From CampJS VIII, Melbourne 4 - 7 August 2017 This session will show you how to take your robotics and IoT dreams and make them reality through the magic of JavaScript, including: selecting hardware and developing circuits, overview of some of the different options for developing programs to read from sensors and control actuators for robotics and IoT projects using JS, connecting your device and getting it talking with other devices and services

1. Do you want to build a
robot?
Anna Gerber

2. Robot Design
A robot is an autonomous system that senses
and responds to, or acts upon the physical world

3. Sensors
(Inputs e.g. ultrasonic sensor)
Control
(Microcontroller or
Single-Board-Computer)
Actuators
(Outputs e.g. motors)
PowerChassis

4. JS Robotics
• http://johnny-five.io/
• https://www.espruino.com/
• https://tessel.io/
• https://docs.particle.io/reference/javascript/
• https://cylonjs.com/
• http://jerryscript.net/
• http://mujs.com/
• http://duktape.org/

5. Selecting hardware
• Johnny-Five supports Arduino, Raspberry Pi, Tessel, Particle,
BeagleBone, and more

6. Johnny-Five
• Open Source JavaScript Robotics
Framework for Node.js
https://github.com/rwaldron/johnny-five
• Communicates with microcontrollers like
Arduino using the Firmata protocol
• Runs on-board devices that can run Node.js
e.g. Raspberry Pi, BeagleBone Black, via I/O
Plugins

7. Set up Raspberry Pi Zero W (headless)
• Install Raspbian:
• https://www.raspberrypi.org/documentation/installation/installing-
images/README.md
• Create a file named wpa_supplicant.conf on the microSD card:
network={
ssid="campjs"
psk="morecoffee"
}
• Add a file named ssh (contents don’t matter) on the root of the
microSD card to enable SSH on boot

8. Connect to the Raspberry Pi
• Rpi uses mDNS so connect to the Pi over SSH:
• ssh pi@raspberrypi.local
• Default password is raspberry
• (Make sure you change this)
• Raspbian comes with node.js installed but if you are using something
else, install node
• Then use npm to install the dependencies:
• npm install serialport
• npm install johnny-five raspi-io

9. Raspberry Pi GPIO
• Solder some headers on to the Raspberry
Pi Zero W for the GPIO pins
• Peripheral components (e.g. sensors,
actuators) attach via these pins
• 3.3V logic
• In Johnny-Five the pins are named
"P[header]-[pin]” e.g. P1-7

10. Breadboard
• Use to prototype circuits without soldering by
plugging in components and jumper wires
• Numbered rows are connected
• Some have power rails along the sides

11. Attach an LED using a Breadboard

12. Writing Johnny-Five programs
1. Create a JavaScript file (e.g. blink.js) on the Pi
2. Edit it using a text editor
3. Require the johnny-five library and raspi-io libraries into and set up the
board object using the IO/Plugin
const raspi = require('raspi-io');
const five = require('johnny-five');
const board = new five.Board({
io: new raspi()
});

13. Ready event
• When the board is ready for our code to start interacting with it and
the attached sensors and actuators, it will trigger a ready event
board.on('ready', () => {
// code for sensors, actuators goes here
});

14. LED
• Create an Led instance
// attach LED on pin 7
const led = new five.Led('P1-7');
// call strobe function to blink once per second
led.strobe(1000);
• We can change the parameter to the strobe function to change the speed: This
input value is provided in milliseconds

15. LED blink program
const raspi = require('raspi-io');
const five = require('johnny-five');
const board = new five.Board({
io: new raspi()
});
board.on('ready', () => {
// LED attached to RPi pin 7 (GPIO4)
const led = new five.Led('P1-7');
led.strobe(500);
});

16. Inputs - Sensors
• Environmental conditions (e.g. temperature, humidity)
• Magnetic (e.g. hall effect sensor)
• Light (e.g. photo resistor)
• Sound (e.g. microphone, piezo)
• Movement / position (e.g. accelerometer, tilt switch)
• User Input (e.g. button)

17. Inputs
PHOTO RESISTOR
Resistance changes depending on the
amount of ambient light
TILT SWITCH
Detect orientation
PUSH BUTTON
Also known as momentary switch
PIEZO ELEMENT
Detect vibrations or knocks
TEMPERATURE SENSOR
Read the ambient temperature

18. Outputs
• Light & Displays (e.g. LED, LCD screen)
• Sound (e.g. Piezo buzzer)
• Movement (e.g. Servo, DC Motor, Solenoid)
• Relays

19. Outputs
PIEZO ELEMENT
A pulse of current will cause it to click. A stream of
pulses will cause it to emit a tone.
RGB LED
We are using Common Cathode RGB LEDs. The
longer lead is the common lead which connects to
ground. The three other leads are for Red, Green
and Blue signal
9G HOBBY SERVO
A box containing a motor with gears to make it
positionable from 0 to 180 degrees.

20. Digital vs Analog
• Digital
• discrete values (0 or 1)
• Examples: tilt sensor, push button
• Analog
• continuous values
• typically values for analog sensors are constrained within a range e.g. 0 – 255,
0 – 1023
• Example: photo resistor
• Some components support both digital and analog

21. REPL
• Read, Eval, Print Loop
• A console for real-time interaction with the code
• Expose our variables to the REPL to enable interactive control:
board.on('ready', () => {
// LED attached to RPi pin 7 (GPIO4)
const myLed = new five.Led('P1-7');
myLed.strobe(500);
board.repl.inject({
led: myLed
});
});

22. Controlling the LED via the REPL
• At the REPL prompt type commands followed by enter
• Try:
• stop,
• on,
• off,
• toggle,
• strobe
e.g:
>> led.stop()

23. Buttons
const button = new five.Button("P1-11");
const led = new five.Led("P1-7");
button.on("down", (value) => {
led.on();
});
button.on(”up", (value) => {
led.off();
});
http://johnny-five.io/api/button/

24. Servos
const myServo = new five.Servo("P1-35");
board.repl.inject({
servo: myServo
});
myServo.sweep();
board.wait(5000, () => {
myServo.stop();
myServo.center();
});

25. PWM
• Pulse Width Modulation
• Produce analog output via digital pins
• Instead of on or off, a square wave is sent to simulate voltages
between 0V (off) and 5V (on)
• Used to control motors, fade LEDs etc

26. Piezo
const piezo = new five.Piezo("P1-32");
let val = 0;
board.loop(200, function() {
if (val ^= 1) {
// Play note a4 for 1/5 second
piezo.frequency(five.Piezo.Notes["a4"], 200);
}
});

27. Motors
const leftMotor = new five.Motor({
pins: {pwm: "P1-35", dir: "P1-13"},
invertPWM: true
});
const rightMotor = new five.Motor({
pins: {pwm: "P1-32", dir: "P1-15"},
invertPWM: true
});
leftMotor.forward(150);
rightMotor.forward(150);
See Johnny-Five motor API
http://johnny-five.io/api/motor/

28. Node-RED

29. • Anna’s blog: http://crufti.com
• http://johnny-five.io/
• Node-ARDX (examples for Arduino): http://node-ardx.org
Read more