36.5.3 Block Diagram

Figure 36-7. USART Block Diagram
Table 36-4. USART Pin Configuration
PinPin Configuration
TxDOutput
RxDInput
XCKOutput 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 pad assignments of the USART signals as shown in the table above.