13.21.5.1 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 master mode, the slave select line (SS) is hardware controlled when the Master Slave Select Enable bit in the Control B register (CTRLB.MSSEN) is '1'.

Table 13-61. SPI Pin Configuration
Pin Master SPI Slave SPI
MOSI Output Input
MISO Input Output
SCK Output Input
SS Output (CTRLB.MSSEN=1) 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.