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Pixhawk causing motor sync issues.

Posted by xoltri on March 10, 2014 at 10:50pm

I believe I have a problem with my Pixhawk and was hoping for some help.  Also posted this on rcgroups.

The issue is that when my speed controllers are hooked up to the Pixhawk they exhibit a bad sync issue.  However when they are connected to my old APM (3.1) or just a receiver directly they do not exhibit these symptoms.  This has resulted in 4 crashes now until I just tonight narrowed down the issue to the Pixhawk.

Can anyone advise what is going on?  Here are the specs of my setup:

Afro 30A ESC's with SimonK firmware (have tried all versions, and made my own with various parameters)

Tiger MT2216-9 1100kv motors

4S 3700mah battery

https://www.youtube.com/watch?v=i7_gVoY8q8M

https://www.youtube.com/watch?v=VTK81IANyUE

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Replies

      • FlyHigh > xoltri December 7, 2014 at 5:01pm

        I also am a bit confused by the "dogs breakfast wiring". Having the ground for the ESC signal seems to be the only "error" in wiring I can think of. I have added a ground for the ESCs signal but still face the sync errors. I dont know how else you would wire my setup. The ESC power and ground is wired to the battery. The ESC signal and signal ground are connected to the pixhawk. The motor is connected to the other side of the ESC. How else could you wire it?

    • Artem > Rob_Lefebvre December 7, 2014 at 12:44pm

      That is why one needs to research both sides and use own experience + judgement. As stated multiple times in all my posts this is NOT pixhawk's fault but poor ESC quality. If it was pixhawks fault there would be signifucantly more people with this issue. 

      • FlyHigh > Artem December 7, 2014 at 3:13pm

        You have no proof of that. When 4 escs work perfectly on APM and the same 4 escs all experience extreme sync problems on pixhawk I would say pixhawk is the changing factor. Not the quality control of the escs. Something is off and no one seems to have it pinpointed yet. 

        • Moderator
          Nathaniel Caner > FlyHigh December 7, 2014 at 4:36pm

          I've been following this conversation with great interest and can't wait to hear the results of your trip to see Craig at 3DR with your quad. It will be nice to see what you find.

          I don't think you can make the assumption that because your ESCs worked fine with APM but not Pixhawk that something is wrong with Pixhawk.

          Hopefully you can find the smoking gun so to speak and find an answer to the question.

          Regards and good luck,

          Nathaniel ~KD2DEY

          • FlyHigh > Nathaniel Caner December 7, 2014 at 4:56pm

            Likewise I also don't think that because the ESCs worked fine with APM but not Pixhawk you can say its obviously the ESCs fault.

            • Moderator
              Nathaniel Caner > FlyHigh December 7, 2014 at 5:18pm

              Absolutely, I agree it goes both ways. Looking forward to some results.

              Regards,

              Nathaniel ~KD2DEY

  • DG December 6, 2014 at 8:52pm

    @ Artem

    How do the Spiders work? 6 just arrived and I'm debating whether to try them or not.

    I also have some XRotors coming.

    Thanks,

    DG

    • Artem > DG December 7, 2014 at 8:23am

      Spiders are awesome on the latest SK, but as with any SK 6s setup IMHO one needs at least double the amps of your motors. Otherwise they run hot. Xrotors are good, very good, not as good as spiders, but they run cool even between the frameplates. If you are lucky and get a new spider (there is no markings indicating new/old) they come with better fets and removed analog filtering caps. Old ones are great too but at 6s get toasty hot inside the frame and even too hot for my liking under the prop. I have a set from April/May wich I now use only on 4s setup, they never skipped a beat though.

      • DG > Artem December 7, 2014 at 2:45pm

        I have the latest ZTW Spider version according to Altitude Hobbies, who graciously took back the Maytechs that would not spin up (out of 8 could not get 6 to sync). In their view the Maytechs should have worked fine. Whatever. The 3DR ones are working with only the signal and ground wire attached, but are not very responsive compared to in the Y6B. 

        The ESC's are currently in the tubes, but I think that's going to change and reside in the frame where there is good airflow. It's only 30-35F here so heat is not a problem, in summer that may not be the case, although many do without issue.

        @Rob,

          I appreciate your input on all issues related to MR, and I'd like to think I did something wrong regarding the wiring, but I read every thread I could find on the subject and cannot find anything that would indicate incorrect wiring. I don't use O'Scopes and wouldn't know how to test an ESC anyway.

        All I know is out of 8 brand new Maytech OPTO ST ESC's, independently using the rx they calibrated fine, no sync problems, throttled up nice. Once all six were connected to Pixhawk, there was horrible sync issues. I have no idea why, it doesn't make sense. Maybe there was one or more bad ESC's; seems unlikely more than 2 out of 8, but possible I guess. Throw in the 3DR ESC's, the copter flies.

        Hopefully the ZTW Spiders will play nice with these KDE motors, and then the XRotors with adjustable timing will be interesting to try.

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