1. Introduction

How you connect a stepper motor to a stepper motor driver or controller depends on the type of stepper motor you have. When working with stepper motors, you will typically encounter two types: unipolar and bipolar.

• Unipolar stepper motors have two windings per phase, allowing the magnetic field to be reversed without having to reverse the direction of current in a coil with unipolar drivers. They typically have five leads. It is not possible to control a 5-lead unipolar stepper motor with a bipolar driver.
• Bipolar stepper motors have a single coil per phase and require more complicated control circuitry (typically an H-bridge for each phase). They typically have four leads, two for each coil.
• Unipolar/bipolar stepper motors can be wired to either kind of driver. They typically have six or eight leads, and their specifications are typically for operation in a unipolar configuration unless otherwise noted.

All Pololu stepper motor drivers and stepper motor controllers are bipolar drivers that have the circuitry necessary to control a 4-, 6-, or 8-lead stepper motor in a bipolar configuration. There are a few different wiring methods for these motors that each have their own advantages and disadvantages.

Note: This application note assumes the driver outputs are named A1 and A2 for one phase, and B1 and B2 for the other phase. However, this convention is not universal among all stepper motor drivers/controllers. Refer to the product page documentation for your board to check how the outputs are named for your specific driver, and see the driver’s datasheet for more information.