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!
2. Bodo Tasche
   @bitboxer
4. Endless fun with Arduino and Eventmachine
5. Eventmachine
6. Eventmachine ! ! ! ! !
7. Arduino
8. Arduino ? ? ? ?!
9. Source: Wikipedia
10. Two Parts
11. 1. Hardware
13. Arduino Uno
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
15. 2. Software
17. http://arduino.cc
18. Christopher Pike, is
    this you?
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);! }
21. Have you brought any fruits or vegetables to the mars?
    ! Two weeks.
22. const int BAUD_RATE = 9600;! ! void setup() {! Serial.begin(BAUD_RATE);! }! ! void loop() {! Serial.println(“Hello, world!”);! delay(1000);! }
23. Well, well, Private Joker, I don't believe I heard you correctly!
24. http://arduino.cc/en/Tutorial/SwitchCase2
25. void setup() {! Serial.begin(9600);! for (int thisPin = 2; thisPin < 7; thisPin++) {! pinMode(thisPin, OUTPUT);! }! }
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);! }! }! }! }
27. Eventmachine
    +
    Arduino
28. It‘s all about the volume!
29. Source: Wikipedia
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);! }! ! }
31. Source: Wikipedia
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!
33. Talk to the hand
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!
35. EventMachine::defer
36. Don’t write a deferred operation that will block forever [...] We might put in a timer to detect this
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
38. If you build it...
39. http://blog.last.fm/2008/08/01/quality-control Last.fm
40. http://urbanhonking.com/ideasfordozens/2010/05/19/the_github_stoplight/ github
41. by-nc-nd by seanb.murphy http://www.flickr.com/photos/greenstorm/2425378283
42. Weather station
43. Infrared Sender/Receiver
44. Improve your
    „green thumb“
45. CAN-bus
46. Gong-o-bot
47. Gong-o-bot
49. fritzing.org/projects/
50. fritzing.org/shop/starter-kit/
51. Find a hackerspace!
52. delicious.com/bitboxer/arduino
53. Don‘t be evil Source: Wikipedia
54. Be good! Source: Wikipedia
55. Thank you!