Simple controls in Ruby for controlling the GPIO pins on RaspbPi (reference: http://elinux.org/images/2/2a/GPIOs.png)

raspbpi-gpio.rb

def with_pin(pin)
  begin
    puts "Connecting..."
    export(pin)
    direction(pin, "out")    
    yield(pin)
  ensure
    puts "Disconnecting..."
    unexport(pin)
  end
end

def echo(input, gpio_file); `echo "#{input}" > /sys/class/gpio/#{gpio_file}`; end
def export(pin); echo(pin, "export"); end
def unexport(pin); echo(pin, "unexport"); end
def on(pin); echo(1, "gpio#{pin}/value"); end
def off(pin); echo(0, "gpio#{pin}/value"); end
def pwm(pin, value); echo(value, "gpio#{pin}/value"); end # only GPIO18 is PWM, 0
def direction(pin, direction="out"); echo(direction, "gpio#{pin}/direction"); end