The DMA mode is configured in USLONMR.DMAM:
- DMAM = 1: The LON frame data length (DATAL) is stored in the WRITE buffer and it is written by the DMA in US_THR (instead of the LON Data Length register US_LONDL).
- DMAM = 0: The LON frame data length (DATAL) is not stored in the WRITE buffer and it must be written by the user in US_LONDL.
In both DMA modes L2HDR is considered as a data and its value must be stored in the WRITE buffer as the first data to write.
Figure 1. DMAM = 1
Figure 2. DMAM = 0
