29.1.1.6 Transmitting 9-Bit Characters
The EUSART supports 9-bit character transmissions. When the TX9 bit of the TXxSTA register is set, the EUSART will shift nine bits out for each character transmitted. The TX9D bit of the TXxSTA register is the ninth, and Most Significant data bit. When transmitting 9-bit data, the TX9D data bit must be written before writing the eight Least Significant bits into the TXxREG. All nine bits of data will be transferred to the TSR shift register immediately after the TXxREG is written.
A special 9-bit Address mode is available for use with multiple receivers. See the 29.1.2.7 Address Detection section for more information on the Address mode.