57.7.12 16-bit Data Protocol Support
When configuring 0xC in FLEX_US_MR.USART_MODE, the transmitter sends a 16-bit data frame and the receiver expects an 8-bit data frame. The number of stop bits is defined in the field NBSTOP. The transmitter and/or receiver must operate in asynchronous mode (FLEX_US_MR.SYNC must be cleared).
When configuring 0xD in FLEX_US_MR.USART_MODE, the transmitter sends an 8-bit frame whereas the receiver expects a 16-bit frame.
The FIFO mode must be enabled by setting FLEX_US_CR.FIFOEN to ‘1’.
A 16-bit frame starts as soon as two 8-bit characters are written in FLEX_US_THR (assuming 0xC is written in the field USART_MODE).