I've released version 1.7.1 of my Arduino board package (See https://github.com/femtoio/ArduinoCore-atsamd21e18a )

It includes working example sketches for the FemtoBeacon coins and dongle. You can give each coin sensor a unique address, and stream it back to a FemtoBeacon dongle.

Install the board package, select "ATSAMR21E18A (Native USB)" and upload the corresponding sketch for coins and an RF dongle (remember to give each coin a unique address greater than 1, as 1 is the RF dongle's address)