Book Image

Raspberry Pi 3 Cookbook for Python Programmers - Third Edition

By : Steven Lawrence Fernandes, Tim Cox
Book Image

Raspberry Pi 3 Cookbook for Python Programmers - Third Edition

By: Steven Lawrence Fernandes, Tim Cox

Overview of this book

Raspberry Pi 3 Cookbook for Python Programmers – Third Edition begins by guiding you through setting up Raspberry Pi 3, performing tasks using Python 3.6, and introducing the first steps to interface with electronics. As you work through each chapter, you will build your skills and apply them as you progress. You will learn how to build text classifiers, predict sentiments in words, develop applications using the popular Tkinter library, and create games by controlling graphics on your screen. You will harness the power of a built in graphics processor using Pi3D to generate your own high-quality 3D graphics and environments. You will understand how to connect Raspberry Pi’s hardware pins directly to control electronics, from switching on LEDs and responding to push buttons to driving motors and servos. Get to grips with monitoring sensors to gather real-life data, using it to control other devices, and viewing the results over the internet. You will apply what you have learned by creating your own Pi-Rover or Pi-Hexipod robots. You will also learn about sentiment analysis, face recognition techniques, and building neural network modules for optical character recognition. Finally, you will learn to build movie recommendations system on Raspberry Pi 3.
Table of Contents (23 chapters)
Title Page
Copyright and Credits
Dedication
Packt Upsell
Contributors
Preface
Index

Using advanced motor control


The previous driving circuits are not suitable for driving motors in more than one direction (as they only switch the motor on or off). However, using a circuit named an H-bridge, you can switch and control the motor's direction, too.

The switch combinations are shown in the following diagram:

The direction of the motor can be controlled by different switch combinations

Using a different combination of switching, we can change the direction of the motor by switching the positive and negative supply to the motor (SW1 and SW4 activate the motor, and SW2 and SW3 reverse the motor). However, not only do we need four switching devices for each motor, but since the ULN2X03 devices and PiBorg's PicoBorg module can only sink current, equivalent devices would be required to source current (to make up the top section of switches).

Fortunately, there are purpose-built H-bridge chips, such as L298N, that contain the previous circuit inside them to provide a powerful and convenient...