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DRV8824: When DRV8824 is used to drive the stepper motor, the rotation direction of the motor is occasionally inconsistent with the direction set by DIR

user4637774
Intellectual 550 points
Part Number: DRV8824

We are using DRV8824 to drive the stepper motor, and the rotation direction of the motor is not consistent with the direction set by DIR. Have you encountered similar cases of this problem?

Please refer to the measured waveforms below：

Two waveform comparison:

Normal forward waveform：

Abnormal forward  waveform（Actual motor reversal）：

  • 0
    TI__Mastermind 23421 points

    Hello,

    Are you allowing the motor time to come to a complete stop before changing the direction?  And have you tried with an acceleration ramp up/down?

    Can you measure the voltage directly on the direction pin to make sure the voltage is complying with the high/low voltage spec?  Looks like your logic analyzer was on digital mode not analog. 

    Try lowering your VREF voltage - driving a motor with too much current can cause abnormal behavior.  

    Lastly, do you have a current probe or a way of measuring current on 1 phase of the stepper motor?  A current waveform will show us a lot, voltage waveforms on stepper motors don't tell us much. 

    Best,

    Jacob

  • 0 in reply to Jacob Thompson
    TI__Mastermind 44785 points

    Hello,

    This behavior is not expected from the driver. We have not encountered this either. That said I have seen such issues if the motor connections to the driver were not made correctly. With an ohmmeter you can identify A1 and A2 & B1 and B2 pairs and mark them. Be sure they are connected to AOUT1,2 and BOUT1,2 correctly. 

    Are the waveforms shown STEP and DIR inputs? We can determine anything using these. Please capture A-phase and B-phase current simultaneously like Jacob mentioned.

    Inconsistent motor spinning may also be possible if it is starved of torque. We can identify this issue by looking at the current waveforms. Thanks.

    Regards, Murugavel