Fun with Ruby and a Raspberry PI

fun.rb

require 'pi_piper'
require 'ostruct'

laser = PiPiper::Pin.new(pin: 17, direction: :out)
alarm = PiPiper::Pin.new(pin: 18, direction: :out)
vibration = PiPiper::Pin.new(pin: 27, direction: :in)
i2c = PiPiper::I2C.new

def turn_on(pin)
  pin.off
end

def turn_off(pin)
  pin.on
end

def read_channel(i2c, number)
  value = Integer("#{40 + number}", 16).chr.bytes
  i2c.write(to: 0x48, data: value)
  i2c.read(1)
  i2c.read(1)
end

class Rule < OpenStruct
  def check
    value = read_fun.()
    # puts "#{name} = #{value}"

    if trigger_fun.(value)
      puts "#{name} was triggered! Value = #{value}"
      return true
    end
  end
end

RULES = [
  Rule.new(
    name: 'laser',
    read_fun: ->() { read_channel(i2c, 0).first },
    trigger_fun: ->(value) { value > 50 }
  ),
  Rule.new(
    name: 'temperature',
    read_fun: ->() { read_channel(i2c, 1).first },
    trigger_fun: ->(value) { value < 115 }
  ),
  Rule.new(
    name: 'sound',
    read_fun: ->() { read_channel(i2c, 2).first },
    trigger_fun: ->(value) { value < 100 }
  ),
  Rule.new(
    name: 'vibration',
    read_fun: ->() { vibration.read },
    trigger_fun: ->(value) { value.zero? }
  )
]

begin
  turn_on(laser)
  turn_off(alarm)

  loop do
    sleep 0.2

    if RULES.find(&:check)
      turn_on(alarm)
    else
      turn_off(alarm)
    end
  end
rescue Interrupt
  puts "Exiting, bye friend!"
ensure
  turn_off(laser)
  turn_off(alarm)
end