SPRUIU1C July 2020 – February 2024 DRA821U , DRA821U-Q1
The UART is capable of full 9-bit operation when configured so in UART_MDR4[6] MODE9 bit. The full 9-bit data can only be written and read through the UART_ETHR / UART_ERHR registers. The data can be accessed either with a single or two accesses using appropriate OCP byte enables. In case two accesses are used, make sure to read/write the higher byte first, as reading/writing the lower one will advance the FIFO.
The UART_RHR / UART_ERHR and UART_THR / UART_ETHR registers point to the same location and either can be used as preferred, in regards to the lower 8 bits.