Mutilated mouse DRO (using Microsoft PS2 Mice)

Well in an effort to have a cheep DRO I figured I'd end up using the mouse encoders to interface with the parallel port using the DRO software that reads the parallel ports from http://www.lindsayengraving.com/other_interests/dro.html Using encoders from PS2 microsoft type mice

Anyway I couldn't find much out there on mouse mutilations that didn't use Logitech mice. And of course I've long since tossed all my Logitech mice which I liked a lot but simply wore out. But I do happen to have a LOT of MS mice.

Of course they are built different. The out put of their IR sensors is different then I think the Logitech ones are based on some of the schematics I've seen on the web.

The MS mice use 1 IR emitter and 1 sensor which has 2 outputs which produce the oscillating output signals to determine direction. The encoders used in the http://www.lindsayengraving.com/other_interests/dro.html I think output negative pulses which trip the PNP transistors to signal the 5v to the parallel ports. Looking at the Microsoft mouse circuit board it was kinda easy to see the sensors were going to send hi output when triggered rather then low so connecting to PNP transistors like they did on the lindsyengraving site wouldn't work.

Anyway I'm just dangerous enough with electronics and transistors to know when things work. But in any case in my experimenting I connected the Encoder signals from the MS mouse to some NPN transistors then watched how the LED's pulsed. Took a little bit to figure out which pin's of the mouse chip (once removed) needed to be used (follow the circuit board layouts) but once powered with 5v I was getting signals to the NPN transistors and was able to watch some connected LED lights blink on and off as I spun the wheel... Success.

Now the problem was to convert that signal to PNP so I could send 5v to the parallel port.

To do that I connected the output of the NPN transistors to some 4N25 optical isolators (pin 1 to the NPN transistor and 2 to ground). That triggered the optical transistor on the other side and that (pin 4 ground and 5 to PNP) triggers the PNP transistors . The rest of it is the same as Lindsy engraving's site. to the parallel port.


The mouse bodies are mounted to the mill and a simple rubber band running around the crank shafts with some PVC slipped and shrunk around the shafts to guide the band a little bit.. the band goes around the signal wheel triggers the signals. After getting it dialed in with the dro software it works Really good. Took something like a .00004725 count offset in the software to get it counting right with the signals.

I had a handful of mice to play with. and while the mouse chip for the most part had the same pin outs for reading the sensors (pin 1 and 2 for x and pin 3 and 4 for Y Pin 5 was positive) one of the mouse needed 6,11,12 to ground and the other just needed 6 and 12 and had an extra transistor on it which had to be removed and bridged with negative.

I did find how ever non of my P2 gate way boxes would work at all. Stupid gateway parallel ports not standard? Ended up using one of my P1 machines I have laying around.

Anyway sorry for the long post. Hopefully I will have some pictures of the work and schematics up soon. My descriptions of things probably isn't really good enough for the non brave to try but couldn't wait to talk about it.

b.





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