so ive been messing around with an arduino uno for the past few weeks trying to get it to handle my antenna switching automatically based on what band the radio is on. the idea is pretty simple — read the band data output from my IC-7300 (its on the accessory port, CI-V stuff) and then fire the appropriate relay to connect whichever antenna is right for that band. got the relay board wired up and the basic sketch is working for manually triggering the relays but im stuck on parsing the CI-V data coming in over the serial connection.

ive read through the icom protocol docs and i kind of understand the structure of the messages but the arduino keeps reading garbage. not sure if its a baud rate thing or im just not handling the byte stream correctly. running at 19200 right now which i think is the default for the 7300 but honestly not 100% sure. anyone done something like this or have a sketch they started from? dont want to reinvent the wheel if someone already figured out the CI-V parsing part.

yeah i did almost exactly this a couple years back with a 7300 and a raspberry pi actually, not arduino, but same idea. the CI-V parsing isnt that bad once you understand that every message starts with 0xFE 0xFE and ends with 0xFD — you just watch for those delimiters and buffer everything in between. the baud rate on the 7300 i had set to auto and that caused me all kinds of headaches, just set it to a fixed rate in the radio menu and match it on the arduino side. 19200 should be fine.

one thing that bit me was the CI-V address — the 7300 default is 0x94 i think, double check that yours matches what youre sending in your query command otherwise the radio just ignores you. also make sure youre actually in transceive mode or polling, the radio wont just spit out band data continuously unless you tell it to or have transceive enabled. i can dig up my old python code if you want a reference even if its not arduino it might help you understand the flow.

CI-V on arduino is totally doable, i use a nano for my shack automation and have it talking to a kenwood but same general idea. one gotcha — make sure youre using SoftwareSerial for the CI-V side and keeping hardware serial free for debugging, otherwise you cant see whats happening and troubleshooting is a nightmare. just a tip that saved me a ton of time early on.