I am currently writing a control and monitoring software system that makes use of GPIO pins. Since I was at the CCC congress in Berlin I did only have my laptop and no real GPIO hardware...
With only a laptop it's a bit hard to write GPIO software, since laptops usually don't have any GPIO pins. So what I needed to test my new software was either a real device (out of reach) or... writing a simulator.
<Nick> What is a GPIO Simulator?
<kettenis> You write to a pin and nothing happens...
