Evil Mad Scientist Laboratories writes -
The last decade has seen more than an order of magnitude drop in the price of accelerometers, devices capable of measuring physical acceleration (often in more than one direction). History suggests that whenever a useful technology makes a precipitous drop in price, unexpected applications follow, and that’s exactly what has happened in this case.
Starting from zero and summing up acceleration, you can use an accelerometer to find velocity, and from that derive relative position information. By measuring the acceleration due to gravity, one can also determine orientation (technically, inclination)– you can tell which way it’s pointing. Those are pretty useful skills for a chip! And so as bulk prices for tiny chip-scale three-axis accelerometers have begun to approach $5, they have started to appear in all kinds of mass-market applications that you might not have predicted: laptop computers (for hard drive protection), smart phones and cameras (for orientation– e.g., portrait vs. landscape on the iPhone), cameras for image stabilization, and quite visibly in the controllers for Nintendo’s Wii system.
With all that promise, you might think that an accelerometer is a difficult beast to harness. That turns out not to be the case. In this little project we demystify the mighty accelerometer and show you how to get started playing with one. In the spirit of hobbyist electronics we do this the easy way– without designing a PCB or even soldering any surface-mount components.
Using an ADXL330 accelerometer with an AVR microcontroller – Link.