More problems.

Grasping at straws at this point.  Had an actually good flight, did my first loiter and RTL failsafe that went well.  Was getting more confident and decided to try out the vertical performance of my quad, and then this happened (0:46 and 1:00 in the video):

Any help is appreciated.


You need to be a member of diydrones to add comments!

Join diydrones

Email me when people reply –


  • Looks like you had one of those puckering up moments. Good recovery. I looked at your RCIN and I think your receiver went into failsafe as all the signals went to 0. The three common receiver failsafes are hold last position, go to a preset position or no signal. I believe your receiver lost the rf signal and went into a failsafe that sent out no signal. You can set up your Pixhawk if no signal is received go into failsafe.

    The other possibility is your radio had a brown out but your VCC voltage was good. Another thought is you could have a loose connection somewhere between your receiver and the pixhawk. Either in the cable or maybe a bad solder joint in the receiver or pixhawk.

    I would bench test the radio and the pixhawk. Take the radio and walk far away and look at the log when you loose signal. You can also just turn off the radio to see what the transmitter does. You can use mission planner to give you live reports of the signals while testing. 

    I would set up your pixhawk and receiver to do no signal failsafe. Other than that great flight and video

    Hope this helps


    • Thanks for the reply.  The receiver is set to go to the values it has when it first boots, so neutral sticks and throttle at 989.  I guess it is possible the receiver glitched for some reason and sent the 0 values, but shouldn't it have then triggered a throttle failsafe?


      I have my transmitter set up that min stick throttle is 1100, and when I flick my throttle hold switch it goes down to 989.  Throttle failsafe in the Pixhawk is set to 1010.  I always boot the quad with my throttle hold on because the receiver resets failsafe positions on boot.  This way RTL will be triggered when either the receiver loses signal or if I flick the throttle hold switch (ie if I loose video or something).  So why wouldn't the Pixhawk, when seeing a 0 value for throttle, have triggered a RTL failsafe?  It did it fine in my test when it received a 989 value for throttle.


      I can accept that maybe there is something wrong with my Assan receiver and it was actually sending 0 values to the Pixhawk.  I was looking for an excuse to upgrade anyway and I've already purchased FrSky replacements, but the failure of the Pixhawk to trigger RTL is what has me most concerned.  It was only luck that I got the quad back, if the glitch would have continued it would've crashed.



  • I'm bumping this because I've yet to receive a response.  I've already purchased a new transmitter and FrSky receivers in the off chance it was my Assan hardware that was causing this.  I have done some bench testing but have not been able to recreate this issue.  My receiver is connected via PPM Sum with one cable to the Pixhawk.


    My biggest and most concerning question though is why the Pixhawk took the 0's as valid input.  I have a throttle failsafe set up so any throttle input below 1010 should've triggered it, but it didn't in this case.  The entire reason I went with Pixhawk instead of something cheaper like a KK was for the failsafe and autopilot, so the fact that it didn't work in this situation is very concerning.

  • Ok I did some more digging and can ask a more specific question.  The two glitches appear at just before 21,000 and just after 23,000 in the logs.  It looks like it received a roll and pitch (and possibly yaw) command, which is really odd, because I can guarantee I did not move the stick.  Can anyone confirm for me that is what happened?

    If this is the case, the only theory I can come up with is that there is something wrong with my transmitter.  It is a Turnigy 9x that I've had for several years.  I don't think it would be a signal issue, as my receiver sets failsafe on boot which means that on failsafe it would've went to 0 throttle and all sticks at neutral, and it also would've initiated an RTL.



    • Yeah you can definitely see the same issue on yaw vs desyaw.  So why does it appear it received simultaneous drastic yaw, pitch and roll commands?


      • More digging, zeroed in on the problem (literally) in the logs but I still can't explain why this would happen.  Any advice is appreciated.  Also confused why it didn't trigger a throttle failsafe and RTL.  I have the two examples of this on this flight and one more from the previous flight where this happens, so I am not safe to fly until I find the problem.

        I'm using an Assan TX/RX in a Turnigy 9X transmitter.  Maybe it's time to upgrade?


This reply was deleted.