The user can choose between two DMAC modes by the PDCM bit in the US_LINMR:
- PDCM = 1: the LIN configuration is stored in the WRITE buffer and it is written by the DMAC in the Transmit Holding register US_THR (instead of the LIN Mode register US_LINMR). Because the DMAC transfer size is limited to a byte, the transfer is split into two accesses. During the first access the bits, NACT, PARDIS, CHKDIS, CHKTYP, DLM and FSDIS are written. During the second access the 8-bit DLC field is written.
- PDCM = 0: the LIN configuration is not stored in the WRITE buffer and it must be written by the user in US_LINMR.
The WRITE buffer also contains the Identifier and the DATA, if the USART sends the response (NACT = PUBLISH).
The READ buffer contains the DATA if the USART receives the response (NACT = SUBSCRIBE).
Figure 1. Master Node with DMAC (PDCM = 1)
Figure 2. Master Node with DMAC (PDCM = 0)
