Converting ST mouse to USB?

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Converting ST mouse to USB?

Postby TheFloppyWizard » Fri Jun 07, 2019 12:33 am

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:

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.

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Re: Converting ST mouse to USB?

Postby tzok » Fri Jun 07, 2019 8:55 am

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

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Re: Converting ST mouse to USB?

Postby wongck » Fri Jun 07, 2019 8:58 am

Have you seen this doc?

not sure if it helps.
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Re: Converting ST mouse to USB?

Postby czietz » Fri Jun 07, 2019 10:52 am

As tzok already wrote, X/Y signals work like this: ... re_outputs

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Re: Converting ST mouse to USB?

Postby mjw333 » Fri Jun 07, 2019 2:37 pm

read up : ... d.txt#l460
especially location fb8e onward.

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