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



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                • Thanks artem, quite stupid indeed! But I'm freaked out now with this quad, nothing goes to plan! Thanks again.... I tested the motors with the stock firmware, and on servo tester, it is pretty good with high impulsion, let's see now how will they perform once reconnected to the PIxhawk.... Tks again much appreciated for your great simple basic comments, I am implementing them to the letter, and minimize forthcoming problems.... Take care. Cheers and Safe Flying Lads!

                  • Don't worry and do not panic, out of my experience most of the sync losses are actually due to the poor electrical connection of ESC to the motor or motor quality itself and only once it was a bad ESC (multistar v2 slim). Take care to salder your motor leads to the ESC than check each ESC/motor/prop with your fligh pack for sync loss on the ground with a simple servo tester.  

            • Thanks ever so much,, I will rebuild it from scratch I think, it'll be

        • Are you twisting both the power cables and the signal wires? 

          My particular build is a Tarot FY680. This build will require about 35mm extensions on the signal wires, and both the power wires and signal wires run inside the carbon tube arms together. Lots of length for them to couple, unfortunately.

          It was mentioned in a prior post using cat5 cable for the signal wires but I couldn't figure out if they meant to strip a single twisted pair out of the cable or if they used the entire intact cable. 

          Someone should make opto isolated ESCs with fiber optic signal wires so the LED plugs into the flight controller and the photo transistor is on the esc board. 

          Is there a simple, external way to boost the signal from the pixhawk to 5V before sending it to the ESC?

          • I'm running afro 20a slims from a pixhawk on tarot 650sport.  I've recently extended it with the older 650 arms (which are quite a bit longer) so it's now an 800, with 15" props on 3508 motors.  The ESCs are flashed with blheli, and I extended the motor->esc wires instead of the esc->pixhawk wires, but signal and power lines are run together in the arms with no twisting.  I've done hundreds of flights with zero issues, except for a single flight that I changed the blheli settings to damped light/braking mode and I had a desync.  Changed it back to High frequency and not had a problem since.

            My sunnysky v3508 580kv motors do screech a lot though - I read somewhere this is possibly something to do with the waveform that comes out of the afros.  Elsewhere I read this is a potential sign of a motor about to desync, but I've never had a problem with many flights except the one which is understood.

          • Wiki Ninja

            Opto-isolated escs? Anything useful in http://copter.ardupilot.com/wiki/connect-escs-and-motors-pixhawk/#k...

          • II am using Afro slims which have the same hardware as afro 30a and the same f/w but do not have BEC so no wires and my installation is inside the 16mm tubes.  So no extensions at all just twisted signal and gnd. 

  • My first post in this forum, as I am now just about to give up on my Pixhawk project...

    I have the exact same problem as Xoltri.

    I had my Pixhawk for about 7 months now, and still not beeing able to get it off the ground. 

    This guy on Reddit describes the problem I also have, and it sound very much like the one Xoltri have (has?)


    Quote: "...SUDDENLY all the motors went to full power. No grinding noise anymore. I closed the throttle but nothing happened it was stuck wide open. I tried to disarm but it wasn't responding,"

    Specs on my setup:

    Pixhawk from Hobbyking, with the newest 3.2.1 firmware from MP.

    Sunnysky X4108S-14 KV 480

    KISS ESC 18A 

    4S 5000 mha

    It feels like it will not take the throttle, and the suddenly above 50% it goes crazy... I have managed to get it in the air 1 time, this is after I set RC_SPEED to 100, but it is no where easy to get up, and I must admit, I am a bit afraid of those 15" carbon props on a machine I cannot controle.

    I have followed all the official guides out that, calibratet motors, ESC's compass etc. 7 or 8 times now and still no luck.

    Can anyone help me on this problem?

  • Craig and OG, thanks for quick reply.

    Actually what I though was a problem was not really a problem with Sync or rather no problem at all. What happened was the following: when I draw up the throttle stick not all the motors started to spin at the same time, some sort of delayed on 1-2 motors till I draw throttle bit more. Then everything works perfectly fine. I had a 15 minutes nice flight, no issues at all!

    Therefore I confirm that the latest Afro 30A ESC with SimonK bought one month ago from HK are compatible with Pixhawk on Arducopter 3.2.1.

  • I am sitting with the Hexa and Afro 20A ESC and expiriencing this same issue.

    Is there any "consensus" about the problem and a common solution? 

    Is latest SimonK firmware working with Afro ESC with Pixhawk?

    Will reflashing ESC with BLHeli fix the problem ?


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