Ok, I have searched high and low all over the internet for an answer to this and have tried everything I found. This is my first quad build so I’m sure that has something to do with this but for some reason I can’t figure it out. My Eachine tx5258 VTX works well and has a strong signal running through my mamba f405 flight controller to my camera and I get great video, but when I solder the smart audio to the tx1 tx3 or tx6 pads the vtx still refuses to connect in beta flight, yes I did click save and reboot. The smart audio function also works well on everything else besides the vtx in my goggles. I can change and manipulate things in there but when I go to VTX it’s as if I have no vtx connected. It also is telling me the same thing in beta flight also. I’m not sure if my vtx is somehow broken or I somehow missed something on how you need to set it up but this is so frustrating. If anyone has ever had this problem or could help me out I would really appreciate it.
Make sure you are going from the FC TX pin to a RX pin on the VTX and from a TX pin on the VTX to an RX pin on the FC, know this is confusing but with UART you go TX->RX and RX->TX should never be RX->RX or TX->TX (well shouldn't say never because some people label it this way but for UART pretty standard to do TX->RX and vice versa)
I actually did manage to find a previous video on how to solder the vtx to the fc and it did explain that so that wasn’t the problem. As for the RX wire I don’t think VTX’s have those, at least I don’t think my 5258 does anyways. From the research I tried to do the SA wire should be connected to a TX pad the video wire should be on video out and the VTX should be powered from VCC if it can handle it. Is that the correct wiring for this VTX?
Cool yah just something easy to overlook or do wrong if didn't follow some guide but that sounds right just sending control signals from the FC to the vtx so should be using a TX pad on the FC. Also yes in general sounds fine, whenever you have some communication between two things you usually want common GND as well for the reference voltage so when one device is pulsing 5V or 3.3V on a line the other can "see" when it is getting above say half that voltage to count it as a pulse... Tldr if the vtx doesn't have common GND with FC or isn't getting GND off FC that can effect signals but sounds fine with regard to that.
Personally always buy vtx with little 1 character LCD display and single button for setting the frequency and power output. The smart audio hook up is kind of nice I guess if switching a lot but I'm pretty much on R1 all the time.
Good to hear have that backup option still to control it like a caveman with a stick if need be
One other thing maybe worth mentioning is that the pinout that the ports tab is going to map to essentially is baked into the firmware based on what was flashed to the FC, so if you flashed it yourself you may want to just triple check that you selected the correct board variant. If it turns out you need to flash again make sure to look up how to get a dump of everything and restore, if staying on the same version but just switching board types should be pretty safe to get the diff of your changes and reapply them (or can just setup fresh if already remember most of the things that need to be done). When you connect FC to betaflight you'll see the current version/board selection that is flashed in the log/status window near the top (hit expand or more button whatever it is to see a few lines of the log and scroll back to see when you hit connect button what the FC reported as make sure it matches the actual board/what MFG says to select there for flashing).