The SAM C21 Xplained Pro has a 3-pin header labeled VCC_SEL on the board. This header can be used to select between 3.3V and 5.0V as the supply voltage for the ATSAMC21J18A, peripherals, and extension headers by placing a jumper on pin 1-2 or pin 2-3. Selecting 5.0V will supply the kit directly from the USB or an external 5.0V source. Selecting 3.3V will supply the kit from an on-board regulator.
| VCC_SEL header pin | Function |
|---|---|
| 1 | VCC_P5V0 |
| 2 | VCC_TARGET |
| 3 | VCC_P3V3 |