In the first article of this series we saw how easy it is to connect your own circuitry to an Android smartphone using the AndroPod interface. Our aim there was to make the software aspects as simple as possible for all users. Building a user interface for your own project with HTML is very easy if your use our free Android app. As always with Elektor, the app software can be downloaded free of charge, and you can modify it if necessary because everything is open source.