so i finally got fed up with the old controller for my yaesu G-450A and started messing around with an arduino mega to build something smarter. been at it for about 3 weeks now and honestly its both the most fun and most frustrating thing ive done in the hobby in a long time

the basic idea is pretty simple — read the pot voltage from the rotator, convert it to degrees, and then drive the motor relay outputs based on where i want to point. sounds easy right. except the pot in mine is super noisy and i keep getting jitter in the readings so the thing keeps hunting back and forth by like 2-3 degrees even when its supposed to be stopped. ive got a 10uf cap across the pot leads and tried averaging 50 samples in the ADC loop but its still twitchy. running it through a voltage divider to get the 0-4.5v range into the arduino 5v ADC

the longer term goal is to tie it into a raspberry pi 4 that would run hamlib rotctld and maybe flrig, so i could have the whole station automated — point the antenna based on what dx cluster is showing, log it, the whole deal. ive seen a few projects online doing similar stuff but most of them are half documented and you cant really figure out what they actually did

anyone gone down this path and have tips on the noise issue specifically? or just general thoughts on the arduino/pi combo for this kind of thing. im running arduino IDE 2.x and the pi is on bookworm if that matters

yeah the jitter thing is classic with those pots, especially on older rotators. the cap helps but honestly what worked way better for me was adding a small deadband in software — like if the current position is within 2 degrees of the target just dont fire the relay at all. your pointing accuracy on a yagi at HF isnt gonna care about 2 degrees anyway and it stops that hunting behavior completely

also try increasing your sample averaging a lot more, i was doing like 200 samples and throwing out the top and bottom 10% before averaging the rest. adds a tiny bit of latency to the position reading but for a rotator thats completely irrelevant. the other thing is make sure your analog ground is solid — ive had cases where relay switching was inducing noise into the ADC ground reference and filtering wasnt gonna fix that no matter what you did

the hamlib rotctld integration on the pi side is actually pretty straightforward once you get the arduino presenting itself as a serial device with the right command format. i used the easycomm II protocol as a template, hamlib supports it natively and you dont have to write a custom backend. theres a guy on github with an arduino sketch that does exactly this, search for arduino rotator easycomm and youll find it pretty quick

i did something similar with a cheaper rotator and a pi zero W a couple years ago. worked great until i fried the zero by accidentally putting 12v on a gpio pin which was a bad day. anyway the deadband suggestion above is the move for sure

one thing i'd throw out there — depending on how far you wanna take the automation side, home assistant can actually talk to hamlib through some community integrations and then you can build automations around it with a pretty nice UI. kind of overkill maybe but i ended up with a dashboard on an old tablet in the shack that shows beam heading, current band, and a few other things. my wife thinks its ridiculous but whatever it works