Magnetometer sensitivity

@Gordon
Thanks, I missed this one
I tried something similar with start/stop movement detection with button, when pressed, Green led indicate it's on and then blink Red in case of movement. another push stop detection by blue blink
New position is saved like this moving and leaving puckjs to another place will stop detection until it's moved again. Seems to works, need to play with threeshold.
Here the code, I'll try your since your math detection looks better than mine ;)

var th = 10;
var x =0;
var y =0;
var z =0;
var accFirstRead = true;
var acc = false;

Puck.magOff();

function doJob(x,y,z) {
  var b = Puck.getBatteryPercentage();
  var t = E.getTemperature();
  var l = Puck.light()*100 ;
  console.log("Batt", b, "  Temp",t, "  Light",t );
  console.log("Diff X:",x, " Y:",y, "Z:",z);
}

setWatch(function() {
  if (acc) {
    Puck.magOff();
    acc = false;
    digitalPulse(LED3, 1, 100);
    console.log("Accel OFF");
  } else {
    accFirstRead = true;
    acc = true;
    //Puck.magOn(0.31);
    Puck.magOn();
    digitalPulse(LED2, 1, 100);
    console.log("Accel ON");
  }
}, BTN, {edge:"rising", debounce:50, repeat:true});

Puck.on('mag', function(xyz) {
  var diffx = xyz.x-x;
  var diffy = xyz.y-y;
  var diffz = xyz.z-z;
  x = xyz.x;
  y = xyz.y;
  z = xyz.z;
  //digitalPulse(LED3, 1, 5);
  //console.log(xyz);
  //doJob(xyz);

  if (accFirstRead) {
    accFirstRead = false;
    doJob(x,y,z);
  } else {
    if (Math.abs(diffx)>th || Math.abs(diffy)>th*2 || Math.abs(diffz)>th*2) {
      digitalPulse(LED1, 1, 250);
      doJob(diffx, diffy, diffz);
    } else {
      //console.log("Diff X:",diffx, " Y:",diffy, "Z:",diffz);
    }
  }
});