30.5.1 I/O Lines
Using the USART’s I/O lines requires the I/O pins to be configured using the System Configuration registers or PPS registers.
When the SERCOM is used in USART mode, the SERCOM controls the direction and value of the I/O pins according to the table below. If the receiver or transmitter is disabled, these pins can be used for other purposes.
| Pin | Pin Configuration |
|---|---|
| TxD | Output |
| RxD | Input |
| XCK | Output or input |
The combined configuration of PORT and the Transmit Data Pinout and Receive Data Pinout bit fields in the Control A register (CTRLA.TXPO and CTRLA.RXPO, respectively) will define the physical position of the USART signals in the above table.