Unstable PWM signals to motors

If I plug a servo into any motor control port it buzzes at a constant frequency. The output arm will change position, however, if the throttle stick is moved. This means the PWM signal is rapidly changing pulse width even when it should be just one length. The “calibrate all” works well as does the throttle test at the end of the calibration. The motors behave as well calibrated motors should and a servo plugged intp a motor port is smooth and quiet. Put the Pix into flight mode, however, and the motor output is so inconsistent it confuses the ESC’s to the point where they beep and re-calibrate to a very short stick movement.

I attempted to fly like this and the motors were either on or off. Thankfully it could keep itself right side up but it was rockin’ and rollin’ like crazy with the motors firing off and on… “wham, wham, wham”. It would go where I pushed the sticks but was difficult to land without catching a prop. Cripes, what a challenge not to crash!

BTW, this is a newly built Turbo Ace Matrix.

So… what’s up? Is there a parameter or four I need to adjust? Should I try re-flashing 3.2.1? Should I return the Pix as defective?

Thank you!

PWM at the motor output is sent at 490Hz which is too fast for most servos. Additionally, the PWM is changing a lot in motor control.

Does the motor output change a lot even with the throttle full off and the controller disarmed? But the 490Hz thing makes sense, though the servo works great in the calibration test mode… that time right after the ESC’s chime to say they got the low point. Then when you use the throttle, the servo is very quiet and smooth.

In any case… after calibration the first “real” run up of the throttle results in no prop movement at all until the ESC’s do a “dot duh duh duhhh” (with the last “duhhh” a higher pitch) and then the motors will start. And each ESC will do this at a different time. And the calibration is all messed up again. It seems the ESC’s are not getting out of calibration mode? I can’t find any documentation on these Turbo Ace ESC’s.

During calibration test the motors will start at just 1 or 2 clicks of throttle and run nice and slow. After the first “real” run-up they don’t start until 1/4 throttle and turn pretty fast… almost flight speed.

This is not my first time at this. I had a really easy time with my last Pixhawk build. Frustrating…

Yeah, that sounds like an ESC issue to me… IIRC, in calibration mode, the Pixhawk is just passing the signal from the RX through 1:1, so the signal update rate is probably much lower.

Yes, that is true. That explains it. Thanks for helping me figure it out.