so ive been messing around with a raspberry pi zero w for the past few months trying to get it to handle some of the repetitive stuff in my shack - mainly automatic antenna switching based on band and logging contacts to a sqlite database without having to touch the keyboard every time i change bands. got it mostly working but i keep running into weird timing issues where the relay board doesnt always respond on the first command and i have to send it twice.

the relay board is one of those cheap 8-channel SainSmart things off amazon, running off 5v, and im controlling it through GPIO with a little python script. the zero is also pulling band data from my IC-7300 over USB using rigctld so maybe thats causing some kind of resource contention thing? idk. the zero only has that one USB port so everything is going through a hub.

anyway the actual antenna switching part works great when it works, i have a 4-square for 40m and a yagi for 20 and 15, so being able to just tell the pi what band im on and have it key the right relay is honestly kind of magical once it all clicks. just frustrated by the flaky relay response. wondering if anyone else has built something like this and whether i should just swap to an arduino mega for the actual relay control and keep the pi for the higher level logic stuff.

yeah the timing thing with those cheap relay boards is almost always a power issue in my experience. the pi zero really cant source enough current through its 5v pin to drive 8 relays reliably, especially if some of them are switching at the same time. i ran into the exact same problem on a band decoder project last year. ended up just powering the relay board from a separate 5v supply and tying the grounds together and the flakiness went away almost completely.

the arduino idea isnt bad either honestly. i actually do something similar to what youre describing - pi handles all the logic, networking, logging, the rigctld stuff - and an uno just sits there as a dumb relay controller that listens for simple serial commands. keeps the timing stuff deterministic and the pi doesnt have to worry about any of that. you can hot-reload your python on the pi without worrying about screwing up the relay state too which is nice.

I did something kind of similar a while back for my contest station, though mine was a lot simpler - just used an Arduino Nano to read the band voltage output from my radio (the kind some rigs put out on an accessory connector) and switch a BCD relay board. no pi involved, kept it dead simple on purpose because contest weekend is not when you want to be debugging software lol.

that said the pi approach sounds more flexible. whats your latency like between changing bands on the radio and the antenna actually switching? thats the thing that would bug me personally, even a half second delay feels weird when youre moving around a lot.