4.1.2 VDDIO Header

The SAM L21 Xplained Pro has a 2-pin header connecting the power supply from the VCC_MCU net to VCC_IO net through a jumper. This header can be used to measure the current to the I/O block of the SAM L21 device by removing the jumper and connect an ammeter. SAM L21 has the possibility to run the I/O block at a lower voltage level than the MCU is running and thus support interfacing devices that require lower operating voltages. The header can then be used to power the VCC_IO pin at a different voltage level by removing the jumper and connecting a power supply with the desired voltage. Refer to the datasheet of the device for valid operating voltages.