There are up to four instances of the serial communication interface (SERCOM) peripheral.
A SERCOM can be configured to support a number of modes: I2C, SPI, and USART. When SERCOM is configured and enabled, all SERCOM resources will be dedicated to the selected mode.
The SERCOM serial engine consists of a transmitter and receiver, baud-rate generator and address matching functionality. It can use the internal generic clock or an external clock to operate in all sleep modes.