so ive been messing around with a raspberry pi zero w for the past few weeks trying to get it to control a few things in the shack automatically and i think im finally getting somewhere but wanted to see if anyone else has gone down this rabbit hole before i invest more time into it

basically what im trying to do is have the pi monitor my rig's CAT interface and then trigger a relay board based on what band i switch to - like automatically switching my antenna relay from the 40m dipole to the vertical when i go to 20m, that kind of thing. i got a cheap 4-channel relay module off amazon and the GPIO stuff is pretty straightforward but im running into weirdness where the relays are chattering when i first power up the pi and i dont know if thats a software timing issue or if i need pull-down resistors or what

also side question - anyone mixed arduino and pi in the same project? was thinking the arduino might be better for the actual relay control since its more deterministic than linux running on the pi, the pi would just handle the CAT parsing and then send simple serial commands to the nano. does that make sense or am i overcomplicating it

yeah the chatter on power-up is almost certainly the GPIO pins floating before your python script initializes them. you want to set your relay pins as outputs and drive them HIGH (or LOW depending on your module - most of those cheap relay boards are active LOW which trips people up) right at the start of your script before anything else happens. you can also add a small RC filter on the control line but honestly just sorting the GPIO init order usually fixes it

and the arduino/pi split is exactly how i do mine actually. pi handles all the heavy lifting - parsing the IC-7300 CI-V traffic, running a little flask server so i can see band info on a webpage in the shack, all that stuff. then it just shoots a single byte over serial to a nano every time the band changes and the nano does the actual relay switching. way more reliable than trusting linux timing for anything that needs to happen in under a few milliseconds. only downside is you got two things to power and debug instead of one but its worth it imo

i did something simmilar last year but i went all-arduino, no pi involved. just an uno reading serial from the radio and switching relays. works fine but adding any kind of logging or network stuff gets painful fast on an arduino. so yeah your idea of splitting the jobs actually sounds smarter than what i did honestly

one thing to watch - those relay modules from amazon can inject noise back into your supply if youre not careful, i had some weird audio hum issues that took me forever to track down and it turned out to be the relay coils. slapping a diode across each coil helped or you can just use an opto-isolated relay board which costs like two dollars more and saves you the headache