pin = 17

# make pin an input
GPIO.input(pin)

# check if the input is HIGH i.e. true
puts "door is closed" if GPIO[pin]

pin = 17

# make pin an output
GPIO.output(pin)

# blink
loop do
  GPIO[pin] = true
  sleep(1)
  GPIO[pin] = false
  sleep(1)
end

SPI.begin do |spi| 
  puts spi.read       # returns 1 byte
  puts spi.read(1024) # returns an array of 1024 bytes 
end

SPI.begin do |spi| 
  spi.write(0x22)           # write 1 byte
  spi.write("hello")        # write 5 bytes
  spi.write(0x22,0x45,0x71) # write several bytes at once 
end

File.open('/dev/ttyAMA0', 'a+') do |file|
  loop do 
    data = file.read
    file.puts(data)
  end
end