Arduino Firmata

Firmata protocol implementation on Ruby.

View project onGitHub

arduino_firmata

Firmata is a protocol to controll Arduino from software on PC. You can embed Arduino code into Ruby application.
This library supports sharing an Arduino between multiple processes.

INSTALL

% gem install arduino_firmata

REQUIREMENTS

  • Ruby 1.8.7 or 1.9.2 or 1.9.3 or 2.0.0
  • testing with Arduino Diecimila, Duemillanove, UNO, Leonardo, Micro and Seeduino v2
  • Arduino Standard Firmata v2.2
    • Arduino IDE -> [File] -> [Examples] -> [Firmata] -> [StandardFirmata]

ArduinoFirmata Command

% arduino_firmata --help
% arduino_firmata --list
% arduino_firmata digital_write 13, true
% arduino_firmata analog_read 0
% arduino_firmata servo_write 9, 145

Sample Code

Setup

Connect

require "rubygems"
require "arduino_firmata"

arduino = ArduinoFirmata.connect  # use default arduino
arduino = ArduinoFirmata.connect "/dev/tty.usb-device-name"
arduino = ArduinoFirmata.connect "/dev/tty.usb-device-name", :bps => 57600
arduino = ArduinoFirmata.connect "/dev/tty.usb-device-name", :nonblock_io => true

Board Version

puts "firmata version #{arduino.version}"

Close

arduino.close

I/O

Digital Write

on board Yellow LED 
arduino.digital_write 13, true
arduino.digital_write 13, false

Digital Read

arduino.pin_mode 7, ArduinoFirmata::INPUT
puts arduino.digital_read 7  # => true/false

arduino.on :digital_read do |pin, status| # digital_read event
  if pin == 7
    puts "digital pin #{pin} changed : #{status}"
  end
end

Analog Write (PWM)

0.upto(255) do |i|
  arduino.analog_write 11, i  # <= 0 ~ 255
  sleep 0.01
end

Digital 11 PIN -> LED -> GND

Analog Read

puts arduino.analog_read 0  # => 0 ~ 1023

arduino.on :analog_read do |pin, value| # analog_read event
  if pin == 0
    puts "analog pin #{pin} changed : #{value}"
  end
end

GND & 5V -> CdS & 10kΩ -> Analog 0 PIN

Servo Motor

loop do
  angle = rand 180
  puts "servo angle #{angle}"
  arduino.servo_write 9, angle
  sleep 1
end

VCC, GND and Digital 9 PIN -> Servo Motor

Sysex

Send

arduino.sysex 0x01, [13, 5, 2]  # command, data_array

Receive Event

arduino.on :sysex do |command, data|
  puts "command : #{command}"
  puts "data    : #{data.inspect}" # data_array
end

Block Style

ArduinoFirmata.connect do
  puts "firmata version #{version}"

  30.times do
    an = analog_read 0
    analog_write 11, an
    sleep 0.01
  end
end