LED OnOff by Cds cell

require 'wiringpi2'

$a_pin = 1  #18
$b_pin = 4  #23
$led_pin = 0 #17

def discharge
  io = WiringPi::GPIO.new do |gpio|
    gpio.pin_mode($a_pin, WiringPi::INPUT)
    gpio.pin_mode($b_pin, WiringPi::OUTPUT)
  end
  io.digital_write($b_pin, WiringPi::LOW)
  sleep 0.005
end

def charge_time
  io = WiringPi::GPIO.new do |gpio|
    gpio.pin_mode($b_pin, WiringPi::INPUT)
    gpio.pin_mode($a_pin, WiringPi::OUTPUT)
  end
  io.digital_write($a_pin, WiringPi::HIGH)
  count = 0
  while io.digital_read($b_pin) == 0
    count += 1
  end
  count
end

def analog_read
  discharge
  charge_time
end

def led_on
  io = WiringPi::GPIO.new do |gpio|
    gpio.pin_mode(0, WiringPi::OUTPUT)
  end
  io.digital_write(0, WiringPi::HIGH)
end

def led_off
  io = WiringPi::GPIO.new do |gpio|
    gpio.pin_mode(0, WiringPi::OUTPUT)
  end
  io.digital_write(0, WiringPi::LOW)
end

while 1
  light = analog_read 
  light > 70 ? led_on : led_off
  puts light
  sleep 1
end