Stepper motor stutters periodically at slow speed

I’m using your stepper motor and driver as shown in the schematic below (until your other driver for 128 microsteps arrives).

At 3 RPM and 16 microsteps, the motor already visibly “stutters” periodically (like twice per second) ever so slightly and this can also be felt when holding the motor; it gets fairly warm with 46,7°C at the required 0,335V. If I adjust the Vref to 0.6V, the “stutter” seems to subside, but the motor then measures 93,8°C : (

Any suggestions how to reach 1 RPM with 32 microsteps? Just in case, I’ve attached a schematic of how things are physically connected.

Many thanks in advance!

Adding a couple of diodes (which generally have a fixed voltage drop) in series with the coils will increase the duty cycle at which the driver operates to provide low currents, which could help. This blog post discusses more about how that works.


Much appreciated!

I will try this non-destructive solution first.

What do you think about the other frequently discussed more permanent hack, supplying pin 19 of the IC with 5V from M2 (M1 and M2 are hardwired for permanent 1/32 microstepping)?

Later, if things still don’t work out well for my case (it’s for an artwork, not a CNC milling machine or 3D printer), I may then think about a 1:2 or “slower” reduction with two wheels and a rubber ring or a toothed belt (where would I find a good selection of these?).

Supplying 5V to pin 19 will put the driver in fast-decay mode, which would probably help, but the exact effects depend on the characteristics of your motor. If you are interested in trying to simulate your system, you might look at this Excel spreadsheet model.

If you are in the United States, McMaster Carr has a large selection of power transmission components like toothed belts and pulleys.


Alright, I best try the nondestructive diode hack first, then the pin 19 hack, then your 1/128 microsteps driver carrier and finally the belt/pulley solution. A round belt pulley could also be beneficial as some kind of slip-clutch to protect the motor to a certain degree, if someone touches the gobo disk.