Pixhawk apparently losing ESC calibration data

Hi All,

I have a situation where after upgrading to some high-end ESCs, I have one at random go into calibration mode. This happens on about 1 in 4 flight attempts. The only way to restore proper operation is to repeat ESC calibration with Mission Planner.

I have had a dialog with the manufacturer about the issue. His position is that the problem is cause by the Pixhawk EEPROM not retaining calibration data, and that it is a known issue. He has seen it with a number of customers over the years. The solution was apparently replacement of the FC.

I'm not so sure. I've only had problems with the new ESCs. The Pixhawk worked fine for a couple of years with my previous ESCs. 

On the other side, my Pixhawks are out of warranty and 3DR isn't supporting them anyway.

Has anyone else seen this kind of issue?

Thanks in advance for any info.

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  • To close the loop on this issue...

    After programming fixed throttle endpoints in the ESCs, my problem seems to be resolved. The is not the preferred solution, but it is an acceptable work-around.

    Thanks to all for the help and suggestions.

  • Thanks Emin. I appreciate the info!

  • I hesitate to give a name, only because the supplier has been very helpful in every other way. For the most part, they seem to provide a very good product. For example, the motors and ESCs that I bought from them take my TBS Disco from 10-12 minute flights to 14-17 minute flights, without any other changes or reduction in performance.

    I can tell you that it is not ReadyToFlyQuads. They are also not SimonK ESCs. The firmware is proprietary. I realize that not giving a name ties everyone's hands in helping, but I think it is the best course.

    The supplier's reasoning is that when other customers have had the same problem, replacing the Pixhawk has cured it. I suspect that the situation is not so simple as that, and that it is more likely that there are configuration differences. I haven't had a chance to get a scope on the PWM signals yet, to see what is actually coming from the Pixhawk when I press the Safety Switch, so I don't really know. If the fixed endpoints work, I may not worry about it.

    So far the fixed throttle endpoints are working. Not very many flights yet, maybe 4. 



  • First,ask the seller is programing with TX enabled...if not,ask him how to do it

    <You can also send him my advice..advice is for BLHeli..Problem is i do not know SimonK so well as BLHeli firmware,but as i know they work on same principle...

    Second,ask him is OneShot or OneShot125 is enabled bcs. only the latest software of Pixhawk might work with that..latest is 3.4 rc4 (you can download that if u go Instal firmware,beta uploads...don't be afraid bcs it is rc4(release candidate) everything is fine... 


    Third,if you have any more question you should better post that in ARDUCOPTER.ORG where most of developers answering questions(Randy included)...most of them do not go here...

    here is link:


  • thank you for you advice Emin. We get this one : http://www.readytoflyquads.com/rtf-escez-30amp 

    Cheap but hours of flight without any problem. Except when we used it with pixhawk....

  • So...if it is this one 

    ReadytoFly ESC 30A 


    you have SimonK on it and you need adapter to program them....u can do that only if servo connector is available(be aware it is not servo conectors wich go to RX,but separate one for programing Eprom).. 

    When u calibrate them,box with "program with TX" must be on(if its not,they wont calibrate)....and than u do normal all at once calibration...after u finish calibration,this box must be of or otherwise every time u have you throttle high they will enter calibration mode...

    In Mission Planer be sure its not 1-"one shot" or 2-"oneshot 125" but 0-"normal"

    Also in mission planer set throtlle range from 1000 to 2000........

  • What esc is this,give us name and link?BLHeli(or SimonK) software on them or not?

  • we have the same behavior : with APM series, ReadytoFly ESC 30A work very well. With Pixhawk, it is a nightmare. Some time working, some time not. We change them for Afro series : no more problem. We spend almost 1 week to understand  - no way to resolve it.

  • Thanks for the additional replies.

    My experiment failed and I've started another. These ESCs can store a fixed PWM range, so I set that to match my RC calibration values, with a little margin.The aircraft flies OK this way, though take-off isn't quite as smooth. I'll update with results when this fails or I have some confidence in it.

  • Thanks for the ESC info.  Still looking for some help vis-a-vis the motor-not-starting problems.  I've had only one other 'copter prior to this 550 hex and I don't recall having that same problem with it.  But then that 'copter had a completely different type of built-in F.C. with on-board FPV and no GPS, so I think I would be comparing apples to oranges if I compared the wo 'copters. 

    Andre K. said:

    No, ESC throttle range calibration is something an ESC is supposed to remember. Arducopter stores RC calibration to know the range.
    Some ESC s, (usually beforenentioned open source) *can* also be programmed with preset pwm range, not needing, nor being able to be calibrated.
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