so i've been slowly turning my shack into something that would probably look insane to anyone who walked in cold. started about 8 months ago with just wanting the pi to pull spotting data from the cluster and display it on a little screen near the rig, simple enough right. well now i've got a pi zero W running hamlib over a USB serial adapter to control my 7300, a second pi 4 running a full logging setup with cloudlog, and an arduino mega in the middle of all of it handling antenna switching based on band changes from the radio.

the arduino part is where it gets interesting and also where i keep running into weird timing issues. basically i'm reading the band data output from the 7300 via hamlib, sending that over to the arduino on a serial connection, and then the arduino is driving a set of relays for my homebrew antenna switch. works great probably 90% of the time but sometimes on rapid QSY it'll just... not switch. or it'll switch to the wrong antenna and then correct itself a second later. i dont think its a hamlib polling speed thing because ive bumped up the poll rate and it didnt really help. wondering if its something in my arduino code where im not debouncing or waiting long enough before acting on the new band data.

anyone doing something similar or have thoughts on the timing side of this? im not a software guy by trade so my code is probably embarrassingly bad but it works mostly

yeah the timing thing is almost definitely your issue, hamlib polling is kind of inherently laggy depending on the rig and the baud rate your talking to it over. what i did when i built something similar for a different rig was add a short confirmation delay on the arduino side - basically dont act on a new band value until you've seen the same value come in like 3 or 4 times in a row. adds maybe 300-400ms of total latency before the switch fires but you stop getting those phantom switches from transient data. its a poor mans debounce but it works fine for antenna switching where a fraction of a second doesnt really matter.

also worth checking if your serial buffer is getting overrun on the arduino side, especially if you're sending data continuously from the pi. ive had cases where the buffer fills up and you start reading partial packets and the arduino just does whatever it wants with the garbage data.

i went down basically the exact same hole last winter. ended up ripping out the arduino middleman entirely and just driving the relay board straight from the pi GPIO pins with a simple python script. one less thing to go wrong honestly. the only reason i kept the arduino originally was because i thought i needed the real-time reliability but for antenna switching the pi is plenty fast enough and you get way more flexibility with the logic on the python side. just something to consider if you keep fighting the serial comms between the two boards, sometimes simplifying the architecture is easier than debugging the bridge