Messing with an MS-Mouse

[MM007]

I've been entertaining the idea of trying to make an NES controller into a PS/2 mouse, so I took apart an old Mouse Port MS Mouse, 2.1a, and started messing around.

I had the intention of trying to find which leads to short on the IR sensors (or even the IR leds) to get up, down, left, and right, and connect them to a clock when pressed to make the cursor move. It seemed simple enough...except that instead of finding out how to short four different places to get four directions, I found only two places to short, one that often gives me "up" but sometimes "down", and one that gave me "right" but sometimes "left". They correspond to the respects axes of the mouse.

Does anyone know what I need to do to get the four directions of the mouse to work independantly? I googled the mouse and didn't find much, and then I checked the control chip's data sheet and got nothing I could understand, as it is a programmable chip (I don't know what pins mean what in this case because of that). Anyone able to shed light on this?

There may be another lead somewhere, maybe a one bit value to determine whether or not the direction is left/right or up/down somewhere, possibly called XS and YS...

[timmeh87]

hm. these "two places to short" might be more like "two data lines", where the direction is determined based on some rising/falling edge triggering, combined with some timing. or something like that. im thinking back to how the n64 controller communicates..

http://instruct1.cit.cornell.edu/course ... 7/lld.html

so as you can see there, the falling edge signifies the beginning of a bit, and then the length of time to the rising edge determines the value (1 or 0). the mouse probably dosent use this system, but could be something similar. it would be helpful if you could put a scope to it and operate it normall to see what kind of signals are going into those pins.