This is a short summary of what I learned while playing around with my Bangle.js Watch.

I managed to

• add an application to the Bangle.js (with create-bangle-app)
• send accelerometer data over Bluetoot Low Energy
• discover & connect to BLE devices with Node.js
• read accelerometer data with Node.js (coming from the watch)

Bangle.js app

The simplest way to get started is to install create-bangle-app and read about Creating Bangle.js Apps

npm i -g create-bangle-app

Simply create a bangle app with create-bangle-app my-first-app

Put this code in the file index.js:

Bangle.on('accel',function(a) {
  var d = [Math.round(a.x*100), Math.round(a.y*100), Math.round(a.z*100)];
  Bluetooth.println(d.join(","));
})

This way, your Bangle will send it’s Accel values over BLE (Bluetooth Low Energy) continuously!

Node.js

On the Node.js side, I have set up some code to

• discover BLE devices (the Bangle.js specifically)
• Connect to it and read the Accel values broadcasted over Bluetooth

This is the idea

var noble = require('@abandonware/noble')

noble.startScanning()
noble.on('stateChange', function(state) {
  console.log('stateChange', state)
})
noble.on('discover', periphalDiscovered)

The function peripheralDiscovered connects to the Watch, reads the Accel values and moves the Computer mouse accordingly!