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DRV8825.

VUNG VO
Prodigy 30 points
Other Parts Discussed in Thread: DRV8825

Set up:  step motor 32 micro steps at 400ma.

I run motor from 200 steps to 600step for each movement  I made.

After each movement   turn off motor  for  power saving.

 

I keep:   Step input is Low and  I set  eNABLE    or  nSLEEP go High.

The motor drop the standby current from 400ma to a few ma.

But the motor arbitrary move out the position;  I just set.

I would like to know? What I'm doing wrong and how to avoid that move

Thank for helping me with the answer.

 

Best regards

  • 0
    TI__Mastermind 26065 points

    Hi Vung

    In all the stepper motor application, we need to keep the winding current of the motor maintainning certain level to achieve the holding torque. In your case, if the set nEnable to HIGH to turn off the motor. the winding current will totally turn off. the motor will move to the full step position because of the natural megnatic restoring force or the load restoring force.

    So, we should keep the current if we want the motor hold still even it is stopped. In order to saving power during holding state, the normal method for stepper is to lower the current to 20%,50% or 70% according to the load condition after stopped. half current is the most common way.

    For DRV8825, you can achieve the half current by setting and lower the AVref and BVref together.

    Thanks.

    Wilson

    Motor Application Team