Endless fun with Arduino and Eventmachine

After seven years of working as a java developer, Bodo fall in love with ruby and moved to cologne to work as a full time ruby developer. He started tinkering with hardware as a teenager with his C-64, his dad created the robots and he wrote the software that made them move. Besides coding Bodo loves diving, traveling and biking.

In his talk he will show how to connect an arduino with ruby using eventmachine. He will also show potential use cases and projects that can be created using this technique. Most of the projects can be finished on one weekend.

Transcript

1. Hi!
   

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2. Bodo Tasche
   @bitboxer
   

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4. Endless fun with Arduino and
   Eventmachine
   

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5. Eventmachine
   

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6. Eventmachine
   !
   !
   !
   !
   !
   

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7. Arduino
   

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8. Arduino
   ?
   ?
   ? ?!
   

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9. Source: Wikipedia
   

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10. Two Parts
    

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11. 1. Hardware
    

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13. Arduino Uno
    

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14. Microcontroller ATmega328
    Operating Voltage 5V
    Input Voltage (recommended) 7-12V
    Input Voltage (limits) 6-20V
    Digital I/O Pins 14
    Analog Input Pins 6
    DC Current per I/O Pin 40 mA
    DC Current for 3.3V Pin 50 mA
    Flash Memory 32 KB
    SRAM 2 KB
    EEPROM 1 KB
    Clock Speed 16 MHz
    

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15. 2. Software
    

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16. View Slide

17. http://arduino.cc
    

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18. Christopher Pike, is
    this you?
    

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19. View Slide

20. const int PIN_LED = 13;!
    !
    void setup() {!
    pinMode(PIN_LED, OUTPUT);!
    }!
    !
    void loop() {!
    digitalWrite(PIN_LED, HIGH);!
    delay(500);!
    digitalWrite(PIN_LED, LOW);!
    delay(500);!
    }
    

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21. Have you brought any fruits or
    vegetables to the mars?
    !
    Two weeks.
    

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22. const int BAUD_RATE = 9600;!
    !
    void setup() {!
    Serial.begin(BAUD_RATE);!
    }!
    !
    void loop() {!
    Serial.println(“Hello, world!”);!
    delay(1000);!
    }
    

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23. Well, well, Private Joker, I don't
    believe I heard you correctly!
    

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24. http://arduino.cc/en/Tutorial/SwitchCase2
    

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25. void setup() {!
    Serial.begin(9600);!
    for (int thisPin = 2; thisPin < 7; thisPin++) {!
    pinMode(thisPin, OUTPUT);!
    }!
    }
    

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26. void loop() {!
    if (Serial.available() > 0) {!
    int inByte = Serial.read();!
    switch (inByte) {!
    case 'a': digitalWrite(2, HIGH);!
    break;!
    case 'b': digitalWrite(3, HIGH);!
    break;!
    case 'c': digitalWrite(4, HIGH);!
    break;!
    case 'd': digitalWrite(5, HIGH);!
    break;!
    case 'e': digitalWrite(6, HIGH);!
    break;!
    default:!
    for (int thisPin = 2; thisPin < 7; thisPin++) {!
    digitalWrite(thisPin, LOW);!
    }!
    }!
    }!
    }
    

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27. Eventmachine
    +
    Arduino
    

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28. It‘s all about the volume!
    

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29. Source: Wikipedia
    

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30. const int POT_PIN = 2;!
    !
    int val;!
    !
    void setup() {!
    Serial.begin(9600);!
    }!
    !
    void loop() {!
    int newVal = map(analogRead(POT_PIN), 0, 1023, 7, 0);!
    !
    if (val != newVal) {!
    val = newVal;!
    Serial.println(val);!
    }!
    !
    }
    

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31. Source: Wikipedia
    

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32. require 'serialport'!
    !
    sp = SerialPort.new('/dev/tty.your-usb-device', 9600, 8, 1, 0)!
    !
    loop do!
    line = sp.gets!
    if line!
    puts "New volume : #{line}"!
    `osascript -e "set volume #{line}"`!
    end!
    end!
    !
    sp.close!
    

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33. Talk to the hand
    

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34. require 'rubygems'!
    require 'serialport'!
    require 'eventmachine'!
    !
    $sp = SerialPort.new('/dev/tty.your-usb-device', 9600, 8, 1, 0)!
    !
    class DataBuffer < EM::Protocols::LineAndTextProtocol!
    !
    def initialize!
    puts "hello stranger..."!
    end!
    !
    def receive_data(data)!
    EventMachine::defer do!
    $sp.puts data.strip!
    send_data($sp.gets)!
    end !
    end!
    !
    end!
    !
    EventMachine::run do!
    EventMachine::start_server "127.0.0.1", 8081, DataBuffer!
    end!
    !
    sp.close!
    

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35. EventMachine::defer
    

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36. Don’t write a deferred operation
    that will block forever [...] We might
    put in a timer to detect this
    

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37. $eventmachine_library = :pure_ruby # need to force pure ruby!
    require 'eventmachine'!
    gem_original_require 'serialport'!
    require 'smsrelay/gsmpdu'!
    !
    module EventMachine!
    class EvmaSerialPort < StreamObject!
    def self.open(dev, baud, databits, stopbits, parity)!
    io = SerialPort.new(dev, baud, databits, stopbits, parity)!
    return(EvmaSerialPort.new(io))!
    end!
    !
    def initialize(io)!
    super!
    end!
    !
    ##!
    # Monkeypatched version of EventMachine::StreamObject#eventable_read so!
    # that EOFErrors from the SerialPort object (which the ruby-serialport!
    # library uses to signal the fact that there is no more data available!
    # for reading) do not cause the connection to unbind.!
    def eventable_read!
    @last_activity = Reactor.instance.current_loop_time!
    begin!
    if io.respond_to?(:read_nonblock)!
    10.times {!
    data = io.read_nonblock(4096)!
    EventMachine::event_callback uuid, ConnectionData, data!
    }!
    else!
    data = io.sysread(4096)!
    EventMachine::event_callback uuid, ConnectionData, data!
    end!
    rescue Errno::EAGAIN, Errno::EWOULDBLOCK, EOFError!
    # no-op!
    rescue Errno::ECONNRESET, Errno::ECONNREFUSED!
    @close_scheduled = true!
    EventMachine::event_callback uuid, ConnectionUnbound, nil!
    end!
    end!
    end!
    !
    class << self!
    def connect_serial(dev, baud, databits, stopbits, parity)!
    EvmaSerialPort.open(dev, baud, databits, stopbits, parity).uuid!
    end!
    end!
    !
    def EventMachine::open_serial(dev, baud, databits, stopbits, parity,!
    handler=nil)!
    klass = if (handler and handler.is_a?(Class))!
    handler!
    else!
    Class.new( Connection ) {handler and include handler}!
    end!
    s = connect_serial(dev, baud, databits, stopbits, parity)!
    c = klass.new s!
    @conns[s] = c!
    block_given? and yield c!
    c!
    end!
    !
    class Connection!
    # This seems to be necessary with EventMachine 0.12.x!
    def associate_callback_target(sig)!
    return(nil)!
    end!
    end!
    end!
    https://github.com/eventmachine/eventmachine/wiki/Code-Snippets
    

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38. If you build it...
    

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39. http://blog.last.fm/2008/08/01/quality-control
    Last.fm
    

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40. http://urbanhonking.com/ideasfordozens/2010/05/19/the_github_stoplight/
    github
    

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41. by-nc-nd by seanb.murphy http://www.flickr.com/photos/greenstorm/2425378283
    

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42. Weather station
    

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43. Infrared Sender/Receiver
    

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44. Improve your
    „green thumb“
    

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45. CAN-bus
    

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46. Gong-o-bot
    

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47. Gong-o-bot
    

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49. fritzing.org/projects/
    

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50. fritzing.org/shop/starter-kit/
    

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51. Find a hackerspace!
    

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52. delicious.com/bitboxer/arduino
    

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53. Don‘t be evil
    Source: Wikipedia
    

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54. Be good!
    Source: Wikipedia
    

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55. Thank you!
    

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