Configuration

The user can choose between two DMA modes by the DMAM bit in the LON Mode register

(FLEX_US_LONMR):

  • DMAM = 1: The LON frame data length (DATAL) is stored in the WRITE buffer and it is written by the DMA in the Transmit Holding register FLEX_US_THR (instead of the LON Data Length register FLEX_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 the LON Data Length Register (FLEX_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 8-72. DMAM = 1
Figure 8-73. DMAM = 0