The project described in this article requires basic mechanical and electronics skills and is provided for information purposes. Do not attempt to replicate it or use it for any purpose unless you've got the proper knowledge and skills and are willing to accept the responsibility for your own actions.
One of the Raspberry special features is the GPIO (General Purpose Input / Output) a 26 pin connector to the outside world. This is where you connect external electronics devices to your Pi. It can be as simple as a LED, or as sophisticated as a factory automation system.
In theory you can connect electronics components directly to the GPIO pins, but in practice it’s best to have some kind of extension cable to an external circuit board. Commercial Raspberry Pi GPIO cables are available for $$$, but it’s easy to make your own for almost nothing.
Step 1: Find a Junk Computer
In almost all cases the ribbon cable which goes from that connector to the DB-25 connector on the back of the case only has 25 pins. You can use that cable as-is if you don’t need GPIO pin 26 (GPIO 7) or replace the cable with a 26 pin ribbon cable. If you’re using the original cable, slice off the DB-25 connector.
Step 2: Split Cable and Crimp on Connectors
Crimp one 16 pin DIP connector on to the 16 pin section, and the other connector on the 10 pin section.
Step 3: You're Done!
I use my Raspberry Pi as a home theater setup, with the popular RaspBMC software. With a little bit of hardware and programming, I can use RaspBMC to control external devices. Imagine using my remote (smartphone or infrared remote) to have my Pi dim the lights in the room before the movie starts, or even turn on a relay which turns on the hot air popcorn popper!