Every once and a while someone uses PHP for something interesting and different than the usual web application. In this post to his site Thomas Weinert shares an example - he uses PHP to control a LED via Carica Chip.

Some time ago, in this blog post, I explained the basic stuff about Arduino, Firmata and PHP. Now it is time for the next step. Carica Io and Carica Firmata have grown and got a third layer called Carica Chip. [...] Carica Chip provides an easy way to control a device. So let's start with an "Interactive LED" example.

He uses the Carica Chip library and the "skeleton" application command from Composer to make a basic application. A simple HTML page with on and off links is made and and basic Carica Chip server is set up and executed. It's a simple example, but it gives you an idea of how to set it all up. The Carica Chip package also allows for other interactions including working with servos and motors.