Capacitive sensing in short is the art of detecting the relative amount of capacitance (think capacitor) connected to a pin on your microcontroller. So, what the hell does that mean and why is it worth blogging about?
Practically speaking, capacitive sensing techniques are typically used to create buttons without a mechanical switch. Basically, when you design your PCB you include special traces that do the sensing. When a finger, or a nose or whatever gets close to the sensing trace, the software in the micro controller senses a shift in the capacitance of the trace. This shift in capacitance is what the micro uses to determine if the user has activated the "button". These sensors can take many forms. Usually they are hidden below a layer of plastic, with some sort of icon printed on it. I have even seen sensors made of conductive ink that has been drawn on!
Chances are you own something that utilizes a capacitive interface. For example, the iPhone uses a thin, transparent membrane embedded with an array of tiny electrodes that it uses to sense where your finger is at on the display. If you fool around sometime, you can actually get the iPhone to detect your finger even if its not physically touching the screen. This is the beauty of capacitive sensing. There is a lot of "tunable" parameters that you can change to influence the behavior of the interface.
There are gobs of cool applications out there, the possibilities are almost limitless!
Read on to discover how it works!
