38.5.7 Transmit Priority

The transmit priority of the FIFOs and TXQ needs to be configured using the TXPRIx bits (CxFIFOCONy[20:16] and CxTXQCON[20:16]).

Before transmitting a message, the priorities of the TXQ and the TX FIFOs queued for transmission are compared. The FIFO/TXQ with the highest priority will be transmitted first. For example, if transmit FIFO 1 has a higher priority setting than FIFO 3, all messages in FIFO 1 will be transmitted first. If multiple FIFOs have the same priority, the FIFO with the highest index is transmitted. For example, if FIFO 1 and FIFO 3 have the same priority setting, all messages in FIFO 3 will be transmitted first. If the TXQ and one or more FIFOs have the same priority, all messages in the TXQ will be transmitted first.

The transmit priority will be recalculated after every successful transmission of a single message.