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



Views: 47140

Reply to This

Replies to This Discussion

I like how people say "its not a pixhawk problem" even though it was never a problem with APM or multiwii. Its like saying "we built a car with square wheels and its the tire manufactures problem for not making square tires..."

Sorry, I've been through all of this and still I have to back up FlyHigh, there is something odd with the Pixhawk (even despite what 3DR is saying).  

If you watch this video, you can see that even with the ground wire connected it still has the problem.  The biggest point though is that if you remove the power module (at least in my situation) it seemed to resolve the issue entirely.


Furthermore, this other video shows that my motor and speed controller itself passes bench test, unless connected to the Pixhawk.


And another video that shows the same situation, where a speed controller works fine when not connected to the Pixhawk, then exhibits the problem when connected to the Pixhawk.  This is a non-simonk speed controller.


Even though my quad is working properly now with 3DR branded speed controllers, this issue still frustrates me when someone waives their hands and pretends the problem doesn't exist.

Been using pixhawk/clones since August on various setups ranging from 3s to 6s, 8"props to 17" props, 340kv, 380kv,  400kv, 700kv, 750kv, 980kv without problems. ESCs afro 30a, afro 20a slim, ZTW spiders 20A, 40A, HW xRotor 40a.  Always bench tested my ESCs with your method before putting them on a model with GND connected to pixhawk. as far as I was able to research the problem is with certain ESCs not handling 3.3v PWM correctly. I've seen cases where two 30a afros with the same SK one was causing issue the other was not. On opening them up I could clearly see differences in PCB quality, soldering and even one had afro mark on silkscreen the other one didn't. both ESCs were purchased from HK within one month of each other in April, never had issues with 20a slims though. 

p.s. in my opinion it is more like some motors are designed to run on 91 grade gas, others on 87 grade. same with pixhawk, it is designed to run well with quality ESCs. most of the high grade MCUs these days run on 3.3v, days of arduino are almost gone, unfortunately some ESCs cannot handle 3.3v PWM correctly due to design others due to QC issues. guess what happens if you put 87 grade gas into Audi Q7 repeatedly?  

But when you open the gas door on that Audi it says "high octane gas only"

What pisses me off is the extremely dismissive attitude of "this is an esc problem not a pixhawk problem." When someone says that it does nothing to help the situation. That is not a helpful solution. I understand 3dr cannot test every esc out there, nor would I expect them to. But when they only make one single 20a esc and refuse to back any other manufacturer that makes it extremely difficult to use their product. I want to use pixhawk. I paid for a genuine 3dr  board because I did not want to deal with issues like this and expected some customer service. If they said "ya those escs can be problematic but we have had good results with XXX brand of 30a escs." that would be tremendously helpful. Instead I am blindly wading through forums trying to figure out what ESCs to use with their product. Other flight controllers don't have this problem with picky escs, so I would not say that its not a pixhawk problem. If you want to compare it to cars, apm and other flight controllers were like a car that can run on any grade fuel plus bio diesel. Where pixhawk is the very pick sports car that requires something very specific, but what that is exactly is a mystery since 3DR won't tell us.

admit, 3dr is not the best cs company. an they should definitely address this incompatibility at least as a good will measure. 

We have yet to see a single ESC that does not work with the Pixhawk when it is properly wired.

If you have an ESC that does not work, please send it to me.  I would love to review it and determine what the issue is.

>>>as far as I was able to research the problem is with certain ESCs not handling 3.3v PWM correctly

Please show us your research.  I would love to get to the bottom of this once and for all.

but again, it is very sporadic, as I mentioned I had 2 30a afros both from HK on the same SK version, one would loose sync one would not. in this case it is more of the QC problem with afros than a 3rd issue. I personally torture test each and every ESC before I put it on a rig. it is so much easier than to rebuild a copter or someone's roof or car..... or skull..(if repairable at all) 

Craig I am in Los Angeles. Are you in San Diego? I'd rather bring my whole setup down to you than ship anything. I know xoltri shipped you a motor and esc and you guys said you were unable to reproduce the issue. If I bring my setup down well have no issue reproducing the problem.

lol, under research I mean "forum research". 

ok so you mean you read it on the internet so it must be true.

Yes, I am in San Diego.  It would be great to have you come down. Thank you.  I will PM you to arrange a day and time.

Reply to Discussion


Season Two of the Trust Time Trial (T3) Contest 
A list of all T3 contests is here. The current round, the Vertical Horizontal one, is here

© 2020   Created by Chris Anderson.   Powered by

Badges  |  Report an Issue  |  Terms of Service