Hello everyone I found that smart-audio does not work with any settings. I’ve probably tried everything I can. Everything works fine on INAV as always. What could be the reason?
Here are my settings:
Serial:
SERIAL5_BAUD 4
SERIAL5_OPTIONS 4
SERIAL5_PROTOCOL 37
VTX:
VTX_BAND 5
VTX_CHANNEL 3
VTX_ENABLE 1
VTX_MAX_POWER 800
VTX_OPTIONS 3
VTX_POWER 800
I trying set serial option TX_PullDown, but is not working. Help me please! 
I’m having problems with SmartAudio on a Rush Ultimate Plus that is supposed to be using a TBS-licensed SmartAudio implementation.
From what has been said previously, Ardupilot is much less tolerant of protocol violations in its SmartAudio implementation than INAV/Betaflight is, and some manufacturers have sloppy implementations.
That said, I’m a bit suspicious of the Ardupilot implementation given that (in my case) RushFPV licensed SmartAudio from TBS and that’s supposed to mean TBS does validation of the hardware to make sure it’s working properly.
I know this is bringing back a dead thread, but it was where I started so here is my successful update.
I managed to figure out the special combination of things to get an OpenVTX OVX306 working with smart audio on a SpeedyBee F405 v3.
SERIAL1_BAUD,115
SERIAL1_OPTIONS,0
SERIAL1_PROTOCOL,37
VTX_ENABLE,1
VTX_BAND,4
VTX_CHANNEL,2
VTX_MAX_POWER,400
Maybe disable the CRC check in the VTX options if nothing else is working.
VTX_OPTIONS,0
VTX_POWER,25
If the frequency shows up, then it’s connected
VTX_FREQ,5732
The flashes on the VTX indicate