The SAM L21 Xplained Pro has a backup battery for use with the SAM L21 backup module. The battery can be connected to the device by placing a jumper over pin 1-2 on the 3-pin VBAT SELECT header.
By default the jumper is placed over pin 2-3 to select the board power supply. This configuration is selected to avoid draining the battery and can be used during development.
| VBAT SELECT pin | Function |
|---|---|
| 1 | Power from battery |
| 2 | PB03/VBAT pin on SAM L21 |
| 3 | Power from board supply |