Author: Nick McComb | www.nickmccomb.net
Pulse Width Modulation is a very useful, and simple, protocol that communicates using “pulses” of high signals. These are used in everything from Hobby Servos to LED Dimming (and countless other applications).
It can be generated using hardware, or active devices such as a Microcontroller or 555 timer.
The following Pololu articles provide a good introduction to the protocols, and instructions for it’s use.