I'm working on an interface that uses a mouse board tied into a vehicle speed sensor(VSS) in order to gather data about a car's movement, and need to read this info in my program. I chose the circuitry from a mouse because of its simplicity, my problem is that I need to watch for a change in x or y(depending on where I hook it up) and record the time between the two. I've see several mouse examples, but most only report between 0-79(for each character of an 80-line display) and I need the most precise number I can get(I'm hoping for each individual trigger of the beam) If anyone can point me in the right direction, or can help me out, I'd really appreciate it.

BTW, in case some of what I'm trying to accomplish seems unclear, the mouse circuitry i'm using is from a serial type that has two large toothed wheels inside that follow the ball, with sensors at the teeth that detect light passing through each tooth. What I'm going to be doing is hooking the VSS in place of that sensor so that each trigger of the VSS would sount as one tooth passing the sensor.


Thanks for any help!