No telemetry from Matek F405-Wing with X8R

[rsilk49]

I have installed the latest Arduplane beta 4 on the F405-Wing. Arduplane 4 has new serial parameters to configure UARTs for Frsky telemetry. I have ersky9x-pa4r222 installed on the radio.

Previously with a Pixhawk and C&T adapter cable this was working well using SERIAL5_PROTOCOL 10 on Arducopter 3.9 using Frsky X8R receiver, and XJT module.

Now I am setting up a Matek F405-Wing with the same radio, receiver and module.
As per the Matek Arduplane web site I have configured
SERIAL6_BAUD 57
SERIAL6_PROTOCOL 4
SERIAL6_OPTIONS 7

I have a single pin cable connecting the S-port signal pin on the X8R to T6 pin on the FC.

I have also tried a 3 wire cable between the receiver and the FC, and PROTOCOL 10 (passthrough).

The only telemetry data I see are from the receiver itself, i.e. RxV and RSSI, not FasV etc. TmOK only shows "1" which if I remember should be "2".The telemetry configuration for the F405 on the radio is the same as for the Pixhawk model.

[rsilk49]

Turns out that the F405-Wing running Ardupilot cannot handle inverted Smartport telemetry from the X8R.

So 2 options:
1) telemetry adapter cable e.g. C&T
2) use a receiver that can provide a non-inverted Smartport signal -- either by design or soldering a wire to a pad or existing joint on the receiver circuit board. e.g. R-XSR.
Howto : https://oscarliang.com/uninverted-sbus- ... receivers/