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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Im not as "technical" as everyone on here. Im a merely an end user. I am the target market. I am a simple RC enthusiast.

As a "user", Im very keen that people stop pointing fingers and start working on a solution, so my question is:

1) Is this recognised as a problem

2) Is someone owning a solution

3) When will the solution be ready

The answers to above will help me, and the rest of the market decide where we take our "investment" in the future.


I had a similar problem with my afro esc and some Sunny Sky 2300(ish) motors for my mini quad. Predictably for a while i could always be sure that within 2-3 minutes one motor would cut out. Since it would randomly pick different motors each time, i was pretty sure it wasnt the motors that were bad or the escs. In the end the solution to the problem was flashing the esc with the latest SimonK firmware and the motor stops are gone.

When i was testing, i would simply hover and move about slowly about 50cm above the ground in manual mode and sure enuff it would cut out. Even when i crashed it wasnt from very high, and nothing ever broke. I guess iwas trying to demonstrate to myself the problem was reproducable. Everything else was fine, batteries full etc. 

I ve got quite a few simonK afros on regular sized multirotors and have never had an issue, but it cant hurt to flash them, things can only get better :)

Not admitted as an issue. Do not care about end users who have it. 

No response then....

Seriously, people are looking at it. When there is useful info, it will be posted. I have not yet been sent a single motor ESC combo that behaves like this when wired correctly, so, if you have one, and it's behaving badly, and you have it wired correctly, ie signal and ground connected. Feel free to send it into 3DR, and mark it att Philip
I would be more than happy to look into it further.

I sent in the combo to Craig @3DR from this video: https://www.youtube.com/watch?v=u_KZ5K0R7eY&list=UUYZ_ZGYHxt_CX....  He still has it.


He was not able to replicate my issue though, which was odd since I think the issue was pretty clear in the video.  In any case, my issue was resolved when I bought 3DR speed controllers so I did not pursue it further, aside from following the thread occasionally.

I still have your motor sitting here on my desk.   I was going to send it back to you but that was right in the middle of the "No exports" mess.  If you want it back let me know and I can ship it now.

In the meantime we have tested it with a bunch of ESCs and it works perfectly when wired correctly with the signal and return connected. 

Afro esc working ok with your bec power, if use external ubec, lost sync and not good workin. Cable length is also an issue. 

Dan thanks for your reply.  Sorry that it has taken more than a month to put this into use but parts and life sometime get in the way of a ground-up rebuild.  

I flashed all of the ESCs and took the prop down to a 10x4.5.  Test flights went very well and I was seeing no signs of sync issues on the ground or in the air through the first couple of packs.  Loiter and AltHold tested fine without issue (in the past AltHold has caused a sync issue) so I thought we might actually be good to go.  

Now, I had used autotune with the 10x4.5s several times without issue.  I suspected that I was pushing my luck with the 11's so with that delusion I put the tricopter in AltHold and hit the channel 7 switch.  This time I didn't even get a twitch, it just rolled over and into the ground.  Fortunately, I only popped some zip ties for once instead of shattering carbon fiber booms and breaking frame plates.   

Honestly, at this point I am going to trash out the Afro escs and go with something else, probably the Hobbywing xrotors for now.

I just moved from APM to Pixhawk and having massive sync issues. I'm using Afro 30a escs with SS v3508 700kv motors. They flew perfect on APM but as soon as I wired up the pixhawk I was having tons of sync problems, I can't even power it up fully. Below is a video of my issues. I've read through this thread and seen people post about having a ground wire for the signal connected (right now I only have signal) i've also seen mention of flashing new firmware on the escs. Can anyone confirm that either or both of these solutions will solve my problems? If not I'd much rather just purchase new escs that work well with pixhawk. I need 30a though and the only escs i've seen posted that work without issue are the 20a 3dr. If the two solutions above won't work with 100% reliability (as far as 100% is achievable) then can someone recommend a different brand 30a esc that will work perfectly with pixhawk?


Yes connecting each ground of each ESC to Pixhawk will solve your problems !

Rewired my quad with grounds for all the ESCs. It might have helped the problem but it is still completely unflyable. It just takes a little more power than before to bring up the sync issue now. I have a usb linker on the way and will try flashing the latest simonk firmware. Hopefully that will cure this problem. 

Sync loss is not pixhawk problem, but esc/motor issue. out of my experienceif an ESC / motor combo passes at bench test  for sync loss pixhaw will never be an issue as long as all grounds are connected. Update your ESCs f/w this should solve the problem.

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