low-voltage stepper on the adafruit motor shield

Hi! I have a 2 volt stepper and a adafruit motorshield 2.3 on a arduino uno (image is from another user, but nearly identical to mine) |500x333

I run the "stepper test" program from adafruit, and the stepper chatters: on-off-on-off. It does not complete the rotations that it should. I'm fairly certain that I am tripping some over-volt circut: if you check the FAQ, you see

How many motors can I use with this shield? You can use 2 DC hobby servos that run on 5V and up to 4 DC motors or 2 stepper motors (or 1 stepper and up to 2 DC motors) that run on 5-12VDC

Sadness. My stepper is 2 volts (specs at the bottom). Is there any way I can still safely drive this stepper?

stepper specs:

Manufacturer Part Number 17HS16-2004S1 Step Angle 1.8° Step Accuracy 5% Holding Torque 45Ncm(63.7oz.in) Rated Current/phase 2A Phase Resistance 1.1ohms Voltage 2.2V Inductance 2.6mH±20%(1KHz) Weight 350g

Hmm, maybe I could use a chopper driver?

A Chopper or "Constant Current" drive compensates for the back EMF by driving the motor with a higher voltage. It is not unusual to drive stepper motors at several times their rated voltage using a chopper drive.

To keep things safe at these higher voltages, the chopper drive also monitors the current being delivered to the motor and "chops" it before it exceeds a pre-set level.

A low impedance(*) stepper motor cannot be driven by a standard motor shield, its a different beast and demands current control, not voltage control. Your motor does not have a rated voltage, it has a rated current only. You might run it from 80V if you wanted a fast CNC machine for instance. The key thing is it must have current control - chopper driver is essential.

(*) in practice 5 ohms or less is low impedance, 30 ohms or more is high impedance 12V voltage driven motor, anything in-between is rather pointless, not one thing nor another.

Low impedance motors with chopper drive will give great performance - 5 to 20 times faster is achievable compared to high impedance motor, its a big deal. However you need high voltage supply for most performance - 24V or more is standard, for big CNC setups 80 to 120V isn't unknown.

You may find some useful stuff in Stepper Motor Basics