38.5.4 Requesting Transmission of Message in Transmit FIFO

After a message is loaded into a transmit FIFO, the message is ready for transmission. The application initiates the transmission of all messages in a FIFO by setting the TXREQ bit (CxFIFOCONy[9]) or by setting the corresponding bit in the C1TXREQ register. When all messages are transmitted, TXREQ gets cleared. The application can request transmission of multiple FIFOs and the TXQ simultaneously. The FIFO or TXQ with the highest priority will start transmitting first. Messages in a FIFO will be transmitted First-In First-Out.

Messages can be loaded into a FIFO while the FIFO is transmitting messages. Since TXREQ is cleared by the FIFO automatically after the FIFO empties, UINC and TXREQ of the CxFIFOCONy register must be set at the same time after appending a message. This ensures that all messages in the FIFO are transmitted, including the appended messages.