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PPM mixed up channels

Posted by Tim Johnston on September 29, 2013 at 5:32am

I wondered if anyone could enlighten me what is going on here.

When I plug in my APM 2.5, 3.01 to my Rx using PPM the channels are mixed up... ie the Throttle =Roll,

Yaw=Yaw, Pitch=Throttle, Ail=Pitch  the switches are fine.

Everything works the way it should when plugged in PWM, the channel mixup only happens when using (trying to use ) PPM.

I have reloaded PPM encoder firmware, used different TXs and Rxs etc to no avail.( same thing happens)

Tx radios I have are Graupner Mc32 and Jr 9x with dragon link V2

I fly Mode 2. 

Thanks in advance.

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Replies

  • Darryl Zubot January 11, 2015 at 9:25pm

    I had to remap my channels with my DX8 and dragon link with pixhawk.  Throttle was the only one that needed swapping. My Channel setup on the dragon link to ppm encoder are 3,1,2,4,5,6,7,8. But with my setup I cannot get the remote to change the flight mode even when the software says the switch is working for it, only way is by using APM planner software and 3dr radios to change flight modes, the spektrum remote will not change modes when I use the appropriate switch to change it. Is this normal with pixhawk?

  • Steve Gebler July 14, 2014 at 8:53am

    Here is the solution to the channel mapping issues having to do with moving the PPM signal from the DragonLink to the Pixhawk or other APM based flight controller.

    In the full parameter list of APM Planner 2, look for RCMAP.  Therein lies the Pitch, Roll, Throttle, and Yaw Configuration.
    By changing to these parameters, all is right with the world.
    RCMAP_Pitch 3
    RCMAP_Roll 2
    RCPAMP_Throttle 1
    RCMAP_Yaw 4

    APM Planner 2.0ScreenSnapz002.png

    • Developer
      Bill Bonney > Steve Gebler July 14, 2014 at 11:31am

      If you remap channels on the APM2.5/6 and using PPM please bypass the PPM encoder, otherwise failsafe will work incorrectly

      see http://plane.ardupilot.com/wiki/arduplane-parameters/#RCMAP__Parame...

      see http://copter.ardupilot.com/wiki/common-apm25-and-26-overview/#Expl... on how to bypass the onboard PPM encoder

      • Carlos Calvetti > Bill Bonney March 25, 2015 at 4:31pm

        Hello Bill,

        Would you be able to help me out? I have a similar problem. I set up my DL with my DX8 and Pixhawk and my channels are reversed... Right is left, up is down and so on... I could not reverse the channels on the DX8 since it wont do it on the slave mode.I finally did it on Mission Planner but the other i lost control completely and it looks like i was trying to bring the copter back but MP was reading on reverse...

        My channels are set this way:

        Ch1=Ch2

        Ch2=Ch3

        Ch3= Ch1

        Ch4=Ch4

        Please help!!

        45.BIN

        https://storage.ning.com/topology/rest/1.0/file/get/3702691024?profile=original
      • Mauricio > Bill Bonney September 15, 2014 at 7:54am

        I had the same problem with pixhawk, trying to connect to a Dragonlink receiver. I had to remap as follows:

        - Pitch 3

        - Roll 2

        - Throttle 1

        - Yaw 4

        and had to assign a different switch to the flight modes on the DX8, so I can see now during RC calibration on Mission Planner each channel now corresponds to the right stick, so all good up to there.

        But now when not in RC calibration I have no servo movement and I have Failsafe on Flight Data window, you are right Bill ion that Failsafe won't work correctly. When I turn off my DX8 the failsafe goes away.

        I'm sure failsafe needs to be set differently, everything else seems to be fine.

        I read the links but really doesn't explain how to set failsafe for pixhawk when using PPM after remapping the channels.

        Any detailed explanation will be highly appreciated!!

        • Andrew John Britton > Mauricio September 28, 2014 at 4:51am

          Exactly the same problem here after remapping the channels it appears that the failsafe is reversed i.e when i activate failsafe (995 on channel 1 remap for throttle) the pixhawk behaves as if it has a good throttle signal and is ready for flight if i go above the threshold  lets say 1500 failsafe is activated.

          i am remapping because i am using a dx7s with a dragonlink system

          • Mauricio > Andrew John Britton September 28, 2014 at 5:13pm

            I'm still having the exact same problem. Anyone have clues? should we post somewhere else to get more replies? I'm pretty sure someone have found the trick, this should be a rather common setup. Help!

            • Dave Schmitt > Mauricio October 5, 2014 at 7:53pm
              Have you guys found a solution to this yet. The channel mapping makes sense but I need the failsafes to work. Have you guys tried what Bill Bonney said about disabling the ppm encoder? I've read it 10 times and still Have no idea how to disable it. I might just have to buy a 9xr as getting any descent direction here is almost impossible. Let me know if you guys have had any luck.
              • Mauricio > Dave Schmitt October 6, 2014 at 6:19am

                Haven't made more attempts recently. I'll try connecting the DL receiver with a PPM encoder just like other receivers and see if this helps. I haven't attempted Bill Bonney suggestion, seemed complex to me.

  • Luc Maximilien October 1, 2013 at 9:23am

    For the Graupner read this :

    http://diydrones.com/forum/topics/graupner-servo-channel-order?comm...

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