DRV8834 only works at ~400hz. No more, no less

Hi guys. Forgive the chaotic nature of this post I have been up all night trying to get my DRV8834 motor to turn my stepper.

This board works with a DIR and STEP pins. By default it is 1/4 step mode which I am sticking to.

Is my nooby-wisdom correct in assuming that if I can turn a stepper at 400hz, I can turn it at 200hz with no problems? I mean My stepper just won't even move.

I started off using a 50% duty-cycle square wave generator but I noticed it wasn't working. So I made a quick arduino sketch with the AccelStepper library.

As a favour to the court I attached a diode+resistor to measure the voltage spikes on one of the motor rails, connected to the A2 pin. I cycled through speeds, and linked the corresponding Hz. Bare in mind that the motor only vibrates, not turns, until I'm around 400hz. I am concerned about how those reported hz on the motor voltage rails arent a simple multiple/fraction of step speed.

I am powering the motor with two 18650 batteries in parallel. The motor is a sy35st28-0504a which says 10V, 500mA.
I have a 100uF electrolytic capacitor + a teeny weeny ceramic capacitor on the VMOT pin to GND.

Now I have used the exact same motor with a different board (that dumb H-Bridge one) with complete success with two 18650s in parallel @ 800hz and every speed below. Actually come to think that might have been series (8v). Hrm uh oh.

4v versus 8v. hrm.

Have I been barking up the wrong decision tree? Its the batteires, right? The batteries pushing out 4v aren't enough to push the motor, right? Hrm I will try again and maybe mark my own thread as solved & hang my head in shame. I welcome everyones feedback and/or witty remarks at my expense.

DRV8834 datasheet:

Pololu DRV8834 guide:

step speed vs motor hz.txt (3.69 KB)

I am powering the motor with two 18650 batteries in parallel.

You should not expect reasonable performance from a 10V high impedance stepper, using a ~3.6V motor power supply.

To what value did you set the motor driver current limit?

its at its default which i cant quite figure out how to set it :confused:

normally i power this motor with a 2x2 pack of 18650s and its plenty. i'm gonna try with 2x2 now. i might 3d print me a chassy to hold these things.

its at its default which i cant quite figure out how to set it :confused:

The Pololu folks make great effort to communicate those extremely important details to their customers, including posting a video presentation of how to set the current limit, right on the product page you linked.

How could you possibly have missed that?