My Matek F405-CTR flight controller running Arduplane was previously connected to a bluetooth stick ; I disconnected this and connected the FC to TXO and RXI of the Arduino Pro Mini ( I left same settings 57600 for the serial1 port in Mission Planner )
By grounding D2 of the Pro Mini I set the output of the translator to be Sport rather than SBUS
And finally I connected the output pin of the translator , D5 , firstly to a Frsky Receiver's Sport with not much success, and then to directly to the back of my 9x radio, to the lowest pin of the module bay, with good success.
So, no module and no Rx involved , no 2.4GHz frsky link , as user LTMNO explained here.
In er9x I switched my Protocol from MPM to XJT , even though none of them are in, so that the expected Baud rate would be 57600
In telemetry I was able to successfully select ArduP (or Frsky as well ).
With this ArduP I get the extra graphical screen as expected.
The status 'No Data' went away and gets replaced with 'Disarmed' which is a good sign.
I am seeing the magnetic bearing react accordingly whenever I move the flight controller on the table.
The altitude and GPS coords seem OK.
About GPS info on the left, I do not understand why my ArduP screen says 'No GPS' at the same time as sat 3 and hdop 11.1
Before and after, the Mission Planner on the laptop was showing '3D fix' and no red warning about 'No GPS'.
I learned about this :
I did not see many people reporting about ArduP with a 9x + er9x;
Fardenco on his 9x with er9x was using HubRaw , so he was not using/seeing this extra screen.
Other people where showing '3D fix' on their 9XRPro screens and ersky9x ; I suspect that for this portion, the code is common to er9x /ersky9x.
I did not see anyone really mention 'NoGPS' , so I must be doing something wrong...
Any Idea ?
I have since toasted my Arduino in the subsequent connexions but no big deal, I am going to order a few more replacements, as this APM Mavlink2Frsky is great Thank you Mike, for making it available to the community!