4.2.1 Crystals
The SAM L21 Xplained Pro kit contains one mounted 32.768kHz crystal and a footprint for higher frequency crystals that can be used as clock sources for the SAM L21. The crystals have cut-straps next to them that can be used to measure the oscillator safety factor. This is done by cutting the strap and adding a resistor across the strap. Information about oscillator allowance and safety factor can be found in application note AVR41001, information about clock calibration and compensation can be found in application note AT03155.
The footprint for the external crystal is based on the Fox FQ5032B series.
Info: Note that PA14 and PA15 are shared with USB VBUS detect
and EXT3 pin 5. To disconnect PA14 and PA15 from all functionality except XTAL cut J300
and J302.
| SAM L21 pin | Function | Shared functionality |
|---|---|---|
| PA00 | XIN32 | - |
| PA01 | XOUT32 | - |