BeagleBone Cookbook

Chapter 4. Motors

4.0 Introduction

One of the many fun things about embedded computers is that you can move physical things with motors. But there are so many different kinds of motors (servo, stepper, DC), so how do you select the right one?

The type of motor you use depends on the type of motion you want:

R/C or hobby servo motor

Can be quickly positioned at various absolute angles, but some don’t spin. In fact, many can turn only about 180°.

Stepper motor

Spins and can also rotate in precise relative angles, such as turning 45°. Stepper motors come in two types: bipolar (which has four wires) and unipolar (which has five or six wires).

DC motor

Spins either clockwise or counter-clockwise and can have the greatest speed of the three. But a DC motor can’t easily be made to turn to a given angle.

When you know which type of motor to use, interfacing is easy. This chapter shows how to interface with each of these motors.

Note

Motors come in many sizes and types. This chapter presents some of the more popular types and shows how they can interface easily to the Bone. If you need to turn on and off a 120 V motor, consider using something like the PowerSwitch presented in Recipe 3.3.

Note

The Bone has built-in 3.3 V and 5 V supplies, which can supply enough current to drive some small motors. Many motors, however, draw enough current that an external power supply is needed. Therefore, an external 5 V power supply is listed as optional in many of the recipes.

4.1 Controlling ...