# DRV8825 and NEMA 17 Motor

Hey guys,

Ive been working on a project and started setting up the wiring for a NEMA 17 Motor. I read that the Pololu DRV8825 needs to be adjusted for the rated current of the stepper motor. I watched the video but was confused what to set the current limit to if the stepper motor phase current is higher than the continuous current per phase. Below are the specs of the motor and the driver:

[u]NEMA 17[/u] Step Angle: 1.8 Peak Current is 1.68A/phase 4 Wire Bi-Polar 12-24VDC (Recommended)

[u]DRV8825[/u] Minimum operating voltage: 8.2 V Maximum operating voltage: 45 V Continuous current per phase: 1.5 A1 Maximum current per phase: 2.2 A2 Minimum logic voltage: 2.5 V Maximum logic voltage: 5.25 V

From watching the video on the Pololu website would I set the driver to a limit current of 1.68A? Meaning the VREF should be 0.84 V?

Thanks again guys!

Your motor is probably at the margin for what a DRV8825 can deliver. I suggest you set the current limit to 1.68 amps and see how you get on. The DRV8825 will shut itself down if it is overloaded.

You can always set the current limit lower. The motor will run but deliver proportionally less torque.

bnomick: Hey guys,

Ive been working on a project and started setting up the wiring for a NEMA 17 Motor. I read that the Pololu DRV8825 needs to be adjusted for the rated current of the stepper motor. I watched the video but was confused what to set the current limit to if the stepper motor phase current is higher than the continuous current per phase. Below are the specs of the motor and the driver:

There is only one current rating for a stepper, being the maximum current seen by each phase.

MarkT: There is only one current rating for a stepper, being the maximum current seen by each phase.

I believe the OP's confusion is with the two numbers for the driver rather than the motor.

...R

Robin2: I believe the OP's confusion is with the two numbers for the driver rather than the motor.

...R

Correct. I set the VREF to 0.84 Volts and wired it following the diagram on Pololu's website but sadly no luck when trying to run the motor. Double checked the wiring and tested the code on a separate stepper motor that used the BigEasy Driver instead of the DRV8825 and it ran fine... not sure what could possibly be the problem.

bnomick: Correct. I set the VREF to 0.84 Volts and wired it following the diagram on Pololu's website but sadly no luck when trying to run the motor.

What motor current does 0.84 volts equate to?

Make a simple pencil diagram showing how YOU have everything connected and post a photo of the drawing. See this Simple Image Guide

There is always the possibility that your DRV8825 is damaged. Drivers can be destroyed by even a brief disconnection of a wire between the driver and the motor when the driver is powered.

...R