57.7.11.6 FIFO Single Data Access

When FIFO is enabled and a byte access is performed in FLEX_US_THR (5-bit to 8-bit data size), a single data is written in FIFO. The similar behavior applies for FLEX_US_RHR.

If FLEX_US_MR.MODE9 is set (9-bit data), or if FLEX_US_MR.USART_MODE is configured to operate in LON mode, LIN Host mode or LIN Client mode, or if FLEX_US_MR.MAN is set, any type of access to FLEX_US_THR/RHR writes/reads a single data.

See USART Receive Holding Register (FLEX_US_RHR) and USART Transmit Holding Register (FLEX_US_THR).

However, for some configurations it is possible to write/read multiple data each time FLEX_US_THR/FLEX_US_RHR is accessed. See FIFO Multiple Data Access.