21.4.8 Serial Data Transmission

When the TPI physical layer is ready to send a new frame it initiates data transmission by loading the shift register with the data to be transmitted. When the shift register has been loaded with new data, the transmitter shifts one complete frame out on the TPIDATA line at the transfer rate given by TPICLK.

If a collision is detected during transmission, the output driver is disabled. The TPI access layer enters the error state and the TPI physical layer is put into receive mode, waiting for a BREAK character.