BiPolar Stepper with easyDriver


There seemed to be a lot of discussion in class on friday about this so I thought I would share my progress so far.
My EasyDriver came in yesterday and I hooked it up to the teensy and my stepper ( ). I just ran the simple AccelStepper example codes from the schmalzhaus website ( ) and I am powering the driver with a 12v 1amp supply

The stepper shaft didn’t move but I did hear some “winding” sounds from the stepper.
I do have it wired right, I measured resistance across the terminals. I then switched out the bipolar stepper for another unipolar one I had on hand -

This stepper works perfectly.

I can turn the bipolar stepper’s shaft when it is not hooked up, but it is difficult. I also adjusted the current on the EasyDriver to it is delivering the max 75mA. Still the shaft will not budge.

So that is where I am at right now.
Questions: Perhaps the EasyDriver can not deliver enough voltage/amps to the motor to get it to turn?
I am running the Driver in 3.3v mode (to be compatible with the Teensy), perhaps this is the cause?

Maybe the motor is broken?

Hope other people are having better luck



75mA seems really really low … so just to clarify – the unipolar motor is working but the bipolar is not?


yep that is correct.

yea, if 75mA seems low it is because i mistyped. I meant to say 750mA!


So I was able to get the problem motor working.

I took the back plate off to see what was going on inside and when I screwed it back on- the shaft moved much smoother and the motor runs fine now.



Nice find :smile: It’s surprising how much friction resists motion … and in some cases enables it.


I know this isnt the answer but also be careful of the stepping speed, if you step too quickly the shaft wont be able to turn fast enough and you actually will get a whirring noise of the electricity switching phases but no mechanical movement. this is actually semi mitigated by smaller microstepping increments but at full step its pretty easy to have happen