Sorry to butt in.

but i did something similar last week and so started reading the thread. Interesting discussions.

Since you are using raspberry pi4, have you though about using astroberry-diy focuser? I have not used this module, but from what i can gather going over the code, if requires one to hook up a motor driver to the pi, and use the indi-astroberry-focuser to control it. This driver allows you to select which GPIOs the motor driver is connected to. so i imagine it is a matter of getting a DRV8834/DRV8834/A4988/A4988 and hocking up the cables properly.

github.com/rkaczorek/astroberry-diy/

I did it somewhat differently, in that I had the motor driver, drv8825 in my case, connected and fpga and connected that to the indi by using a indi_fpga_focuser derived from the above-mentioned indi module. Please see the screenshot.

github.com/rsarwar87/indi-3rdparty/tree/master/indi-fpgafocuser
github.com/rsarwar87/CmodA7-SkyTracker


PS:
"I should probably mention that I run Linux Ubuntu everywhere I can, including the Pi, laptop and desktops."

i wish more would ditch windows and apple for linux. it is so much better compared to 10/20 years ago.

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