Embedding Ruby into your Daily Life

Many Rubyists know Ruby for its ease of use as a web scripting language. Many sysadmins know Ruby for its server provisioning capacity and as a glue language to the shell. Many Rubyists don't know about how Ruby can be used in the world of embedded computing and microcontrollers to assist your daily life. Mruby expands the capabilities to robotics and hobby electronics, as well as small-scale automation. Learn about ways to embed ruby into your daily life with heat control, plant watering, helpful robots, and more.

Transcript

1. Embedding Ruby into
   your Daily Life
   Andrew Nordman
   Saturday, August 3, 13
   

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2. Andrew Nordman
   cadwallion
   cadwallion
   cadwallion
   109019649444191303770
   Saturday, August 3, 13
   

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3. • eLearning Technology Company
   • Work Training, Compliance, Learning
   • Software Engineer
   • We’re Hiring
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4. • Nanobrewery
   • Small-batch, Diverse Beer
   • Co-Founder / Brewer
   • We’re Not Hiring
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5. • Father of Two
   • Sleep Deprivation Tool
   • I Wish We Were Hiring
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6. Saturday, August 3, 13
   

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7. Let’s Just Be Friends
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8. Embedded Systems
   A computing component
   embedded within a larger
   electromechanical system or
   device.
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9. Voltage Logic
   Component
   CPU
   Here’s 3.3V @ 40mA!
   Oh? Then, here’s 5V
   @ 40mA!
   Why so LOW? Not
   enough to trigger me
   to HIGH state.
   Much better, setting
   to HIGH state.
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10. Subsystems
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11. Can we apply SOA concepts to physical
    computing?
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12. General Purpose I/O
    • Expansion pins on a development board
    • Programmable voltage control
    • Accessible via UNIX file handles
    echo “17” > /sys/class/gpio/export
    echo “out” > /sys/class/gpio/gpio17/direction
    echo 1 > /sys/class/gpio/gpio17/value
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13. Arduino
    • Atmel Virtual Runtime
    • Small SRAM
    • Too small for CRuby :(
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14. Raspberry Pi
    • Low-Cost Computer ($25-35)
    • Runs Custom Debian Installation
    • Aimed at Education
    • 26 available GPIO pins
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15. BeagleBone Black
    • $45 Development Board
    • Custom Linux Distribution
    • 92 GPIO pins
    • Built-in Cloud9 IDE
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16. WiringPi-Ruby
    https://github.com/WiringPi/WiringPi-Ruby
    require ‘WiringPi’
    IO = WiringPi.new
    inputPin = 1
    outputPin = 2
    IO.mode(inputPin, INPUT) # YUNO NAMESPACE GLOBALS
    IO.mode(outputPin, OUTPUT) # SRSLY
    value = IO.read(inputPin)
    IO.write(outputPin, value)
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17. Brewby
    +
    • Brewery Automation System
    • Useful for Commercial & Homebrewers
    • Rack app monitors and triggers events
    • Client app interfaces with GPIO
    • Logs
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18. KeepMeAlive
    • Plants die at our house
    • Tired of killing plants
    • Monitors plant moisture level
    • Sends SMS at certain threshold
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19. KeepMeAlive.Animal
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20. KeepMeAlive.Animal
    • Modified Cereal Dispenser
    • Controls dispensing with Servo Motor
    • Uses Rails app to Schedule Feeding
    • Possible Improvements?
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21. Drawbacks to Ruby
    • CRuby relies on “full” operating system
    • CRuby memory usage is large*
    • CRuby is slow*
    * compared to microcontroller RTOS
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22. Alternative Approaches
    • Delegate to microcontroller units (MCUs)
    • mruby
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23. Delegate to MCUs
    • Ruby controls the main state machine
    • MCU controls an isolated subsystem
    • Use I2C communication protocol
    • Arduino!!! :D :D :D
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24. ATMega328P
    • MCU behind the Arduino Uno dev board
    • 14 Digital IO pins, 6 Analog Pins
    • Arduino Uno - $30
    • ATMega328P - $2 + $3 in parts to run
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25. • Subset of Ruby API
    • Built with embedded appliances
    • No assumption of threaded OS or FS
    • Cross-build to specific targets
    • Very small footprint (~80KB RAM usage)
    • Code dependencies compiled into bin
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26. Mruby’s small footprint is because it cut out a lot.
    CRuby Mruby
    File/IO, require, multithreading, readline, RubyGems support...
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27. MGem
    • Mruby answer to code packaging
    • Library can contain ruby or C code
    • Many authors have implemented the
    missing Ruby components for mruby in
    mgems
    • STDLIB is a series of mgems
    • https://www.github.com/bovi/mgem-list
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28. Adding an mgem to
    mruby
    MRuby::Build.new do |conf|
    conf.gem ‘mruby-pid’, :github => ‘cadwallion/mruby-pid’
    conf.gem ‘/home/cadwallion/code/mruby_example_gem’
    end
    build_config.rb
    mirb - Embeddable Interactive Ruby Shell
    This is a very early version, please test and report errors.
    Thanks :)
    > PID
    => PID
    >
    mruby/bin/mirb
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29. Cross-Build Mruby to
    Targets
    • Builds mruby on a target toolchain for
    deployment
    • Opens up opportunity to build for new
    runtimes
    • Which means....
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30. ARDUINO?!?
    MRuby::CrossBuild.new do |conf|
    # A LOT OF SETUP
    conf.cc do |cc|
    # CC compilation options for Arduino
    end
    conf.cxx do |cxx|
    # CXX compilation options for Arduino
    end
    conf.archiver do |ar|
    # Archiver options for Arduino
    end
    conf.gem :github => ‘kyab/mruby-arduino’, :branch => ‘master’
    end
    For more full version, https://github.com/mruby/mruby/blob/master/examples/targets/ArduinoDue.rb
    build_config.rb
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31. Steps to push Ruby
    code to Arduino
    • Write ruby code
    • Use `bin/mrbc` to compile to bytecode
    • Write C to kickoff bytecode in mruby VM
    • Upload C code to Arduino
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32. #include
    #include “mruby.h”
    #include “mruby/class.h”
    #include “mruby/value.h”
    #include “mruby/irep.h”
    mrb_state *mrb;
    mrb_value rover_obj;
    extern const uint8_t rover[]; // ruby bytecode
    void setup() {
    mrb_load_irep(rover); // eval bytecode
    RClass *rover_class = mrb_class_get(mrb, “Rover”);
    mrb_value args[6];
    args[0] = mrb_fixnum_value(2); // Motor1Pin1
    args[1] = mrb_fixnum_value(3); // Motor1Pin2
    args[2] = mrb_fixnum_value(4); // Motor1PwmPin
    args[3] = mrb_fixnum_value(5); // Motor2Pin1
    args[3] = mrb_fixnum_value(6); // Motor2Pin2
    args[3] = mrb_fixnum_value(7); // Motor2PwmPin
    rover_obj = mrb_class_new_instance(mrb, 6, args, rover_class);
    mrb_funcall(mrb, rover_obj, ‘run’, 0);
    }
    void loop() {
    // no-op, Ruby handles all the fun here
    }
    class Rover
    def initialize(m1p1, m1p2, m1pwm, m2p1, m2pwm)
    @left_wheel = Wheel.new(m1p1, m1p2, m1pwm)
    @right_wheel = Wheel.new(m2p1, m2p2, m2pwm)
    end
    def run
    @goForward()
    end
    def goForward()
    @left_wheel.setMotor(:forward)
    @right_wheel.setMotor(:forward)
    end
    end
    class Wheel
    def initialize(pin1, pin2, pwmPin)
    @forwardPin = pin1
    @backwardPin = pin2
    @speedPin = pin3
    end
    def setMotor(direction)
    if direction == :forward
    Arduino.analogWrite(@speedPin, 255)
    Arduino.digitalWrite(@forwardPin, Arduino::LOW)
    Arduino.digitalWrite(@backwardPin, Arduino::HIGH)
    end
    end
    end
    Rover Example
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33. Always Be Coding...
    ...Robots*.
    * I am not to be held responsible for the birth of SkyNet by following this advice.
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34. More Questions?
    Find the Red Mohawk.
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