R/C channel passthrough to unused PWM outputs

Is it possible to implement R/C channel passthrough to PWM outputs that aren’t in use on the selected airframe? My specific planned use case goes like this:

  • Pixracer
  • 16ch SBUS R/C input (FrSky X4R-SB)
  • Quad airframe (PWM 5 and 6 unused)
  • Separate gimbal (Feiyutech Mini-3D) that takes PWM input for operating mode and camera pitch

What I would like to do is use PWM 5 and 6 outputs of the Pixracer to control mode and camera pitch on the gimbal, using two RC channels not mapped to any PX4 function. Essentially this makes the Pixracer additionally function like an SBUS-to-PWM decoder.

If it’s possible to make a configuration like this already, I’d much appreciate a hint where I need to look - a search of the existing documentation didn’t reveal much, though maybe I’m not thorough enough. If not, could such a feature be implemented?

I’m interested in doing something similar. I don’t have my pixracer yet, but have been looking at the settings in preparation.
So, here is a list of parameters:
and look at “RC_MAP_AUX#” and that might point you in the correct direction.
It mentions what the default function of the “aux” channels does, but I don’t know how to define an alternate function.

–edited to say I think I’m wrong, but will leave this just in case it helps… But I guess what I mentioned is assigning an RC channel to a different PIN that isn’t available on the pixracer, and not to one of the existing RC pins… I suppose we should wait for someone experienced to answer.

I need exactly the same setup as @olex mentioned. Could any PX4 developer give us any hint/advice, please? Pixracer does not have any AUX pins. Parameter RC_MAP_AUX# is related to physical AUX pin only but I could be wrong.

Ich habe die gleiche Frage, da mein Pixfalcon auch keinen AUX Ausgang besitzt.
Danke für euer Feedback.

I’ll add a mixer for 5 and 6 to the Quad configs - you can then use those for roll / pitch of a gimbal.


Great news @LorenzMeier :slightly_smiling:. Can’t wait for this new feature. Any date?

Hi @LorenzMeier, any news regarding your declaration?



Any news on this functionality?
Is this available?
Is there an ETA?

Is that what this is doing?

I see group 3 index 5 and 6, but I don’t understand how this maps to an output on either the pixracer or the pixfalcon. If this maps something to motor output 5 and 6 for quad x frames doesn’t appear to be working in the current stable release that qground control loaded onto my pixfalcon.

Hi Lorenz, is this functionality still in the roadmap? It would be really appreciable!

Hello all,
I expect this document (http://ardupilot.org/copter/docs/common-rcoutput-mapping.html) might be helpful to you. It describes how one might remap channels on the Pixracer, Pixfalcon or other similar board to a desired function. This page (https://github.com/ArduPilot/ardupilot/blob/master/libraries/SRV_Channel/SRV_Channel.h#L40) contains some info on your exact remapping options.
Hope this helps!

this is for Arducopter only, no?