the time goes forward 5 minutes each week

Also, thanks for the test code @BartS23!

Thinking about that, I wonder whether something could be added to https://banglejs.com/apps/?id=widadjust to allow it to figure out the drift using GPS.

Even this code:

let lastTime = getTime();
function calcTimeDifference(fix) {
  if (!fix.time) return;
  var t = getTime();
  print(t-lastTime);
  lastTime = t;
}
console.log(process.env.VERSION);
Bangle.on("GPS", calcTimeDifference);
Bangle.setGPSPower(1);
NRF.setConnectionInterval(200); // low BLE speed = less GPS interference

Works surprisingly well - because we know the GPS sends data once a second, we just see how many seconds the Bangle thinks have passed. Obviously it'd be better averaging over more seconds though.

2v22:

1.00073289871
1.00045800209
1.00067186355
1.00073266029
1.00045800209
1.00067186355
1.00073289871
1.00045800209
1.00067162513
1.00076341629
1.00045800209

With the fix:

1.00009155273
1.00009155273
1.00009155273
1.00006103515
1.00006103515
1.00009155273
1.00006103515
1.00009155273
1.00006103515
1.00003051757
1.00009155273

So it's an order of magnitude better