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DRV8841 question

Jacky Chen29
Genius 4735 points
Other Parts Discussed in Thread: DRV8825, DRV8841, DRV8880

Hola,

Can DRV8841 do the microstepping with 1/32 like DRV8825？

If not, what's the minimum microstepping of DRV8841？

  • 0
    TI__Mastermind 26065 points

    Hi Jacky,

    For a driver without internal micro-stepping, the device normally can do Full / Half stepping with only the GPIO control to IN/IN or PH/EN interface.

    There are three other ways to do the high level micro-stepping.

    (1). Using external DAC to control Vref_A and Vref_B to do sine current regulation. This method can achieve as high as 1/256 micro-stepping or even higher. The current level is in a close-loop control. Please refer to the following documents of this method.

    http://www.ti.com/lit/an/slva416/slva416.pdf      Basic scheme.

    http://www.ti.com/lit/an/slva641/slva641.pdf      Optimizing.

    (2). Using external PWM input control to the IN/IN or EN/PH interface. This method can also achieve very high-level micro-stepping. But the current is not directly controlled, better for low speed, low inductance stepper motor. Please refer to the following TIDA for this method.

    http://www.ti.com/tool/TIDA-00641 

    (3) Using the AIx and BIx in real time of the stepping. The micro stepping level is based on how many bits of AIx. For example, device like DRV8841 with AI0 and AI1 two bits current control, we can achieve 1/4 micro-stepping. If there is 3 bits, we can achieve 1/8 micro-stepping. This method will need more IO resource from the MCU.

    Anyway, if the current level is in the range, our DRV8880 serials stepper driver will be the best to achieve smooth / fast response micro-stepping.

    Best regards,

    Wilson

  • 0 in reply to Wilson Zuo
    Genius 4735 points

    Hola Wilson,

    What a great answer！Thank you very so so much.

    BTW, I have DRV8825's question as below：

    May I know that Can DRV8825's AVREF and BVREF get up to 3.3V by external divider resistor？

    That's because of our motor needs a bigger torque to drive so it needs increase the current.

    In addition, I will decrease the resistance of ISENA and ISENB.

  • 0 in reply to Jacky Chen29
    TI__Mastermind 26065 points

    Yes. You can get to 3.3v for Vref. But recommand less than 2.5v and bigger than 1v for best perfermance. And the R sense should be smaller so that the voltage drop less than 0.5v.

    Best regards,

  • 0 in reply to Wilson Zuo
    Genius 4735 points
    Hola Wilson,
    Thank you very so much. It's helpful.