Pixhawk 4 + Frsky R9 MM or R9 Slim+

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1

Hi all

I’m planning platform based to Pixhawk 4 by Holybro and Frsky R9 MM or R9 Slim+ as receiver. Do you think that combination will work fine ? Also telemetry? Other alternative would be Dji Naza v2 platform, but it is outdated. Ideal situation is to found a robust platform.

2

did a quick google and found this…

It looks promising

https://docs.px4.io/en/peripherals/frsky_telemetry.html

3

Nice link with all the info you will need. One thing to point out is that the R9 mm outputs inverted smart port telemetry (which is actually normal uart)… the short of it is that I think you can just hook it up directly to a spare UART and you are good to go. No need for a special cable since the signal does not need to be inverted. I have not tried telemetry bon an R9 mm yet with pixhawk but it should work like this.

4

Hi. I know this is quite an old topic, so fingers crossed!

I too would like to connect an FrSky R9 MM Inverted S.Port, to the TELEM2 port on a Pixhawk 4 controller.

I understand that in half duplex (S.Port) the same pin is used for both Tx and Rx functions, however I have not been able to find whether I should connect to the TX(out) Pin 2, or RX(in) Pin 3 of the TELEM 2 port.

Please can anyone point me to the relevant documentation?

Also, just out of interest, could someone explain how the data direction is negotiated / controlled?

Thanks in advance for any help

Alan K.

Pixhawk to FrSky R9MM
Pixhawk to FrSky R9MM1162×633 18.4 KB

5

Yes essentially you are correct assuming you are using an h7/F7 based Autopilot board.

More info is here Connecting to FrSky Sport and FPort — Plane documentation

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image1080×875 103 KB

6

Thank you for your prompt and informative reply, Alex.

I am using Pixhawk 4 which is based on the STM32F765 processor and Q Ground Control for setting parameters.

Q Ground Control, does not appear to offer the range of parameters listed in the links which you provided. Instead it offers a single parameter “TEL_FRSKY_CONFIG” to which can be assigned a telemetry port (TELEM2).

The instructions are…

Configure the serial port on which FrSky will run using TEL_FRSKY_CONFIG.
There is no need to set the baud rate for the port, as this is configured by the driver.

What am I missing? :thinking:

Thanks again A.K.