so ive been messing around with this idea for a while now and finally started actually building it. the basic concept is that i want the arduino to read the band data output from my IC-7300 and then trigger the appropriate relay to switch between my HF antennas automatically. the 7300 puts out CI-V over USB so im reading that with a small python script on a raspberry pi zero W, and then the pi sends serial commands to the arduino which controls the relays.

it mostly works but the timing is kind of janky — like if i spin the VFO fast through multiple bands the relay clicks like crazy and sometimes ends up in the wrong position. im thinking i need to add some kind of debounce delay in the python side but not sure if thats the right approach or if theres a smarter way to do it. also using a 4-relay module i grabbed off amazon, nothing fancy, probably SRD-05VDC-SL-C relays if i had to guess.

anyone gone down this road before? curious if theres existing software for this kind of thing or if im just reinventing the wheel here

yeah i did something similar last year with a 7600 and a pi 3B+. the debounce thing is exactly your problem, what i ended up doing was just adding a short timer on the python side — basically dont actually trigger the relay until the band has been stable for like 300ms or so. if a new CI-V packet comes in during that window you just reset the timer. works pretty well in practice, spinning the VFO fast doesnt cause the relays to go nuts anymore.

the other thing i ran into was the relay module itself pulling enough current that it was browning out the pi when multiple relays fired at once. ended up powering the relay module from a seperate 5v supply instead of off the pi's GPIO pins. might not be your issue but worth checking if you see any weird resets.

not sure if this helps but there's a guy on github who wrote a whole band decoder specifically for icom radios with CI-V, think the project is called something like ic-band-decoder or similar. i used chunks of his code for my station and it saved me a ton of headaches. handles the debounce and has support for a bunch of different relay configurations. might be worth a search before you go too deep into rolling your own.