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DRV8884: need Decay Modes selection guidence

JIGAR PATEL2
Intellectual 615 points
Part Number: DRV8884

Hello,

I have successfully operated DRV8884 stepper motor driver with my stepper motor.

Working environment is as below:, Stepper motor datasheet is also attached.

Stepper_Motor.pdf

DRV8884 Power Supply = 12V DC

Stepper motor rated voltage = 12V DC, current = 300mA / phase

Microstepping  = 16

So I have set trip current to 300mA by applying 100K resistor to RREF (pin 16). as per calculation given in datasheet. TRQ is 100%.

 If I am correct for Current setting ?

Now, I am running stepper motor for sucking 40mL liquid  at 150 RPM. This will take around 1.5 sec stepper run time to complete operation.

My question is

I am confused that which decay mode should I use?

I am using 16 microstepping at 150 RPM,  currently i am using following decay mode. 

 

INCREASING STEPS - Mixed decay: 30% fast


DECREASING STEPS - Mixed decay: 30% fast

but how can i decide which decay mode is best for my application?

I am not using any kind of acceleration or deceleration during start / stop.

speed is constant to 150 RPM.

 
Regards,

Jigar 

  • 0
    TI__Genius 14485 points
    Hello Jigar,

    Your RREF resistor looks correct.

    The best way to choose a decay mode is to put a current probe on one of the phases and look at the ripple in your waveform. Try each decay mode, and choose the one with the smallest current ripple. Optimal decay mode setting varies with motor resistance, capacitance, speed, and supply voltage. You'll have to choose the one that works best for your motor. Many designers will also try to choose a decay mode where the motor runs the quietest.
  • 0 in reply to James Lockridge19
    Intellectual 615 points

    Hi James,

    Thanks for the answer.

    OK, I will check the waveform & will decide which decay mode should be set for my application.

    Regards,

    Jigar