Just to add: If you're using strong magnets near your Puck the you can magnetise it slightly which will knock off your calibration value (and you'll have to take the 4 readings again).
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
Thanks - this looks great.
Just to add: If you're using strong magnets near your Puck the you can magnetise it slightly which will knock off your calibration value (and you'll have to take the 4 readings again).