Stepper Motor + Arduino

Hardware

There are two basic kinds of stepper motor: unipolar and bipolar. A unipolar stepper motor consists of one coil, or winding, per motor phase with a center tap through which current can flow. If one section of the coils is powered, the motor is in one phase. Power the other section and the motor will switch phase. In this way, the current will not need to switch polarity to operate the motor. This leads to a much simpler control circuit.

A bipolar motor will use one winding per phase. In order to switch motor phase, the polarity of the current going through the windings needs to be reversed. This leads to a more complicated method of controlling the motor.

The motor used in our project (Finding Feanor) was a NEMA 17 bipolar stepper. We used an ITEAD Dual Stepper Motor Driver Shield for Arduino that used two A3967 microstepping driver chips to control the steppers.

Arduino

The Arduino has a convenient library called stepper.h that allows for the control of the motors with several pre-written functions. The complete documentation of the library can be found here.