This board has connections to mimic the Raspberry PI UART on the GPIO connector. It also has a RS232 level shifter and a RS422/485 transcievers that can get blue wired to any of the SERCOM pins. The RS232 and 422 chips drive pins on a separate connector, J11.

I blue-wired the RS232 level shifter to the SERCOM4 pins exposed on the Extra signals connector (J3) and the RS422 transciever to the SERCOM5 pins on J3. The Raspberry PI UART wiring goes to SERCOM0.

I have used the smaller version of this chip on previous projects, so I have a version of my own serial drivers that are pretty quick to configure for different setups on this chip. I modified the code to support SERCOM 0, 4, and 5 and tested it. They all work. I need to make up a short cable to mate with J11 and fan the signals out to various test equipment next. That will be a task for the morning.

The other two SERCOMs will be configured to support the I2C and SPI interfaces on the Raspberry PI GPIO connector. Getting code running to test those is next.