WIP - Puck.js reading CSC (cycling speed cadence) BLE sensor to replace bike computer head unit with Puck.js or (later) Pixl.js

Hi Joost,

That looks really promising - and it's great that the Wahoo sensor uses a standard Bluetooth LE format for its data as well!

I think you just want to start notifications on the characteristic - check out http://www.espruino.com/Reference#l_Blue­toothRemoteGATTCharacteristic_startNotif­ications - there's some example code there that should do exactly what you want.

var gatt;
NRF.requestDevice({ filters: [{ namePrefix: 'Wahoo' }] }).then(function(device) {
  console.log(device);
  return device.gatt.connect();
}).then(function(g) {
  gatt = g;
  return gatt.getPrimaryService("1816");
}).then(function(service) {
  console.log("Service:" + service);
  return service.getCharacteristic("0x2A5B");
}).then(function(characteristic) {
  characteristic.on('characteristicvaluech­anged', function(event) {
    console.log("-> "+event.target.value);
  });
  return characteristic.startNotifications();
}).then(function() {
  console.log("Done!");
  // Then call gatt.disconnect(); if/when you want to disconnect
});

event.target.value should be a DataView so you should be able to pull out the relevant bits of the characteristic pretty easily.