25.4.1 Receiver Data Register Low Byte

This register contains the eight LSbs of the data received by the USART receiver. The USART receiver is double-buffered, and this register always represents the data for the oldest received frame. If data for only one frame is present in the receive buffer, this register contains that data.

The buffer shifts out the data either when RXDATAL or RXDATAH is read, depending on the configuration. The register that does not lead cause the data to be shifted must be read first to allow both bytes to be read before shifting occurs.

When the Character Size (CHSIZE) bit field in the Control C (USARTn.CTRLC) register is configured to 9-bit (low byte first), reading RXDATAH shifts the receive buffer; otherwise, reading RXDATAL shifts the buffer.