@User, @User: Because we do not (yet) have a crystal oscillator circuit design, the clock input is a single-pin CMOS input. If we use the same one as we have had on our test boards, it would be a DSC6001 (10MHz) (Microchip MEMS oscillator) or eqivalent. Any CMOS clock would be fine for driving the system, and there will be a jumper that grounds the EN pin on the oscillator chip and allows you to connect an external clock signal through a header pin.

Right, thank you!

Unfortunately Microchip has discontinued DSC6001 recently after using it in striVe and Caravel boards. You may want to use the DSC6003 instead.