so ive been messing around with this for a few weeks now and i think im finally getting somewhere but wanted to see if anyone else has gone down this rabbit hole. basically i have an old prop pitch rotator that a buddy gave me and the original controller is toast, like completely dead, so i figured instead of buying a replacement controller i'd just build one around an arduino mega since i had one sitting in a drawer.

the motor is a dc brush type so i wired up an H-bridge module, one of those cheap L298N boards, and im feeding position feedback from a 10k pot i coupled to the rotator shaft with some 3d printed gears. the analog read from the pot goes into one of the arduino's ADC pins and i'm mapping the voltage to degrees which seems to work pretty well on the bench. the part im stuck on is the software side — i want it to accept AZ/EL commands over serial so it plays nice with logging software, specifically i want to hook it into ham radio deluxe eventually but honestly even just being able to send a heading from a terminal would be enough for now.

has anyone written anything like this or know of a library that handles the rotator protocol stuff? i looked at the EA4TX interface but thats a whole separate thing i'd rather not buy if the arduino can just do it natively. also wondering if a pi would be better for this since then i could run a web interface from it and not need a pc at all to control it.

yeah actually i did almost exactly this about two years ago with a cheap yaesu clone rotator and an arduino uno. the protocol you want to look at is the Yaesu GS-232A/B format — its just plain ASCII over serial, things like "M180" to move to 180 degrees and "C2" to query position. really simple to implement, took me maybe an afternoon to write the parser once i understood the command structure. HRD and most other logging programs have that as an option in the rotator setup so you just point it at the COM port and it works.

the L298N should be fine for that motor as long as you're not pulling more than like 2A continuous, if the prop pitch is a bigger motor you might want something beefier. also make sure you put some flyback diodes across the motor terminals if the module doesnt already have them, learned that one the hard way when i fried a board.

on the pi question — honestly for just a rotator controller the arduino is cleaner because theres no boot time, it just works instantly when you power it on. i use a pi for my logging setup but i still have the arduino in between for anything that needs to be real time responsive. you could put both in the same box though and have the pi handle the web UI talking to the arduino over USB serial, thats what a few people on the groups.io list have done.

the GS232 thing is right, thats what you want. one thing i'll add — watch your pot coupling carefully, any slop in those gears and your position readback gets noisy and the software starts chasing its tail trying to hit a heading. i ended up averaging like 10 ADC samples and doing a small deadband, maybe 3 or 4 degrees, before the controller even tries to make a correction. made a huge difference in how it hunts.