|Version 3 schematic||(png)|
|Version 3 source code||(tar file compressed with bzip2)|
|Version 3 notes||(plain text)|
|Version 1 schematic||(png)|
|Version 1 source code||(tar file compressed with bzip2)|
|Version 1 notes||(plain text)|
OK, now finished debugging Version 2 of the POV thingy.
I've upgraded to the ATmega168 MCU with 16K of flash, which has eight times more memory than the V1 board had with its ATtiny2313 (but it's still easy to run out!). I've added a hall effect rotation sensor to track wheel movement. Added code to stabilize the image (in scale and translation) regardless of wheel speed. Added code to calculate speed in miles per hour and distance traveled in miles. The distance function should be extremely accurate, but the speed will be ballpark only because the internal clock on the MCU isn't very accurate. I can add an external crystal to make this spot-on, but it's not that big a deal to me. In an 8-mile test, my display was off by 6% from a normal bike computer. I can certainly live with that.
Next step is to make a duplicate V2 board and run them both on the same wheel, positioned on the same side but opposite each other. This will cause the image to look much better, especially at slow speeds.
|Here's a shot of the speed/distance display in action.|
I recently completed my P.O.V. (Persistance of Vision) project. A POV device flashes lights in a pattern very quickly. When the device is put into motion (perhaps by attaching it to a wheel or even just holding it and swinging your arm in a wide arc), the timing can be adjusted such that the light patterns form words or graphical images.
I used the AVR ATtiny2313 micro controller and some old amber super-bright LED's for this project. I attached the tiny circuit board to the back wheel of my bicycle and turned the pedals to put the device in motion. Please see the pics below: