We thought that connecting an Arduino to a Raspberry Pi was overkill ... [Jan] uses the PHP serial class to communicate between the RPi and Arduino (dead link; Internet Archive).

Not only does the Raspberry Pi sport more I/O pins than the Arduino, but it has a good range of communication ports, too. You can effortlessly add internet connectivity to your Raspberry Pi using ...

and even serve as a serial monitor where you can print messages. If you're more interested in programming with C/C++, there's an 88-page guide you can refer to. The Arduino Nano and Raspberry Pi ...