so ive been messing around with this for a few weeks now and i think im finally getting somewhere. basically what i wanted was something that would automatically log contacts to cloudlog whenever i key up, pull from my IC-7300's CI-V interface, and also flip a relay to cut power to my amp if the SWR spikes past a threshold i set. seemed simple enough on paper.

the pi zero W is handling the serial comms fine, i got pyserial talking to the radio no problem, and i can read frequency, mode, all that. the relay part is working too — just a little 5v relay board from amazon wired to GPIO 17, nothing fancy. the issue im running into is timing. like if i poll the radio too fast it seems to confuse the CI-V and i get garbage back sometimes. slowing the poll down to like 500ms helps but then theres a lag before the relay trips which kind of defeats the purpose for the SWR protection thing.

also tried doing it with an arduino nano first but keeping a wifi connection stable on an arduino is kind of a pain unless you throw an ESP8266 at it, which then becomes its own project. the pi just makes more sense for anything that needs to talk to the internet i think. anyway curious if anyone else has gone down this rabbit hole and whether there's a smarter way to handle the polling timing issue.

yeah the CI-V polling thing is a known headache. icom's baud rate on that interface is not super forgiving and if you're hammering it you'll get collisions especially if the radio itself is trying to send unsolicited data at the same time. what helped me was setting the radio to push mode if your firmware supports it — basically the 7300 can be configured to broadcast its status changes instead of waiting to be asked, which takes all the timing pressure off your polling loop. check the CI-V settings in the menu, theres an option for it. then your pi just sits and listens instead of constantly asking.

for the SWR protection i'd honestly separate that out onto a dedicated arduino or even just a standalone comparator circuit. a pi running linux is not really a real time system, theres always gonna be some scheduler jitter that could bite you if you need sub-100ms response times. an arduino will react way faster for anything that's safety-critical like cutting power to an amp. i run a similar setup here, pi does all the logging and network stuff, tiny nano watches the SWR via an AD8307 and trips the relay itself without waiting for anyone's permission.

dont overthink the timing thing too much honestly, 500ms is probably fine for logging purposes and if your SWR is spiking so fast that half a second matters you've probably got bigger problems anyway lol. but yeah the split approach the other guy mentioned is smart, pi for the brains and a little microcontroller for anything where timing actually matters. i did something similar with a wemos D1 mini watching my tuner and it works great, just sends a udp packet to the pi when something goes wrong and the pi handles the logging and notifications. cheap and it actually works reliably which is more than i can say for some of my more ambitious projects