57.7.11.2 Sending Data with FIFO Enabled

When the Transmit FIFO is enabled, write access to FLEX_US_THR loads the Transmit FIFO.

The FIFO level is provided in FLEX_US_FLR.TXFL. If the FIFO can accept the number of data to be transmitted, there is no need to monitor FLEX_US_CSR.TXRDY and the data can be successively written in FLEX_US_THR.

If the FIFO cannot accept the data due to insufficient space, wait for the TXRDY flag to be set before writing the data in FLEX_US_THR.

When the space in the FIFO allows only a portion of the data to be written, the TXRDY flag must be monitored before writing the remaining data.