25.5.1 I/O Lines
In order to use the SERCOM’s I/O lines, the I/O pins must be configured using the IO Pin Controller (PORT).
When the SERCOM is configured for SPI operation, the SERCOM controls the direction and value of the I/O pins according to the table below. Both PORT control bits PINCFGn.PULLEN and PINCFGn.DRVSTR are still effective. If the receiver is disabled, the data input pin can be used for other purposes. In Host mode, the Client select line (SS) is controlled by software.
| Pin | Host SPI | Client SPI |
|---|---|---|
| MOSI | Output | Input |
| MISO | Input | Output |
| SCK | Output | Input |
| SS | User defined output enable | Input |
The combined configuration of PORT, the Data In Pinout and the Data Out Pinout bit groups in the Control A register (CTRLA.DIPO and CTRLA.DOPO) define the physical position of the SPI signals in the table above.