so ive been messing around with an arduino mega for the past few weeks trying to get it to auto-switch my antenna relays based on what band my radio is on. the radio puts out band data on a DB9 connector (its an icom 7300 so the CI-V bus is an option too but i went the simpler route first) and the idea is to just have the arduino read those lines and then key the right relay to connect whichever antenna is appropriate.

its actually mostly working now but ive hit this weird issue where if i switch bands really fast on the rig the relay sometimes clicks to the wrong position for like half a second before correcting itself. not sure if thats a debounce thing in the code or if the band data lines are just noisy. i added a 50ms delay before acting on the band change and it seems better but feels hacky. anyone else done something like this and found a cleaner way to handle it?

also thinking about eventually tying a raspberry pi into this so i could do logging and maybe run flrig or something, not totally sure what the architecture would look like yet. open to ideas.

yeah i did basically the same thing with a 7600 a while back. the band data lines on icom rigs can be a little glitchy during the transition, the decoder in the radio doesnt always settle instantly. 50ms is actually in the right ballpark honestly, i was using something like 75ms and it was rock solid. you could try reading the band data twice with a short gap and only acting if both reads agree, thats a more proper debounce approach than just a flat delay. cleaner in the logic even if it ends up being similar in practice.

on the pi side of things — if you go that route i'd keep the arduino doing all the real-time relay control and just have it report status to the pi over serial or USB. the pi running linux is just not great for anything where timing actually matters, too many other things going on in the OS. but for logging, running hamlib, flrig, wsjtx whatever, its perfect. i have a pi 4 on my desk that basically runs my whole digital station and its been solid for over a year now.

curious what relays you're using for this, i've been wanting to do something similar but worried about switching speed and whether a regular relay can even keep up if you're band-hopping during a contest. figured solid state might be better but they get expensive fast depending on the power level