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

Writing messages using persistence of vision


Persistence of vision (POV) displays can produce an almost magical effect, displaying images in the air by moving a line of LEDs back and forth very quickly or around in circles. The effect works because your eyes are unable to adjust fast enough to separate out the individual flashes of light, and so you observe a merged image (the message or picture being displayed):

Persistence of vision using RGB LEDs

Getting ready

This recipe uses the RGB LED kit used in the previous recipe; you will also need the following additional items:

  • Breadboard (half-sized or larger)
  • 2 x DuPont female-to-male patch wires
  • Tilt switch (the ball-bearing type is suitable)
  • 1 x 470 ohm resistor (R_Protect)
  • Breadboard wire (solid core)

The tilt switch should be added to the RGB LED (as described in the Getting ready section of the Multiplexed color LEDs recipe). The tilt switch is wired as follows:

The tilt switch is connected to GPIO Input (GPIO pin 24) and Gnd (GPIO pin 6)

To reproduce...