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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Not really, it means that I read both for and con arguments and made an informed decision based on the info I was able find about this issue. After all there is plenty of info suggesting that 3.3v pwm can be the issue and I still could not find an ironclad reasoning proving otherwise. As I mentioned in all of my precious posts it is more of the ESCs quality and design with pixhawks 3.3v pwm.


It is simple to check if 3v3 pwm causes the issue, just use any spektrum receiver, they are all 3.3v pwm output!  As proven here


Again, as mentioned, i think it is both 3.3v pwm and QC of some of ESCs! Reading back few posts I mentioned that I had 2 afro 30a on the same SK verison one would loose sync one would work fine. And as seen in the xoltry's video he doesn't use a 3.3v RX, I want to see another video of those ESCs/motors with a 3.3v RX I think it could be even possible to supply only 3.3v to a frsky RX and perform the test again. 

>>>After all there is plenty of info suggesting that 3.3v pwm can be the issue and I still could not find an ironclad reasoning proving otherwise

Look at the 3.3 V signals coming out of these receivers and compare them to Pixhawk.


I recently built a Sky Hero Spy 750 w/KDE 2814XF-515 motors and Maytech OPTO ST ESC's.

It has Pixhawk (genuine) FC.

rx: Frsky x6r using Sbus

I could not get 6 motors to spin with those Maytechs; a total of 8 ESC's. I thought it must be the ESC's, so returned them in exchange for ZTW Spiders which haven't arrived yet.  Independently using the receiver to calibrate ESC's, the motors sounded great, until everything was hooked up to Pixhawk. It did just what was in the video above. I spent hours reading, trying different things, thought for sure I must be overlooking something.

So just for fun I took one ESC off my Y6B to replace one Maytech and all six motors worked! I then replaced all the Maytechs with the 3DR ESC's and I was able to fly. A bit sluggish, with a some sync problems at lower throttle, but the copter flies. The ESC positive wires are not connected to Pixhawk. 

On the wiring side, I use a HobbyWing UBEC for the rail, and 3DR PM going to the power connecter on PIxhawk.

I also ordered some HobbyWing XRotor (non SimonK) to see what they do.

After reading this thread I'm not having warm fuzzy feelings that putting on different ESC's is going to fix the problem, although Kloner said the Maytech worked for him and the ZTW Spiders did not:


I certainly hope there is a solution and it is something I'm doing wrong, but I'm not seeing anything could be incorrectly wired.

There is also this thread that discusses issues with Pixhawk and power connections:


I'll be watching this thread closely as although the 3DR ESC's are "working", there still are sync problems particularly at low throttle and I suspect the timing is too low for these lower KV motors. So KDE has their own at $58.95 apiece; something I wanted to avoid, but at this point if they make the motors perform, I'm nearing the point of desperation.

See my post about Maytechs not working on my KDE motors.

I should note Kloner referenced in the above post was using Naza, not Pixhawk.

Craig, this is exactly what I saw when I was "researching" this issue, but showing that pixhawks pwm is almost identical to other RXes pwm doesn't prove much except implies that those ESCs which have issue with pixhawks should have issues with these RXes IF the 3.3v at fault. This should be easy to check, lets ask xoltri to make a video of him doing exactly the same test with the ESC/motor which proved having issues with pixhawk but with an RX supplied with only 3.3v I cannot do it myself as I threw out that afro 30a ESC long time ago and currently use spyders and xrotors. 

@ 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.



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.

FWIW, I've got several Hobbywing Quattros in use with Pixhawk, never a problem with those.  I also have some of the new Hobbywing Xrotors coming so I'll give those a test.  

The problem with this issue is that a lot of the people claiming to be "experts" on the forums, and talking about what works, what doesn't work, really have no idea what they are doing.  Monkeying around with test setups, flashing different ESC firmwares, etc, without understanding what is actually different in the firmwares, nor hooking up an Oscope, etc.  They're really just playing the lottery. It's not science.

Craig has been asking people to send him a "defective" system for a year, and nobody does.  Actually, I think one person did a while ago, and the wiring was a dog's breakfast.  It worked fine after some tinkering, IIRC.

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. 

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