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Hardware Hacking for JavaScript Developers

Tomomi Imura
September 16, 2015

Hardware Hacking for JavaScript Developers

In the era of Internet of Things, connecting things to the mobile devices and web is becoming ubiquitous. You can control room light using your mobile phone. You can monitor your heart rate and weight on browser. Front-end developers like you already have skills to prototype software ideas, so why not prototyping the Internet of Everything?

- Arduino
- Raspberry Pi
- Johnny-Five JS robotics framework

Tomomi Imura

September 16, 2015

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    Hacking for JavaScript Devs https://flic.kr/p/8tuc1u by randomliteraturecouncil CC-BY 2.0
  2. @girlie_mac I am a: • Front-End Engineer • N00b Hardware

    Hacker • Sr. Developer Evangelist at PubNub
  3. @girlie_mac Withings: Smart Body Analyzer GE Link Cinder Sensing Cooker

    Nest: Learning Thermostat Whistle: Connected pet collar Amazon Dash Button
  4. @girlie_mac Programming Tessel in Node.js var tessel = require('tessel'); var

    camera = require('camera-vc0706').use(tessel.port['A']); camera.on('ready', function() { camera.takePicture(function(err, image) { if (err) { console.log(err); } else { var name = 'pic-' + Date.now() + '.jpg'; process.sendfile(name, image); camera.disable(); } }); }); the port the camera module is plugged in ready event callback
  5. @girlie_mac Raspberry Pi USB TO POWER SOURCE TO MONITOR TO

  6. @girlie_mac Ohm’s Law & Resistors R = V - V

    s f I source voltage (V) forward voltage (V) (LED voltage drop) current thru the LED (A) resistance (Ω)
  7. @girlie_mac Ohm’s Law & Resistors R = 3.3 - 1.9

    0.02 source voltage (V) forward voltage (V) (LED voltage drop) current thru the LED (A) resistance (Ω) = 70Ω
  8. @girlie_mac Programming Pi with Node.js Download & install Node.js with

    node-arm: $ wget http://node-arm.herokuapp. com/node_latest_armhf.deb $ sudo dpkg -i node_latest_armhf.deb
  9. @girlie_mac Johnny-Five • JavaScript robotics framework • Works with Arduino-compatible

    Boards • IO plugins for more platform supports • http://johnny-five.io/ Woot!
  10. @girlie_mac Blinking LED var five = require('johnny-five'); var raspi =

    require('raspi-io'); var board = new five.Board({io: new raspi()}); board.on('ready', function() { var led = new five.Led(7); // Create an instance led.blink(500); // "blink" in 500ms on-off phase periods }); Pin 7 (GPIO-4) Plugin for RPI (Default w/o plugins works for all Arduino)
  11. @girlie_mac Sending Data from browser var pubnub = PUBNUB.init({ subscribe_key:

    'sub-c-...', publish_key: 'pub-c-...' }); function lightOn() { pubnub.publish({ channel: 'remote-led', message: {light: true}, callback: function(m) {console.log(m);}, error: function(err) {console.log(err);} }); } document.querySelector('button') .addEventListener('click', lightOn); button click
  12. @girlie_mac Receiving Data to MCU var pubnub = require('pubnub').init({ subscribe_key:

    'sub-c-...', publish_key: 'pub-c-...' }); pubnub.subscribe({ channel: channel, callback: function(m) { if(m.blink) { // blink LED } } }); led.pulse();
  13. @girlie_mac Sending Data from browser redInput.addEventListener('change', function(e){ publishUpdate({color: 'red', brightness:

    +this.value}); }, false); function publishUpdate(data) { pubnub.publish({ channel: 'hue', message: data }); } Send the red value to PubNub to tell the MCU to reflect the change! the value has changed! Publish the new value!
  14. @girlie_mac Receiving Data to LED pubnub.subscribe({ channel: 'hue', callback: function(m)

    { if(led) { r = (m.color === 'red') ? m.brightness : r; g = (m.color === 'green') ? m.brightness : g; b = (m.color === 'blue') ? m.brightness : b; led.color({red: r, blue: b, green: g}); } } }); to the GPIO pins that connect to LED anodes
  15. @girlie_mac KittyCam in Node.js 1. Detect motion (Johnny-Five IR.Motion obj)

    2. Take photos (Raspistill, command line tool) 3. Cat facial detection (KittyDar) 4. Store the photos in Cloudinary 5. Publish the data to PubNub 6. Stream on web (subscribe the data from PubNub)
  16. @girlie_mac PIR Sensor > Run Camera board.on('ready', function() { //

    Create a new `motion` hardware instance. var motion = new five.Motion(7); //a PIR is wired on pin 7 (GPIO 4) // 'calibrated' occurs once at the beginning of a session motion.on('calibrated', function() {console.log('calibrated');}); motion.on('motionstart', function() { // Motion detected // Run raspistill command to take a photo with the camera module var filename = 'photo/image_'+i+'.jpg'; var args = ['-w', '320', '-h', '240', '-o', filename, '-t', '1']; var spawn = child_process.spawn('raspistill', args); ... motion detected! Take a photo!
  17. @girlie_mac Processing Photo ... spawn.on('exit', function(code) { if((/jpg$/).test(filename)) { var

    imgPath = __dirname + '/' + filename; // Child process: read the file and detect cats with KittyDar var args = [imgPath]; var fork = child_process.fork(__dirname+'/detectCatsFromPhoto.js'); fork.send(args); // the child process is completed fork.on('message', function(base64) { if(base64) { // Send to cloud storage } }); ... var kittydar = require ('kittydar'); a cat detected!