Address Mode Transmit

The UART transmitter is enabled for asynchronous address operation by configuring the following control bits:

Addresses are sent by writing to the UxP1L register. This transmits the written byte with the 9th bit set, which indicates that the byte is an address.

Data is sent by writing to the UxTXB register. This transmits the written byte with the 9th bit cleared, which indicates that the byte is data.

To send data to a particular device on the transmission bus, first transmit the address of the intended device. All subsequent data will be accepted only by that device until an address of another device is transmitted.

Writes to UxP1L take precedence over writes to UxTXB. When both the UxP1L and UxTXB registers are written while the TSR is busy, the next byte to be transmitted will be from UxP1L.

To ensure all data intended for one device are sent before the address is changed, wait until the TXMTIF bit is high before writing UxP1L with the new address.