I recently obtained an Armattan Gecko 4 inch quad frame. I wanted to build it with an AUW less than 250g, which is a challenge. I decided to use a Diatone Mamba mini stack to keep both cost and weight down. The rest of the build is Brother Hobby Avenger 1507/2800kV motors, A FrSky XSR-E receiver, a Caddx freestyle camera, and an AKK FX3 VTX. With a Tattu 4S 650mAh LiPo the AUW is just under 250g, but I'll probably fly it with a 4S 850mAh LiPo.
The Mamba mini is an F4 FC equipped with only 3 UARTs. I wanted to use SBUS for the receiver, smart audio for control of the VTX, and Smartport for the telemetry back to the Taranis transmitter. The Mamba only has an inverter on UART1 to service SBUS. I tried to get Smartport working on TX1 and TX6 with soft serial, but it doesn't appear to be implemented on the Mamba. The only option was to use the Smartport inverter -- I set it up on UART6, using VDD = 5V with no issues.
The telemetry settings:
tlm_inverted = OFF
set tlm_halfduplex = OFF
There is still a need for this inverter when using some F4 flight controllers like the Mamba. I have not yet migrated to F7 flight controllers -- they are a lot more money and the F4 FCs still work pretty well.