• AVR ATmega microcontroller
• nice abstraction layer
• language: C/C++  (no worries!)
• many I/O
• USB plug 'n' play
• Price: $5 - $50

• 32Kb flash
• 2Kb RAM
• 8-bit, 20MHz CPU

const int ledPin = 13;

void setup() {                
  // initialize the digital pin as an output.
  pinMode(ledPin, OUTPUT);     
}

void loop() {
  digitalWrite(ledPin, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(1000);                  // wait for a second
  digitalWrite(ledPin, LOW);    // turn the LED off by making the voltage LOW
  delay(1000);                  // wait for a second
}

• measuring elapsed time (not so great)
• hardware timer interruptions

#include "SimpleTimer.h"

const int ledPin = 13;
SimpleTimer timer;

void setup() {
  timer.setInterval(1000, blink);
}

void loop() { 
  timer.run(); 
}

void blink() {
  digitalWrite(ledPin, digitalRead(ledPin) ^ 1); // toggle pin status
}

#include "TimerOne.h"

const int ledPin = 13;

void setup() {
  pinMode(ledPin, OUTPUT);
  digitalWrite(ledPin, LOW); // reset led state
  Timer1.initialize();
  Timer1.attachInterrupt(blink, 500 * 1000); // 500ms timeout
}

void loop() {}

void blink() {
  digitalWrite(ledPin, digitalRead(ledPin) ^ 1); // toggle pin status
}

• Serial port (built-in)
• Wi-Fi
• Bluetooth
• Ethernet

• two temperature sensors
• LED with regulated output
• communication through websockets
• present temperature on website
•  ...and control LED from website

• Sensor - DS18B20
• Protocol - One Wire

#include "TemperatureSensor.h"

TemperatureSensor sensor(2); // setup sensor on pin 2

void setup() {
  sensor.start();
  Serial.begin(9600);
}

void loop() {
  if (sensor.updateTemperature()) {
    Serial.println(sensor.getTemperature());
  }
}

 class ArduinoHandler
  serialport = require('serialport')

  constructor: (@device) ->
    @serialPort = new serialport.SerialPort @device,
      baudrate: 115200,
      dataBits: 8,
      parity: 'none',
      stopBits: 1,
      flowControl: false,
      parser: serialport.parsers.readline("\n")

  listen: (onData) ->
    @serialPort.on "open", => @serialPort.on('data', onData)

  send: (data) ->
    @serialPort.write("P#{data}")

@arduinoHandler = new ArduinoHandler('/dev/tty.usbmodem1421')

class Temperature
  history: []

  constructor: (@ioServer, @arduinoHandler) ->
    @arduinoHandler.listen(@update)
    @ioServer.onConnection(@pushHistory)

  update: (data) =>
    [device, temp] = data.split(':')
    @history.push
      device: parseInt(device)
      temp: temp
      date: new Date()
    @pushHistory()

  pushHistory: =>
    @ioServer.emit('change-temp', @history)

 class Pwm
  constructor: (@ioServer, @arduinoHandler) ->
    @ioServer.onConnection(@addEventListener)

  addEventListener: (socket) =>
    socket.on('change-pwm', @onChange)

  onChange: (pwm) =>
    @arduinoHandler.send(pwm)

 class App
  constructor: (@port, @device) ->
    @httpServer = new HttpServer(@port)
    @ioServer = new IoServer(@httpServer.getApp())
    @arduinoHandler = new ArduinoHandler(@device)

    @temperature = new Temperature(@ioServer, @arduinoHandler)
    @pwm = new Pwm(@ioServer, @arduinoHandler)

      function updatePwm() {
        val = $("#slider").slider('value');
        toPwm = Math.ceil(val * 2.55);
        socket.emit('change-pwm', toPwm)
      }

      $("#slider").slider({
        slide: updatePwm,
        change: updatePwm
      });

      function updateLatestTemperatures(history) {
        $('[data-role=temperature]').each(function(){
          deviceId = $(this).data('id');
          temp = _.chain(history)
                  .where({ device: deviceId }).last().value().temp
          $(this).html(temp)
        })
      }
      
      var socket = io.connect('http://192.168.5.10:3334');
      socket.on('change-temp', updateLatestTemperatures);

• Arduino on steroids
• ARM powered
• UNIX support - any high level language
• GPIO
• HDMI 1080p output
• Price? $50