# How to use a Stepper Motor

## Recommended Posts

Hello!

I have made an Instructable on how to use a stepper motor in unipolar mode.  The code is specifically designed to run the stepper motor with a chipKIT board, but the general principle of how the stepper motor is run can be applied to any system board.  You can check it out here.

Thanks,

James

##### Share on other sites

This question is in regards to the Digilent stepper motor at http://store.digilentinc.com/stepper-motor/. I understand step angle as so many steps per revolution or the number of degrees rotation per step. But I don't understand the feature that lists the step angle of  5.625°/25.  What does "/25" refer to?

Also can you explain the feature - "Moderating ratioL 1/25". I am unfamiliar with this term as well.

##### Share on other sites

Here is some additional information.  The stepper motor I am currently testing measures 1625.5 steps per revolution. Given the motor specifications of +/- 7%, that is within tolerance. Hence as published, the step angle is 5.625/25 degree +/- 7% or 0.225 degrees +/- 7%.  So the steps per revolution can be from 1488 to 1720 and the motor is within tolerance.  The 1625.5 steps per revolution I measured is based on the number of steps to complete 10 revolutions.

I am unsure of the consistency of the step per revolution until I test more motors but I do recommend that each motor be tested before using in a precision position application. I have not resolved the "Moderating ratio" issue.

##### Share on other sites

Hi Flyline,

Truthfully, I have no idea what the "Moderating ratio" is supposed to signify, Google refuses to provide any information about it aside from it being a measurement of how well a material can slow down neutrons, which I'm pretty sure doesn't apply here. That particular specification was pulled from the corresponding datasheet for that stepper motor, available on it's Resource Center.

If I was forced to guess, I suppose it could be a redundant specification to signify the "/25" that is the part of the step angle specification of 5.625/25 degrees. Maybe /25 is an internal gear reduction ratio? You would have 64 discrete steps than are further divided by 25 times through gears so you get a smaller radial rotation distance? Again, this is speculation so I can't vouch for the validity of this.

Thanks,
JColvin