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

A controlled shutdown button


The Raspberry Pi should always be shut down correctly to avoid the SD card being corrupted (by losing power while performing a write operation to the card). This can pose a problem if you don't have a keyboard or screen connected (you might be running an automated program or controlling it remotely over a network and forget to turn it off) as you can't type the command or see what you are doing. By adding our own buttons and LED indicator, we can easily command a shutdown and reset, and then start up again to indicate when the system is active.

Getting ready

You will need the following equipment:

  • 3 x DuPont female-to-male patch wires
  • Mini breadboard (170 tie points) or a larger one
  • Push-button switch (momentary close)
  • General-purpose LED
  • 2 x 470 ohm resistors
  • Breadboard wire (solid core)

The entire layout of the shutdown circuit will look as shown in the following figure:

The controlled shutdown circuit layout

How to do it...

  1. Create the shtdwn.py script as follows:
#!/usr...