elements with SFEC / EFEC = “111” have to be set up. Messages matching these filter elements are stored into the Rx Buffers addressed by SFID2 / EFID2[5:0].
After message C has been stored, the DMA request output m_can_dma_req is activated and the three messages can be read from the Message RAM under DMA control. The RAM words holding the debug messages will not be changed by the DCAN while m_can_dma_req is activated. The behaviour is similar to that of an Rx Buffers with its New Data flag set.
After the DMA has completed the DMA unit sets m_can_dma_ack. This resets m_can_dma_req. Now the DCAN is prepared to receive the next set of debug messages.