Regular mice drop count all the time anyways, so you can expect it to drift off after a while. I did the same thing back in the day, but I hooked the optical mouse sensor directly to an ATMega so ...

Why this hasn't been done before is a mystery to me. This little hack project by Kellbot of NYCResistor takes a rolling ball, an optical mouse, a gutted PS2 controller, and some Arduino hacking ...

The Arduino is converting the mouse actions into 8 digital signals fed to an IO expander (The 6522 VIA) and raises an interrupt. The 6502 reading the resulting value from the VIA and decoding that ...