Raspberry Pi Cookbook, 2nd Edition

Chapter 11. Motors

11.0 Introduction

In this chapter, you will investigate the use of different types of motors with the Raspberry Pi.

11.1 Controlling Servo Motors

Note

Be sure to check out the accompanying video for this recipe at http://razzpisampler.oreilly.com.

Problem

You want to use a Raspberry Pi to control the position of a servo motor.

Solution

Use PWM to control the width of pulses to a servo motor to change its angle. Although this will work, the PWM generated is not completely stable, so there will be a little bit of jitter with the servo. For an alternative solution that produces much more stable pulse timing using the ServoBlaster device driver software, see Recipe 11.2.

If you have an older Raspberry Pi 1, you should also power the servo from a separate 5V power supply because peaks in the load current are very likely to crash or overload the Raspberry Pi. If you have a Raspberry Pi B+ or newer, then improvements in the onboard voltage regulation mean that you may get away with powering small servos directly from the 5V pin on the GPIO port.

Figure 11-1 shows a small 9g servo (see “Miscellaneous”) working quite happily with a Raspberry Pi B+. 

Figure 11-1. Direct connection of a small servo to a Raspberry Pi B+

The leads of the servo are usually 5V wire as red, the ground brown, and the control lead orange. The 5V and ground leads are connected to the GPIO ...