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DRV8825: Motor is stalling at certain speeds. How to resolve?

Stephen Karlsgodt
Prodigy 200 points
Part Number: DRV8825

I'm using the DRV8825 driver and having trouble with (unloaded) stepper motors 'stalling' at some speeds.

In this application I need the motor to spin at at max of 1000 RPM. I'm using a quadrature encoder knob and small MCU to generate the step signal into the driver.

Things seem to be going well, but at some speeds the motor just stops rotating (i can also hear audible noise from the motor). 

I've read that this has to do with a natural resonance in the motors., and have tried different micro stepping settings, and different decay settings, but nothing seems to resolve the issue. I've tried two different steppers models and they both do the same thing.

What can I do to resolve this?

Thanks

  • 0
    TI__Intellectual 2550 points

    Hi Stephen, 

    You are correct. Resonance in steppers leads to audible noise. This can happen at specific speeds. Two possible solutions could be:
    1. Try changing the speed by a small value if some amount of variation is admissible in your system. 
    2. Try changing the value of full-scale current by changing xVREF (refer to 8825 datasheet here). 

    Let me know if this helps.

    Regards, 

    Karan

  • 0 in reply to Karan Doshi
    Prodigy 200 points

    Thank you Karan,

    I have found that when driving the step pin from a signal generator the motor performs much better.

    The MCU dev board I have been is using the default RC oscillator. Is it possible that the low-precision time base is the cause of the issues?

  • 0 in reply to Stephen Karlsgodt
    TI__Intellectual 2550 points

    Hi Stephen, 

    It could be the case. If the step input from the signal generator solves your concern, we can conclude that the DRV8825 is working expectedly. You might want to inspect the MCU. 

    Please let me know if you have any other questions. 

    Regards, 
    Karan