35.6.7.9.6 Pointer Operation when DATA Transmission

As in normal operation, data transmission is initiated by writing the data to be sent into the TX FIFO through the DATA register. Then, the data in TX FIFO will be moved to the TX Shift register when the Shift register is empty and ready to send a new frame. After the TX Shift register is loaded with data, the data frame will be transmitted.

As long as data is present in TX FIFO, (FIFOSPACE.TXSPACE ≠ 0), new data will be automatically loaded in the TX Shift register when the previous data transmission is completed. All FIFO pointers increment to their maximum value, dictated by the CTRLC.DATA32B bit, and then rolls over to ‘0’.

Depending on the TX FIFO Threshold settings (CTRLC.TXTRHOLD), Interrupt Flag Status and Clear register (INTFLAG.DRE) indicates that the register is empty and ready for new data.