so ive been messing around with this for a few weeks now and im starting to wonder if i'm overcomplicating it. basically i have an old yaesu g-450a rotator and the controller is functional but i want to be able to drive it from the shack PC, maybe tie it into WSJT-X or at least have it track az/el from a file or something. i saw a few projects online where people used an arduino mega with some relay boards and a voltage divider on the feedback pot to read the heading, seemed straightforward enough.

problem is i keep getting weird readings on the analog input, like it'll say 180 degrees but the antenna is clearly pointing somewhere else and it drifts around. i checked the wiring twice and the pot voltage looks reasonable on the meter but something is just off. using a 10-bit ADC on the uno isnt helping i think, or maybe my voltage reference is just noisy. running off USB power which is probably not ideal.

has anyone actually got one of these working reliably? wondering if i should just spend the $30 on one of the commercial arduino-based rotator controller boards or keep hacking at it myself. also thought about maybe throwing a raspberry pi in there so i could run hamlib rotctld natively but that feels like scope creep at this point

yeah the USB power thing will absolutely cause you grief, the 5v rail on those boards is pretty dirty especially if you have relays switching on the same supply. i did almost exactly this project last year with a G-650 and the first thing i did was put a small LC filter on the AREF pin and use an external 3.3v regulator as the reference — made a huge difference. also worth putting a 100nF cap right at the wiper of the pot to ground, that cleans up a lot of noise before it even hits the ADC.

the pi idea isnt really scope creep if you think about it, because then you just run rotctld as a service and any software that speaks hamlib just works. i run mine headless with a little python script that polls the arduino over serial and translates to the rotctld protocol. took a weekend to get solid but its been running for like 8 months without a restart so

dont bother with the commercial boards imo, half of them are just someone else's arduino project in a box and you lose the ability to tweak the code. the learning is worth it if you have the time. that said if your deadline is a contest or something just buy the N1MM rotator interface and call it a day