Stepper Motor Knob

Stepper motors, due to their unique design, can be controlled to a high degree of accuracy without any feedback mechanisms. The shaft of a stepper, mounted with a series of magnets, is controlled by a series of electromagnetic coils that are charged positively and negatively in a specific sequence, precisely moving it forward or backward in small "steps".

There are two types of steppers, Unipolars and Bipolars, and it is very important to know which type you are working with. For each of the motors, there is a different circuit. The example code will control both kinds of motors. See the unipolar and bipolar motor schematics for information on how to wire up your motor.

In this example, a potentiometer (or other sensor) on analog input 0 is used to control the movement of a stepper motor using the Arduino Stepper Library. The stepper is controlled by with digital pins 8, 9, 10, and 11 for either unipolar or bipolar motors.

The Arduino board will connect to a U2004 Darlington Array if you're using a unipolar stepper or a SN754410NE H-Bridge if you have a bipolar motor.

Hardware Required

  • Arduino Board

  • 10k ohm potentiometer

  • stepper motor

  • U2004 Darlington Array (if using a unipolar stepper)

  • SN754410ne H-Bridge (if using a bipolar stepper)

  • power supply appropriate for your particular stepper

  • hook-up wires

  • breadboard


Below you'll find circuits for both unipolar and bipolar steppers. In either case, it is best to power your stepper motors from an external supply, as they draw too much to be powered directly from your Arduino board.

In both circuits, connect a 10k pot to power and ground, with it's wiper outputting to analog pin 0.

Note: Both circuits below are four wire configurations. Two wire configurations will not work with the code provided.

Unipolar Stepper Circuit and schematic

Unipolar Motor Knob Circuit

UnipolarKnob bbsm

image developed using Fritzing. For more circuit examples, see the Fritzing project page

Unipolar Motor Knob Schematic

UnipolarKnob schms

Bipolar Stepper Circuit and schematic

Bipolar Motor Knob Circuit

bipolarKnob bbsm

image developed using Fritzing. For more circuit examples, see the Fritzing project page

Bipolar Motor Knob Schematic

bipolarKnob schms


For both unipolar and bipolar steppers

See also

Last revision 2018/08/23 by SM