so ive been sitting on this idea for a while and finally started messing with it last weekend. basically i have an old prop pitch rotator that works fine mechanically but the controller died years ago and replacements are stupid expensive. figured i could just roll my own controller using an arduino mega and a couple of IBT-2 motor driver boards since those can handle the current.

got it mostly working actually, the PID loop is tuning the position feedback from a 10-turn pot geared to the rotator shaft and im reading the voltage with the analog pins. accuracy is pretty decent, maybe plus or minus 2 degrees which is fine for anything above like 50mhz. the part im struggling with is the PC interface. i want to talk to it over serial using the Yaesu GS-232 protocol so it'll just work with existing logging software like N1MM or Ham Radio Deluxe without needing custom drivers or whatever.

anyone done this before? i found a few old github repos but most of them are like 5 years old and either abandoned or written by someone who clearly just learned arduino the week before. wondering if theres a cleaner implementation out there or if i should just write it from scratch at this point

yeah i did basically this exact thing about two years ago for a satellite setup. ended up writing my own GS-232 parser from scratch because honestly the ones i found online were a mess — half of them didnt implement the full command set and the other half had weird timing bugs that would cause N1MM to lose sync every few minutes.

the protocol itself isnt that complicated once you sit down and actually read through the spec. the main commands you need for basic azimuth/elevation are M, C, S, and A and thats honestly it for most software. i wrote a simple state machine to parse incoming serial bytes and it worked first try pretty much. if you want i can dig up the repo, i think i cleaned it up at some point. the tricky part for me was debouncing the feedback pot reading because i was getting noise from the motor driver coupling back into the analog lines — ended up just running shielded wire for the pot and that mostly fixed it.

2 degrees is totally fine btw, my yagis have like 15 degree 3dB beamwidth at 2m so its not like you need arcsecond precision here

have you looked at the antenna rotator controller project that W4/VE3KL or whoever published on QRZ a while back? cant remember who it was exactly but there was a pretty well documented one using a Raspberry Pi instead of arduino, talked to rotctld directly which is nice if youre running linux. might be overkill depending on what you want though, arduino is probably fine if you dont need the network stuff