Autotune - 6 Channel Receiver

I’m having trouble being able to access the Channel 7 or Channel 8 AutoTune function as I have a 6 Channel receiver connected to APM 2.5.2 via PPM. I’m not using Channel 6 and have tried playing around with the RC6_FUNCTION/RCPassThru option but its’ correct use escapes me. The transmitter I’m using is a DX8 and the receiver is an OrangeRX 615X.

I guess that I could always dump PPM and hard-wire all the receiver channels to APM with the exception of running 6 from the receiver to either 7 or 8 on APM but that defeats the advantage of using PPM.

Any suggestions or guidance will be appreciated.

I can’t immediately think of a way that you could change the use of ch6 through a configuration change. We have RCMAP but it only controls the mapping of the first four inputs (roll, pitch, yaw, throttle). I think that means you’re stuck with having to do a wiring change.


you use PPM. Van you switch to “traditional”?
if so, you could use the wires to “fake” channel 7

other option… why use channel 7?
In the Missiio planner software you can (as far as I can recall) assign another channel?


Same here, 6 channel receiver in PPM.

@rmackay9 - Isn’t AutoTune just another flight mode? If so, why can’t I just assign my flight modes such as:

  • stabilize
  • AltHold
  • AutoTune

If not, anything to prevent me to send channel7 commands from dronekit? Or equivalent, send a “rc 7 1999” from mavproxy.

Yes, you’re right. As of Copter-3.3, AutoTune is just another flight mode so you can set it up on the channel 5 flight mode switch.
I suspect that dronekit doesn’t have the mapping of the flight mode number (“15”) to the name “AutoTune” so it’s set-mode might not work but I’m not sure. The setting of rc 7 using mavproxy should work. I think MAVProxy also has the mapping of the flight mode number to the name so “set mode AUTOTUNE” should work… I think.


You need a flight mode of AltHold in order for AutoTune to work.

You can set AutoTune to activate when assigned Ch7 or Ch8 switch/ POT is at a high value if Ch6 is not available.

@rmackay9 @pmshop - I’m confused I hear two different messages.

No confusion.
Rmackay is incorrect with his statement.
You need AltHold as a flight mode.
Then you need AutoTune as an operation.
BOTH are required for the process.
You cannot have two flight modes working at the same time with the traditional 3 position and 2 position flight mode setup.
This will clear it up: (and I was taught not to pay attention to the AutoTRIM process. A good accelerometer calibration does not require AutoTRIM)

rmacky is absolutely correct for versions 3.3 and above as he stated. I have been using this method myself on a three position switch. The first position is stabilize, the second is alt hold, and the third is autotune. It works exactly as expected passing to autotune from alt hold.

I do wish there was more freedom on the channel 6 assignment possibilities though.

You need AltHold as a flight mode.
Then you need to switch on AutoTune.
With your method, the moment you switch to AutoTune, you disengage AltHold which is required.

Required in what sense? For the AutoTune process to start? For the AutoTune process to run smoother than otherwise?

you need to hold the altitude to perform the AutoTune like the video I posted says.
So you need two different functions. AltHold from the 6 pos switch and from everyone I spoke with, set a POT to AutoTune.

Set altitude at 25 feet and trigger AutoTune - watch the dance.

The moment I switch to autotune it properly begins the autotune procedure. In 3.3 and above the flight controller engages the autotune process and operates properly when switching from alt hold to autotune as a flight mode.

I have used this process repeatedly so I am pretty sure it works.


So what keeps it at the proper continuous altitude which is part of the procedure?
Because if the altitude changes you are not getting an accurate AutoTune.
And pardon my error on my original chime in.
I meant to say I was taught to stay away from AutoTrim.
A good accelerometer calibration will not need AutoTrim.

I suspect they added the alt hold to be automatically enabled when selecting autotune using the flight mode selection. And it does work quite well this way.


What is the final solution , can i use auto tune an 6 pos switch , or. Channel 7 , ardupilot v 3.2.1 apm 2.8 flysky 6 channel rec.