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DRV8825: DRV8825 drives motors between 999Hz to 2KHz

Male Hakim
Prodigy 10 points
Part Number: DRV8825

I'm using the driver to drive a Nema 17, 400 steps/rev motor using STM32F303. The problem is that when i go to frequencies of the PWM signal below 1KHz and above 2KHz, the motors stall with a high pitch sound. When i drive the Step pin from a square wave signal generator, i go maximumly to 10KHz. I thought my PWM signal from the STM32 should be at least 4v in amplitude as compared that of the signal generator but still i cant get passed the 2KHz limit. Anyone who has any idea what the cause could be?

  • 0
    TI__Guru 56650 points

    Male,

    First, the step pulse frequency is not the PWM frequency. The PWM frequency is the FET switching frequency for the winding current regulation. 

    DRV8825 PWM frequency is about 30kHz which is higher than the audible range of human ear.

    According to your description, the motor doesn't have the audible noise with the square wave signal generator up to 10kHz. But, the motor has the audible noise with  STM32F303 when the step pulse below 1kHz or above 2kHz.

    If we assume the square wave signal generator frequency is accurate without any jittering on the rising edge of the step input. At each rising edge of the DRV8825 STEP input, the indexer travels to the next state in the table. If there is a jittering on step pin rising edge with STM32F303, a low frequency noise could be generated and cause the audible noise.

    Please check the step pin input first to check if there is jittering on the rising edge of the step input. I would think the STM32F303 clock is also accurate, please synchronize the rising edge of the step input with the STM32F303 clock.