Raspberry PIにPyCallをインストールしてRubyからGPIOのPython用ライブラリを使ってみる ref: http://qiita.com/mix_dvd/items/778e6f3f63202c147609

file0.sh

$ sudo apt install -y ruby-dev
$ sudo gem install --pre pycall

file2.txt

$ python gpio_input.py
press ^C to exit program ...
1
1
1
0
0
1
1
1
0
1
1
^Cdetect key interrupt

Program exit
$

file4.txt

$ ruby gpio_input.rb
press ^C to exit program ...
ON(1)
OFF
ON(2)
OFF
ON(3)
OFF
^Cdetect key interrupt

Program exit
$

gpio_input.py

#!/usr/bin/python

import RPi.GPIO as GPIO
import time

IO_NO = 4

print("press ^C to exit program ...\n")

GPIO.setmode(GPIO.BCM)
GPIO.setup(IO_NO, GPIO.IN)

try:
 while True:
  print(GPIO.input(IO_NO))
  time.sleep(1)
except KeyboardInterrupt:
 print("detect key interrupt\n")

GPIO.cleanup()
print("Program exit\n")

gpio_input.rb

require 'pycall/import'
include PyCall::Import

pyimport 'RPi.GPIO', as: 'gpio'

io_no = 4

status = 1
buff = 1

cnt = 0

puts "press ^C to exit program ...\n"

gpio.setmode.(gpio.BCM)
gpio.setup.(io_no, gpio.IN)

# 「Ctrl」+「C」で停止させる
Signal.trap(:INT) do
  puts "detect key interrupt\n"
  gpio.cleanup.()
  puts "Program exit\n"
  exit 0
end

loop do
  status = gpio.input.(io_no)
  if buff != status
    if status == 1
      puts "OFF"
    else
      cnt += 1
      puts "ON(#{cnt})"
    end
  end

  buff = status
  sleep 0.5
end