QT PY PWM issue

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NuTrix
 
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Joined: Sat Nov 14, 2020 12:26 pm

QT PY PWM issue

Post by NuTrix »

Hi,

I'm using the Adafruit_Motor library to control (PWM) a brushless speed controller.

Here's the WEIRD part..

When the QT PY is powered via USB, the motor is stopped (neutral) with this command:
my_servo.throttle = 0.0

As it should be, but..

When the QT PY is powered via a battery, the motor does not stop, I need to offset the value like this:
my_servo.throttle = -0.095

Why is that?

Thanks

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adafruit_support_mike
 
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Joined: Thu Feb 11, 2010 2:51 pm

Re: QT PY PWM issue

Post by adafruit_support_mike »

Offhand I have no idea.

At a guess, it may have something to do with the rising and falling edges of the PWM pulses, and the motor controller’s voltage thresholds. To get a better idea, you’d probably have to look at the signals on an oscilloscope.

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