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 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.