DRV8834: need help with DRV8834

Hi Rakesh,

One method to control the speed of the stepper motor is to set the CONFIG bit to a logic high. This sets the DRV8834 into indexer mode. Using indexer mode, each step input moves the motor. By increasing and decreasing the frequency of the step input, the motor speed can be increased or decreased.

If you want to control the stepper using Phase/Enable, please see the application report: http://www.ti.com/lit/an/slva416/slva416.pdf

hello sir,

thanks for your quick reply.

i have tried by changing the frequency but still not able to get change speed of stepper motor,can you tell me what can be the problem?

thanks and regards.

hello sir,

i am running my pwm at 572z,with 50% dutycycle.after that i am varying my frequency like 600hz,300hz,400hz,and 800hz. i have checked this with oscilloscope.but still i am not able to vary the speed.i have made config pin to HIGH.i am running motor in indexer mode,
which other factors should i care?where may be the problem?

please help.

thanks

Hi Rakesh,

What is the state of the other inputs when CONFIG is high?
What is the resistance value of the sense resistors?
What are the motor specifications?

If the indexer mode is used, the motor should spin twice as fast with 800Hz than at 400Hz at the STEP input.

hello sir,

thanks for your quick response.

sir right now i dont have any sense resistor connected to my motor,

and when my config pin is high,i have driver in mode32,config pin i have made high by giving 3.2v,

i have attached screen shot of motor's specification.

when  change motor's frequency i observed that motor i not moving and it is just vibrating on same position.

i want to vary the speed of motor.

please reply me.

thanks

Hi Rakesh,

Please let me know state of the other inputs when CONFIG is high and the STEP input is being toggled.

when my  config pin is high and STEP input is  toggled my other input state are.

1)i have microstep 32.

2)rpm 200

3)nENBL/AENBL is low.

and sense resistor is connected to ASEN and BSEN having values of  0.10E both resistors.

hello sir,

do you need any further information from me?

please reply sir.

thanks

Hi Rakesh,

Sorry, my last response did not go through. Please provide the state of the following pins:

AVREF
BVREF
ADECAY
BDECAY

Can you provide scope captures of the STEP input and the current in the A winding and B windings while the motor is attempting to move?

If this is not possible, please provide a scope capture of the STEP input and the voltages on the AISEN and BISEN pins.