so ive been messing around with a raspberry pi zero w for the past few weeks trying to get it to handle some basic shack automation stuff and honestly it's been a rabbit hole i did not expect. started out just wanting it to log my contacts automatically from my IC-7300 via the USB connection and maybe flip a few relays for antenna switching but now im knee deep in python scripts and i cant stop adding features to the thing.

right now i have it pulling band data from the radio over CI-V, deciding which antenna to connect based on what band im on, and logging to an sqlite database that syncs to ADIF every hour or so. also added a little 2x16 LCD so i can see basic status without having to look at the computer. the whole thing runs headless and just comes up when i power on the shack strip.

my question is more about the antenna switching side - im using a 74HC595 shift register to drive 8 relays through only 3 GPIO pins which works great on the bench but i keep seeing weird behavior when i key up. wondering if anyone else has seen relay chatter or logic glitches from RF getting into the GPIO lines. i added some bypass caps but not sure if thats enough or if i need proper optoisolation between the pi and the relay board.

yeah RF into GPIO is a real thing and bypass caps alone probably wont cut it if youre running any kind of power. i had almost the exact same problem with an arduino mega i was using for a band decoder a couple years back - the thing would just go crazy when i hit the key on 40m. ended up putting optocouplers on every single control line between the arduino and the relays and that fixed it completely. the PC817 is cheap and works fine for this, you can get a bag of 50 for almost nothing.

also make sure your relay board has its own separate power supply and that the grounds are only connected at one point or you can get ground loops that make everything worse. ferrite beads on the data lines going to the shift register helped me too, just snapped a few on the wires and it cleaned things up noticeably.

i did something similar but with a full pi 4 because i wanted to also run js8call and wsjt-x in the background. probably overkill but whatever i had it sitting around. the antenna switching thing i just punted on and bought one of those cheap 8 port HF antenna switches that takes BCD input, ran that from the GPIO directly with just some 1k resistors in series and honestly havent had any RF issues but im only running 100w so maybe thats why. higher power id definitely look at isolation more carefully like the other guy said.