ev3dev ruby binding for LEGO Mindstorms EV3

ev3dev_ruby is a gem to controll sensors and motors on EV3 using Ruby on ev3dev OS.
ev3dev OS is a Debian Linux-based operating system for LEGO Mindstroms EV3.

• ev3dev OS version; ev3dev-stretch

Install ev3dev OS

See ev3dev OS website

Install ev3dev_ruby on EV3

SSH remote access to the EV3 from PC

(default ev3dev user; robot, password; maker)

$ ssh [email protected]

then

robot@ev3dev:~$ sudo apt-get update
robot@ev3dev:~$ sudo gem install ev3dev_ruby

Run examples

1. Copy the examples to the /home/robot directory in ev3dev from PC.

(for OS X user; )

$ scp -r /Users/xxx/Downloads/ev3dev_ruby-master/examples [email protected]:/home/robot

2. Run the program

There are two different ways to run the program.

A. Remote access from PC

robot@ev3dev:~$ cd /home/robot/examples
robot@ev3dev:~$ cd motor
robot@ev3dev:~$ ruby midiummotor.rb

B. File Browser on EV3

1. Add execute permission

robot@ev3dev:~$ cd /home/robot/examples
robot@ev3dev:~$ cd motor
robot@ev3dev:~$ ls -l
...
-rw-r--r-- 1 robot robot  474 Jan 18 16:18 midiummotor.rb
...
robot@ev3dev:~$ chmod +x midiummotor.rb
robot@ev3dev:~$ ls -l
...
-rwxr-xr-x 1 robot robot  474 Jan 18 16:18 midiummotor.rb
...

2. File Browser

Select the program and push the center button on EV3.

irb

You can also run programs using irb.

robot@ev3dev:~$ irb
irb(main):001:0> require 'ev3dev'
=> true
irb(main):002:0> mm = Ev3dev::Motor.new 'B'
=> #<Ev3dev::Motor:0x193890 @device_path="/sys/class/tacho-motor/motor0">
irb(main):003:0> mm.device_path
=> "/sys/class/tacho-motor/motor0"
irb(main):004:0> mm.driver_name
=> "lego-ev3-l-motor"
irb(main):005:0> mm.address
=> "outB"
irb(main):006:0> mm.commands
=> "run-forever run-to-abs-pos run-to-rel-pos run-timed run-direct stop reset"
irb(main):007:0> mm.stop_commands
=> "coast brake hold"
irb(main):008:0> mm.duty_cycle_sp 100
=> #<Ev3dev::Motor:0x193890 @device_path="/sys/class/tacho-motor/motor0">
irb(main):009:0> mm.command 'run-forever'
=> #<Ev3dev::Motor:0x193890 @device_path="/sys/class/tacho-motor/motor0">
irb(main):010:0> sleep 3

=> 3
irb(main):011:0> mm.command 'stop'
=> #<Ev3dev::Motor:0x193890 @device_path="/sys/class/tacho-motor/motor0">
irb(main):012:0>

ev3dev API

(Also checkout examples)

Motors

• EV3 Medium Servo Motor
• EV3 Large Servo Motor
• Tacho Motor Class API
• Tacho-Motor Class Tutorial

Sensors

• EV3 Touch Sensor
• EV3 Color Sensor
• EV3 Gyro Sensor
• EV3 Ultrasonic Sensor
• LEGO Sensor Class API

EV3 Devices

• Battery
• Sound
  • aplay (ALSA sound driver)
  • espeak (speech engine)
• LEDs
  • LED Transient Trigger
  • Original Led Class APIs are added. Checkout examples.
• Buttons
• Display
  • Original Screen Class and Image Class APIs are added. See Display_API.md and examples.

The EV3 device below are not supported yet.

• Bluetooth

More Info

• Getting Started with ev3dev - ev3dev.org