Reading these bits will return the contents of the Receive Data register. The
register must be read only when the Receive Complete Interrupt Flag bit in the
Interrupt Flag Status and Clear register (INTFLAG.RXC) is set. The status bits in
STATUS must be read before reading the DATA value in order to get any corresponding
error.
Writing these bits will write the Transmit Data register. This register must be
written only when the Data Register Empty Interrupt Flag bit in the Interrupt Flag
Status and Clear register (INTFLAG.DRE) is set.
Reads and writes are 32-bit or CTLB.CHSIZE based on the CTRLC.DATA32B
setting.