Pixhawk causing motor sync issues.

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



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

Join diydrones

Email me when people reply –


    • If your motors draw 20A @6s and you want SK ESCs, go with at least double the amps. With simonk f/w 20A ESCs tend to run really hot even with max 17-18amp per motor current draw -tried 20a spiders, 20a multistars, Sunrise 20a all good ESCs which happily run on 4s setups. I think this is because sk firmware makes very fast and frequent throttle changes.  40-45 amps ESCs are just warm after the flight. Considering that difference is about 10g per ESC between 20A and 45A go for 45amp ESC. Very good SimonK ESCs I have found are ZTW Spiders. Hobby Wing xRotor40A are also  a good choice, not as responsive as SK but much faster than platinum pro and run just barely warm to touch . If you are into flashing your own f/w and price is not an issue I have found Turnigy Kforce 40A flashed with blheli as responsive as spiders, but they run at ambient temperature so for extra piece of mind and if the budget allows definitely go for them. spiders work with pixhawk and 22pole 380kv motors at 6s, but need airflow to remain warm, get somewhat hot in between the plates. Currently using HW xRotor 40A, those are solid, run barely warm even with 0 air flow, not as responsive as spiders, but I am using them on my AP rig and I like it being smooth anyways, autotune yields similar PIDs.

      • Artem,

        At hover my copter draws < 4A apiece on 4s. It is 3.1kg and using 14" props. I have a set of ZTW Spider 30A Opto (small version) and am contemplating trying them. I had Maytechs but could not get them to sync.

        The motors are KDE 2814XF-515.

        What do you think?

      • Artem - thanks very much for the suggestions.  From this thread, it sounds like the most likely to be problematic combination is Afro (SimonK-based) + Pixhawk.  The max. I can get eCalc to generate (with different prop options) is about 15A, so using 30A+ rated ESCs makes sense.  The ZTW Spider is currently looking like the best option.  It's widely available, not a lot of reports of problems (with Pixhawk or otherwise) and fairly light at 25g for the 30a model.  Having the option to re-flash to BLHeli in case of problems is also appealing.

        • I have 6 ZTW OPTO 30A Small Spiders ready to install, but also have a set of HW XRotors coming. 

          I'm hoping to try out the Spiders this weekend and will post if there are issues. 

  • Hi all. Has anyone tried to reduce the RCSPEED parameter in MP to 400Mhz or less? I had a few issues with escs some time ago and now I change that param on every fresh install. I don´t have enough knowledge to ilustrate why it could work but I guess it´s a simple test

    • A long time ago, it doesn't fix the problem.
  • Update: RTF Y6B running 3.2 vs 3.1.5 Pixhawk

    3.2 motor6 always spins up but at some random point drops sync before regaining sync.  Frame drops left arm.  From Zero throttle 1st time is smooth.  Subsequent throttle ramps from zero all motors jump up to about 30% throttle, above 30% all good.

    3.1.5 No sync issues.

    Tried: Replaced ESC-6 No change

    Replaced Motor-6 No Change

    Reflashed Board No Change

    Swapped ESC-6 and Motor-5 for ESC-6 motor-6 Not change Motor-6 still dropping sync.

    Checked all connections, tried moving power/ground from 3DR power module to Motor-7 port, no change

    Checked logs for power issues, no faults.

    Reverted to 3.1.5, All good, no sync issues.  Motors spin up smoothly as expected every time.

    I will try another 3DR Pixhawk board.

    Any ideas?  I tried the support forum but go no response I also raised this issue way back on 3.2rc-2 but though it would be sorted with the release version or that I would have located the problem. It feels like an ESC/motor or wiring problem but I have replaced and swapped all of the possibly faulty components and the problem never moves and it always works fine with 3.1.5.

    • That's interesting because this new Y6 was started out of the gate with 3.2; never thought about reverting back to 3.1.5, may do that with these ZTW Spiders if I have the same problems as with the Maytechs.

  • An update to my story. I have received my usb flasher and flashed all my Afro 30a escs to the latest simonk firmware. This has reduced my problem but not cured it. So to recap. Initially I was using only a signal wire. Motors sounded like they were grinding at anything above idle and would miss at idle and click. I connected ground wires for all escs. Motors would idle ok but at higher throttles they would still grind and lose since. Now with updated firmware and grounds still connected I do not get the intense grinding sound. I get a high pitched whine and under quick accelerations get a bit of a grinding sync sound. I have no confidence to fly the quad. Below is a video from the latest test. I test all motors individually at 30% power, then again at 20% power then arm and do some throttle ramps. The sync issue is most noticeable towards the end of the video when I am giving quick jabs to 50/100% power from zero. Reminder none of these issues were present with I had the quad configured with APM.  I will be either taking a trip down to Craig at 3dr with this issue or at the least sending my escs in for them to test. 


  • Hi All, I have been watching this thread and am amazed by the venom from some.  Aren't we all trying to find a solution.

    before I get into a rant:

    I have a sync issue with my 3DR BUILT,  RTF, STOCK, Y6B running anything higher than 3.1.5 firmware.  It seems to be fine running 3.1 but on 3.2 rc2 thru 14 it keeps losing sync on motor 6.  I have change the ESC and mar and all associated cabling to this motor with no change.

    Original wiring was done by 3DR wit all GND/Power/Signal wires connected to the 3DR power distro board and then all signal wires connected to Pixhawk and one set of power/grown connected to Motor6 Port.  I have checked continuity and resistance on all connections and they are good.

    COme to think of it I will try moving the power/Ground connection to another free port like Motor7 as it occurs to me that this is the only difference between the intermittently faulty motor position and the others.

    Another symptom I have observed is that idle speed seems to turn motors fine on first arming.  Once I throttle down motors do not spin (Not disarming) but when I ramp up throttle motors jump to about 30% speed.  Once I raise throttle to above 30% they track fine but Motor6 will lose sync.

    This is all original 3DR parts and wiring so hopefully that should avoid any comments about spaghetti wiring, mixing grounds etc.

    I have been flying a small250 size quad with 3.2 for a while testing before I tried it on the Y6B and it has been fine with all types of ESC's. If I go back to 3.1 then I have no problems.

    HELP!!!  I have already pulled my machine apart several times and changed/replaced and swapped ESC's and Motors.

This reply was deleted.