so ive been messing around with a pi 4 i had sitting in a drawer and i got direwolf running on it last week, got it connected to my kenwood TM-V71A through a cheap sabrent usb audio interface. its actually working as an igate now which is kind of cool but i want to take it further.

the thing is i want to add some automation to it — like have it monitor a few frequencies and maybe trigger some relay outputs based on certain conditions. i was thinking of wiring up an arduino uno to the pi over serial and using the arduino to handle the actual GPIO switching so i dont have to worry about the pi's 3.3v pins doing something dumb to my radio equipment. anyone done something like this or am i overcomplicating it.

also the audio levels going into direwolf are kind of all over the place, not sure if its the soundcard or the cable i made. using a standard 6-pin mini din to 3.5mm setup, nothing fancy.

yeah the arduino as a buffer between the pi and anything RF-adjacent is honestly the right call, i burned a pi zero doing exactly what you're trying to avoid. the 3.3v GPIO pins on those things have basically no protection and if you get any transient from the radio side youre just toast.

for the audio levels in direwolf there's a section in the config file where you can set ADEVICE and then tune the input gain — but honestly the sabrent cards are kind of hit or miss for this. i swapped mine out for a cheap CM108-based dongle and the decode rate went up noticeably. direwolf has a built in audio level monitor you can run from the command line, just do direwolf -t 0 and watch what it shows you before you start chasing hardware problems.

what are you planning to trigger with the relays btw, like antenna switching or something else entirely

i run almost the exact same setup but i skipped the arduino and just used an optoisolator board i got off amazon for like 6 bucks, 4 channel thing, goes between the pi GPIO and whatever im switching. works fine for PTT control anyway. might not be enough if youre doing something more complex but for basic relay stuff its hard to beat.

one thing that bit me with direwolf and the V71A specifically — make sure you have the DATA BAND set correctly on the radio, mine was defaulting to band A and my antenna was on band B and i spent like two hours wondering why decode rates were garbage before i caught it