SAM C21 Xplained Pro has two power sources as described in Power Sources. Figure 1 shows a block diagram of the power supply circuitry. The kit can be powered from the EDBG USB and an external 5.0V source. The kit will automatically select which source to draw power from.
The EDBG controls an on-board power switch to the ATSAMC21J18A, the on-board peripherals, and extension connectors. When the kit is powered up, the EDBG reads the ID chip information from all connected Xplained Pro extension boards and checks that they are compatible with the voltage selected by the power selection jumper. If the selected voltage is within the connected extensions ranges the switch will open. If not, the EDBG power LED will blink rapidly and the switch will stay closed resulting in no power provided to the ATSAMC21J18A, on-board peripherals, and connectors.
