57.7.9.12.2 DMA and Collision Detection

As explained in section comm_type, depending on LON configuration the transmission may be terminated early upon collision notification which means that the DMA transfer may be stopped before its end.

In case of early end of transmission due to collision detection, the USART in LON mode acts as follows:

• Send the end of frame trigger.
• Hold down TXRDY, thus avoiding any additional DMA transfer.
• Set the LTXD, LCOL and LFET flags in FLEX_US_CSR.
• Wait for the application to reconfigure the DMA.
• Wait until the LCOL and LFET flags are cleared through the FLEX_US_CR.RSTSTA bit (it will release the TXRDY signal).