Pi Facer brings event driven programming to the Raspberry Pi's PiFace accessory.
Pi Facer was designed for Ruby 2.0! Pi Facer was based and inspired on Pi Piper and uses piface, and such is still alpha as piface is.

To get started:

To install Pi Facer:

sudo gem install pi_facer

PiFace Digital plugs directly onto the top of your Raspberry Pi, and allows you to sense and control the real world. 2 Changeover relays 8 Open-collector outputs 8 Digital inputs 8 LED indicators 4 Switches Graphical emulator and simulator

require 'pi_facer'
include PiFacer

watch :io => 3 do
  puts "FIO changed from #{last_value} to #{value}"
end

PiFacer.wait

Your block will be called when a change to the pin's state is detected.

Additionally you can use the outputs too:

pin = PiFacer::FIO.new(:io => 1, :direction => :out)
pin.on
sleep 1
pin.off

Proudly developed exclusively on a Raspberry Pi