Intro, idea, schematic
First of all, sorry bout the crappy schematic and the un-vacuumed floor, I made this page ages ago just to show the mat off to a few friends; the page was never meant to be viewed by the world at large. Ah well, you're here now anyway...
Intro
For people who don't know what DDR means: DDR is an abbreviation of Dance Dance Revolution, an arcade game which is really popular in some parts of the world. Use Google if you want to know more about it.
My brother has a DDR mat which interfaces with his PC. It's nice, and you can play games like StepMania really good on it, but I know if I got myself one, it would be all around the room irritating me when I wouldn't use it. So i thought about a less obvious DDR mat... and this is what I came up with: The stealth DDR mat. It even is cheaper than a store-bought DDR-mat.
The Big Idea
I've been working with an IC called the QT160, that's specially developed for touchless switching-applications. This IC would be perfect for this application, all you need to do is put a metal sheet behind anything you want to act like a switch. The 3 problems: First of all, I'm not sure if the chip'll work with a metal sheet of 40x40 cm. Secondly, it's not really widely available and thirdly, I didn't have one lying around when I made this. So I decided I'd have to build my own touch-controller, which in the end was easier than I thought.
After an evening of thinking I came up with the following schematic:
To the right one can see the gameportconnector, from which the circuit draws it's power and sends the info to. The power is stabilised by 2 capacitors, one of 100uF and one of 100nF. In the middle of the schematic is the microcontroller, an Atmel AT90S2313, running at 8MHz, provided by the crystal on the right, which is decoupled by 2 22pF capacitors. To the left are four leds indicating which pads are stepped on. (handy for calibration) The calibration is done with the 4 50k 10-turn-trimmerpots above the LEDS, and are only needed the first few times: after these are tuned 'about right', the circuit is sortta self-calibrating. The pads are the circles completely to the right.
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