Simulating a washing machine

Into the face of the young man who sat on the terrace of the Hotel Magnifique at Cannes there had crept a look of furtive shame, the shifty, hangdog look which announces that an Englishman is about to talk French.

Mike Ritchie gave a presentation at tonight’s BCS Edinburgh branch meeting. He was talking about the peculiarities of developing embedded software (the computer programs that control the behaviour of physical devices such as ovens, light bulbs, pacemakers, televisions).

He has designed and built an electronic circuit board that simulates a simple washing machine. It has buttons and dials and lights to make it easy to demonstrate selecting a wash cycle, closing the door, filling with hot water, spinning to dry and so on.

Using these “washing machines”, he showed how the control software can be developed and tested on a general purpose computer. Every time the developer changes the software it is automatically built, installed and tested on the hardware. A really nice demonstration of continuous integration.

Then he talked about how you can dig into the hardware to really understand how your software is behaving. There’s fancy monitoring programs to track its performance, and there is assorted electronic kit, such as multimeters and logic analysers, to investigate with when things go wrong.

A wistful look came over him when he spoke of a diagnostic device that he would like to add to his toolkit, called the Chip Whisperer. It would be nice to think that Santa might get it for him, but with a price tag of several thousand pounds that seems unlikely.