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[SOLVED] Wiring RFD900x to 3DR Pixhawk Mini (4-pin telem port)

Here is an ultra-naive question, but my background is programming and I am a total electronics dummy.

I am using a 3DR Pixhawk Mini. The telemetry port accepts 4 pins. The SiK radios I have been using have 6 pins. The Mini comes with a cable that is 6-pin to 4-pin, where two of the pins are empty. Specifically, CTS and RTS outputs are just not used.

I have just received this RFD900x pair. The included telemetry cable ends with the typical 6-pin out. So can I simply cut and solder the 4 wires I need and ignore (seal) the ends of the unused wires? I think its an obvious yes, since I am just copying what was done for SiK-to-mini, but I could be overlooking something important.


You are correct in that you can just use the main 4 wires but I would most strongly suggest you do not power the radio from the FC.

With 1watt of output power and drawing ~800mA you will be really stretching the capability of the PixMini.
Much better to separately power the radio.

i suggest you power the module with a different power source…, and follow the correct pinout

Thanks @mboland and @Dave84. I am glad I asked. I have been planning to power with BEC from the beginning. However, I was just assuming that I would still use the cable the way I described above, limiting power to it from ardupilot params. Then power the module with a BEC. What I did not realize is that I should completely remove the power and ground wires when using an alternate source; I am really going from 6 to 2 3 wires!

Thanks again for the help!

it’s always suggested power the periphs with an alternate power surce.
Don’t forget that rfd are high performances so provide a good air flow

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Your signal wires require ground.
So it will be Rx-Tx-Gnd for the flight controller and Gnd-Vcc for the power supply.

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Thanks again! I have triple-checked the pinouts and should be ready to make the connection. My only concern is with Gnd for flight controller since it looks like it was removed here and here.

Update: got the radio setup and working fine. Took a while since I was still waiting on the BEC and marine connectors. Its for a boat, so I have to run wiring from inside the hull to the radio container on top. My only concern is heat, since it is enclosed in a pelican case. Field trials later this week; got to let the sealant where I cut into the pelican case set.

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