The Client data register I/O location (DATA.DATA) provides
access to the Host transmit and receive data buffers. Reading valid data or writing
data to be transmitted can be successfully done only when SCL is held low by the
Client (STATUS.CLKHOLD is set). An exception occurs when reading the last data byte
after the stop condition has been received.
Accessing DATA.DATA auto-triggers
I2C bus operations. The operation performed depends on the state of
CTRLB.ACKACT, CTRLB.SMEN and the type of access (read/write).
When CTRLC.DATA32B=1, read and write transactions from/to the DATA register are 32
bit in size. Otherwise, reads and writes are 8 bit.
