Converting ST mouse to USB?

[TheFloppyWizard]

I've got very little experience working with Ataris, but I thought it'd be a fun project to try and convert one of my ST mice to USB so I can use it on a modern computer. I've been using a 5V/16MHz ProMicro for this and the pinouts described here: http://old.pinouts.ru/Inputs/atari_st_j ... nout.shtml

I've just been trying to understand the signals from each of the wires by printing out what my ProMicro sees from there through analogRead() and digitalRead().

Some interesting problems/observations I've been running into:
- None of the pins seem to be analog, they're all digital.
- No matter what I do, I can't get either of the mouse buttons to register. However, they sometimes display a signal when messing with the X/Y wheels.
- According to the linked pinout, each pin related to mouse movement are only responsible for one of +X, -X, +Y, -Y. However, these pins display a signal no matter which way I turn their respective X/Y wheel. I'm having trouble discerning a pattern and confirming that the linked pinout is correct.

Does anyone know if there's something tricky about these mice that I'm not accounting for? I've used this mouse with a 520ST and confirmed that it works properly.

[tzok]

Forget about DigitalRead(), it is far too slow for encoder. Before you start coding you have to understand how the mouse works... you distinguish directions on a base of the phase shift between +X/-X pulses. Of course these are "digital" (square wave) signals. Buttons shouldn't be problem, but they are active low, so pull-up is required on the receiver side. There is a SM-1 schematic on the web - find it, look at it, and and understand how it works.

...it'd be easier for you to just put a USB (and possibly optical) mouse electronics into SM-1 case.

[wongck]

Have you seen this doc?
http://www.atari-wiki.com/index.php/Keyboard_Protocol

not sure if it helps.

[czietz]

As tzok already wrote, X/Y signals work like this: https://en.wikipedia.org/wiki/Increment ... re_outputs

[mjw333]

read up : https://sourceforge.net/p/steemsse/code ... d.txt#l460
especially location fb8e onward.