so ive been messing around with an old TV rotor I adapted for my 2m yagi and the manual control box is kind of a pain, especially when im trying to do satellite passes and need to track az/el in real time. been thinking about throwing an arduino in there with a couple of feedback pots and maybe talking to gpredict over serial but honestly im not sure where to start with the software side of it.

ive done some basic arduino stuff before, blinked some LEDs, read some sensor values, nothing crazy. the hardware side doesnt scare me too much but writing something that actually interprets the easycomm protocol and moves the motor accordingly feels like a lot. anyone done something like this or have a sketch thats at least close to what im describing? dont want to reinvent the wheel if someone already figured this out.

also considering just going raspberry pi instead and running rotctld but then i have to deal with linux on a pi which is fine i guess just more moving parts. not sure which way to go honestly.

yeah i did almost exactly this about two years ago. ended up going the arduino route for the actual motor control because the real-time loop timing is just cleaner than trying to do it from a pi, but i used the pi as the brains running rotctld and gpredict and had it talk to the arduino over USB serial. that way you get the best of both worlds — linux handles all the scheduling and the gpredict integration, arduino handles the PID loop and the pot reading without any OS getting in the way.

the easycomm II implementation on arduino isnt bad, theres a library floating around on github that gets you most of the way there. main thing i had to tune was the deadband on the pot feedback, mine was hunting back and forth like crazy until i put in about a 2 degree window before it would stop trying to correct. also watch your power supply, i was running the motor off the same 5v rail as the arduino initially and the voltage drop was doing weird things to the ADC readings. separate supplies fixed that pretty much immediately.

rotctld on the pi is honestly not that bad once you get it set up, ive been running a similar setup for a while now. the main headache is just making sure the serial port permissions are right so gpredict can actually talk to it without sudo. theres a udev rule you can add that fixes it permanently.

that said if youre already comfortable with arduino i dont see a reason to switch, just wire it up and grab one of the existing sketches and modify it. half the fun is messing with it anyway.