Hello Raspberry Pi!: Python programming for kids and other beginners

Copyright

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ISBN: 9781617292453

Printed in the United States of America

1 2 3 4 5 6 7 8 9 10 – MAL – 18 17 16 15 14 13

Dedication

To Juliana, Daniel, and John

Brief Table of Contents

Copyright

Brief Table of Contents

Table of Contents

Preface

Acknowledgments

About this book

1. Getting started

Chapter 1. Meet Raspberry Pi

Chapter 2. Exploring Python

2. Playing with Python

Chapter 3. Silly Sentence Generator 3000: creating interactive programs

Chapter 4. Norwegian Blue parrot game: adding logic to programs

Chapter 5. Raspi’s Cave Adventure

3. Pi and Python projects

Chapter 6. Blinky Pi

Chapter 7. Light Up Guessing Game

Chapter 8. DJ Raspi

Appendix A. Raspberry Pi troubleshooting

Appendix B. Raspberry Pi ports and legacy boards

Appendix C. Solutions to chapter challenges

Appendix D. Raspberry Pi projects

Index

List of Figures

List of Listings

Table of Contents

Copyright

Brief Table of Contents

Table of Contents

Preface

Acknowledgments

About this book

1. Getting started

Chapter 1. Meet Raspberry Pi

What is the Raspberry Pi?

Exploring your Raspberry Pi’s parts: hardware

Giving your Pi a cozy home: Pi cases

The brain of your Pi: system on a chip

Connecting a keyboard and mouse: USB ports

Storing memories: your Pi gets a memory card

Connecting a TV or monitor: HDMI port

Other ports and connections

Powering your Pi: microUSB power port

It’s alive! Plugging in the Pi

Getting your Pi running: software

Installing the Raspbian operating system

Configuring the operating system: making it yours

Saving your configuration and rebooting

Getting around: learning Raspbian

Finding and opening applications on your Raspberry Pi

Your files and folders

Writing code

Fruit Picker Extra: shopping at the Pi Store

Challenge

Scavenger hunt

Summary

Chapter 2. Exploring Python

Playing with Python

Discovering Python’s mathematical operators

Adding and subtracting

Multiplying and dividing

Figuring out whole numbers and remainders

Exponents

Square roots

Challenge: stacking Pis!

Storing information using variables

Creating variables and assigning values

Displaying variable values

Storing strings in variables

Changing the value of variables

Displaying text on a screen

Using the print function

Troubleshooting

Creating programs

Writing Python programs with IDLE

Starting a new program

Saving programs

Python interpreting the program

Fruit Picker Extra: creating documents

Writing silly things and saving them

Challenges

The matrix

Building a brick wall

Pi electrons

Summary

2. Playing with Python

Chapter 3. Silly Sentence Generator 3000: creating interactive programs

Creating a welcome message

Starting a new program

Saving the program

Adding notes in your code

Using hashtags for comments

Getting and storing information

Joining strings

Using more than one input

Building the sentence

Troubleshooting

Completing the program: displaying the silly sentence

Fruit Picker Extra: Minecraft Pi

What’s Minecraft?

Launching Minecraft Pi

Python programming interface to Minecraft Pi

Challenges

Knight’s Tale Creator 3000

Subliminal messages

Summary

Chapter 4. Norwegian Blue parrot game: adding logic to programs

Displaying the game introduction

Creating the game welcome message and instructions

Collecting input from the player

Using if statements to respond to users in different ways

Practicing if statements

Using while loops to repeat things

A closer look at while loops

Breaking out of a while loop

Practicing while loops

Using Python code libraries to generate random numbers

Fruit Picker Extra: Scratch

Challenges

Summary

Chapter 5. Raspi’s Cave Adventure

Project introduction: Raspi’s Cave Adventure

Left cave

Right cave

Hey wait, you need a plan (flow diagrams)

Which way should Raspi go? (checking input)

Handling unexpected input

Turning flow diagrams into code

Simplify! Making your own functions

Finishing the left cave

Exploring the right cave

Troubleshooting

Fruit Picker Extra: playing video

Live streaming: exploring from your Pi

Challenges

Introducing dramatic pauses

Random demise

Play again?

Scream!

Summary

3. Pi and Python projects

Chapter 6. Blinky Pi

Setting up your Pi for physical computing

GPIO pins

Breaking out the GPIO pins to a breadboard

Breadboard basics

Building the LED circuit

Step 1. Connect the jumper from GPIO pin 21

Step 2. Add the red LED

Step 3. Connect a resistor

Software: blinkLED program

Running the program

blinkLED: how it works

Adding more LEDs

Building the circuit

Multiple LEDs: program it!

Challenges

Wave pattern

Simon Says

Random blinking

Summary

Chapter 7. Light Up Guessing Game

Guessing Game design

Hardware: building the circuit

Numbers, numbers, numbers!

Wiring an RGB LED

Circuit sketch

Software: LEDGuessingGame program

Setting up the GPIO pins for the RGB LED

Main game loop and logic

Guessing Game Loop and logic

Adding the Play Again Loop and logic

Playing the game

Troubleshooting

Challenges

Game winner

Easter egg

Warmer and colder

Darth Vader surprise

Summary

Chapter 8. DJ Raspi

Project overview

Setting up your Pi to play sounds

OMXPlayer and MP3s

Troubleshooting

Hardware: building the circuit

Wiring a button

Circuit sketch

Adding the second button

Software: the DJ Raspi program

Setting up the Pi: initializing the buttons

Getting a list of sounds

Getting a value of an item stored in a list

Getting the length of a list

Building a list of sound files with the os library

Playing a sound when a button is pressed

Functions!

Testing: your first gig as DJ Raspi

Troubleshooting

Challenges

Double button press surprise

Yoda Magic 8 Ball

Continuing to explore

Summary

Appendix A. Raspberry Pi troubleshooting

Making sure your Pi has power

Checking the connection to your TV or monitor

Pi starts booting up but then stops

Making your Pi a new SD card

Reformatting your SD card

Problems not covered here

Appendix B. Raspberry Pi ports and legacy boards

Raspberry Pi ports

Connecting to a wireless network

3.5 mm audio/video port

Camera Serial Interface: connecting a camera

Ethernet port

TV or monitor connection options

Legacy boards

Raspberry Pi 1 Model B

Raspberry Pi 1 Model B+

Other boards

Appendix C. Solutions to chapter challenges

Chapter 1

Chapter 2

The Matrix

Building a brick wall

Pi electrons

Chapter 3

Knight’s Tale Creator 3000

Subliminal messages

Chapter 4

Rock, Paper, Scissors!

Chapter 5

Introducing dramatic pauses

Random demise

Play again?

Chapter 6

Wave pattern

Simon says

Random blinking

Chapter 7

Game winner

Easter egg

Warmer and colder

Darth Vader surprise

Chapter 8

Double button press surprise

Yoda Magic 8 Ball

Appendix D. Raspberry Pi projects

Halloween heads

Time-lapse photography

Raspberry Pi robot

Index

List of Figures

List of Listings

Preface

In 2013, a parent and friend of mine asked if I would teach a Python course to middle school students at a local school. My friend gently asked if I could somehow use the Raspberry Pi computer in the course. I love learning new things and I had been reading a lot about the Raspberry Pi. So as you can imagine, I was tremendously excited at the opportunity of using it and emphatically said Yes! That event began my journey of developing a course for kids on programming in Python and using the Raspberry Pi and later, this book.

Quickly, as I worked with the Raspberry Pi, I became a disciple of the Raspberry Pi inventors: the best way for kids to learn programming is by giving them an affordable, ready-to-program computer. It was the perfect platform to learn how to program.

As a teacher of computer science, I grew to deeply appreciate Python. I became convinced that it was not only a great programming language, but its focus on readability and simplicity made it perfect for kids to learn as their first programming language.

Fast forward in time—after teaching Python using the Raspberry Pi to many classes of kids, I had developed a set of engaging and funny projects that the kids enjoyed. Just as important, the students learned! The feedback from the kids and the parents was fantastic! Imagine kids rushing to take part in a programming class. It was wonderful!

A few months after developing my course, Nicole Butterfield and Robin de Jongh of Manning Publications contacted me about turning it into a book. I was thrilled at the prospect of bringing the activities and projects from the computer lab into the hands of kids everywhere. What is more, this book would fill an important gap. What I had found when I originally started teaching my course was that there were no books on the Raspberry Pi and programming in Python that were designed for kids. Since the main reason for inventing the Raspberry Pi was to get more kids programming, I was enthusiastic to work on this project.

Nearly two years later, and several versions of the Raspberry Pi later, I’m proud to present this book to the kids and other beginners who want to learn to program. I hope you enjoy using this book and it starts you on your own journey in computer science!

Acknowledgments

Thank you to my wife, Juliana, and our two children, Daniel and John, for their endless support and patience through the long days, nights, and weekends I needed to write this book.

I’d also like to thank Manning Publications for having the vision to pursue this project. In particular, thanks to Robin de Jongh and Nicole Butterfield who kicked off this project by finding and encouraging me; to publisher Marjan Bace for his commitment to me and to this book; to Ozren Harlovic for orchestrating the book review process; to Kevin Sullivan and Mary Piergies for overseeing production; to Chuck Larson for the wonderful work on the graphics; to Tiffany Taylor for her outstanding copyediting; to Alyson Brener for her thorough proofreading; to Candace Gillhoolley and Ana Romac for promoting the book; to technical development editors Donald Bailey, Joel Kotarski, Jeanne Boyarsky, and John Hyaduck; and to Romin Irani, technical proofreader.

This book was significantly improved by my editor at Manning, Dan Maharry, who helped to develop and edit the book from concept to finished product. I’d like to thank Dan for his excellent insights, support, encouragement, and guidance throughout the process.

A big thank you to all the technical reviewers who read the manuscript at various stages of its development and contributed invaluable feedback: Adam Hinden, Antonio Mas Rodriguez, Betsy Hoofnagle, Catherine Freytag, Dr. Christian Mennerich, Dan Kacenjar, David Kerns, Ema Battista, Fanick Atchia, Grace Kacenjar, Henry Freytag, Jaqueline Currie, John Pentakalos, Keenan Hom, Kevin Adjaho Atchia, Matthew Giblin, Nathan Sperry, Odysseas Pentakalos, Sam Kerns, Richard Freytag, Savannah Wilson, and Scott M. King.

Thank you also to all the readers who bought and read the MEAP (Manning Early Access Program) versions of the chapters and who took the time to post comments in the Author Online forum. You helped make this a better book!

The Raspberry Pi Foundation, original inventors, and community deserve a special mention. Thank you for designing something that is helping children to learn computer science. I’d also like to thank Guido van Rossum, the inventor of Python; the Python Software Foundation; and the Python user community, for creating and maintaining a simple and useful programming language for everyone.

About this book

The Raspberry Pi is a small, low-cost computer invented in the U.K. by the Raspberry Pi Foundation. It provides an easy-to-use tool for learning to program in Python. The Raspberry Pi, with its companion memory card, is preloaded with all the software you need to jump into programming in Python. The Raspberry Pi is made for you to learn to code by playing with it. It includes many input and output ports to give you flexibility in how you connect it. Much like a desktop computer, you need to connect a keyboard, mouse, monitor, and power cable to get started.

This book will teach you how to set up your Raspberry Pi, to write programs in Python, and to use your Raspberry Pi and Python to complete some projects. We’ll cover the basics of Python: displaying text, gathering input, repeating commands, creating logic, as well as using the input and output pins of your Raspberry Pi for projects.

This book does not cover advanced Python topics, nor act as a comprehensive reference for Python. Since it is a book for beginners, these topics have been left out for clarity and brevity. If you’d like to learn more Python, there are links to online resources throughout the book.

This book is for kids and other beginners who would like to learn to program. It’s also for kids who have a Raspberry Pi and want to learn what they can do with it. We’ll introduce you to your Raspberry Pi and teach you Python in a natural, playful way, introducing topics and giving you activities to do using your Raspberry Pi. You don’t need to have any prior programming experience. As long as you know how to use a mouse and open up programs by clicking on icons or menu items, you’ll do great.

This book requires a Raspberry Pi, cables, and some other parts to complete the projects and activities. These items are needed throughout the book:

Raspberry Pi 2 Model B

8 GB SD memory card, preloaded with the Raspberry Pi Foundation’s NOOBS (New Out of the Box Software)

USB power supply with micro USB cable (must deliver 1.2 A @ 5 V)

USB keyboard

USB mouse

TV or monitor

Cable to connect to TV or monitor (specific cables for your TV or

monitor are discussed in chapter 1)

To complete the projects in part 3, you’ll also need these parts:

Solderless breadboard

GPIO ribbon cable for the Raspberry Pi 2 Model B (40 pin)

GPIO breakout board

1 dozen jumper wires, male-to-male

1 red LED (light-emitting diode)

1 green LED

1 blue LED

1 red, green, blue (RGB) LED

3 push buttons

3 resistors, 10K ohm

3 resistors, 180 ohm (or between 100 and 300 ohms)

Headphones or powered computer speakers

You can typically find all these items in a Raspberry Pi starter kit or available individually through online retailers and stores that sell the Raspberry Pi, such as CanaKit, Sparkfun, or Adafruit.

Roadmap

This book is divided into three parts.

Part 1 introduces you to the Rasperry Pi, shows you how to set it up, and provides an introduction to the Python programming language:

Chapter 1 provides an overview of the Raspberry Pi and how to set it up for the first time.

Chapter 2 shows you how to write your first Python programs and introduces you to doing math and displaying text with Python.

Part 2 shows you how to build different text-based games while learning how to gather input, display information, make decisions, and repeat instructions in Python:

Chapter 3 teaches you how to create your first interactive Python game, the Silly Sentence Generator 3000, by asking users to type in something and then displaying funny messages to the screen.

Chapter 4 explores how to give your programs logic and use repeating loops as you create a Norwegian Blue Guessing Game.

Chapter 5 demonstrates how to build a Cave Adventure Game, give users multiple choices, check input from users, and create your own Python functions.

Part 3 involves making your Raspberry Pi interact with the world around it:

Chapter 6 explains setting up your Pi with an electronics breadboard, building a simple circuit, and controlling an LED (light) using your Raspberry Pi and Python.

Chapter 7 dives into creating an interactive guessing game that uses lights to respond to a player’s input, letting them know with different colors whether their answer is right or wrong.

Chapter 8 teaches you how to listen to your Pi’s input pins by making a project that combines light and sound to make your own DJ Raspi sound mixer.

Code conventions and downloads

All source code in this book is in a fixed-width font like this, which sets it apart from the surrounding text. In many listings, the code is annotated to point out key concepts. I have tried to format the code so that it fits within the available page space in the book by adding line breaks and using indentation carefully.

The code accompanying this book is hosted at the GitHub repository: https://github.com/rheitz/hello-raspberry-pi. It is also available for download as a zip file from the publisher’s website at www.manning.com/books/hello-raspberry-pi.

Author Online

Purchase of Hello Raspberry Pi! includes free access to a private web forum run by Manning Publications where you can make comments about the book, ask technical questions, and receive help from the author and other users. To access the forum and subscribe to it, point your web browser to www.manning.com/books/hello-raspberry-pi. This Author Online (AO) page provides information on how to get on the forum once you’re registered, what kind of help is available, and the rules of conduct on the forum.

Manning’s commitment to our readers is to provide a venue where a meaningful dialog among individual readers and between readers and the author can take place. It’s not a commitment to any specific amount of participation on the part of the author, whose contribution to the AO remains voluntary (and unpaid). We suggest you try asking the author some challenging questions, lest his interest stray!

The AO forum and the archives of previous discussions will be accessible from the publisher’s website as long as the book is in print.

About the author

Ryan Heitz is a teacher, programmer, maker, father, and big kid. He is the cofounder of Ideaventions, a Science Center for kids, and Ideaventions Academy for Mathematics and Science, a private school focused on science and technology. He specializes in teaching kids how to experience computer science in a fun and engaging way. As a programmer, Ryan has developed software for everything from NASA data collection systems to web mapping applications.

Part 1. Getting started

Get ready to explore Python using your Raspberry Pi! You’ll need a Raspberry Pi and a few other parts and cables for part 1. Here’s your shopping list:

Raspberry Pi 2 Model B

8 GB SD memory card, preloaded with the Raspberry Pi Foundation’s NOOBS (New Out Of the Box Software)

USB power supply with micro USB cable (must deliver 1.2 A @ 5 V)

USB keyboard

USB mouse

TV or monitor

Cable to connect to TV or monitor (specific cables for your TV or monitor are discussed in chapter 1)

Optional item:

Raspberry Pi case

Part 1 will get you on your way to using your Raspberry Pi and launch you into programming it with Python. In chapter 1, you’ll set up your Raspberry Pi, learn how to start (or boot) it up, and then look around inside the Pi’s desktop. Chapter 2 is where you’ll start exploring the Python language. You’ll create your first programs and learn to give instructions to your Raspberry Pi using Python.

By the end of part 1, you’ll know how to get a Raspberry Pi up and running. You’ll be able to write a Python program and interact with your Pi to make it do things like figure out the cost of a cheeseburger meal and display silly messages on the screen.

Chapter 1. Meet Raspberry Pi

In this chapter, you’ll learn how to

Set up your Raspberry Pi

Install an operating system—Raspbian—on your Pi

Find and open applications

Write your first bit of code in Python

What kinds of things do you think you can do with a Raspberry Pi?

1.  Play games.

2.  Watch videos.

3.  Create a video game.

4.  Listen to music.

5.  Make a sound mixer for a dance party.

6.  Build a robot.

Believe it or not, these are all projects you can do yourself, and if you learn to program in Python, the sky is the limit. You can achieve quite a lot on your Pi, as long as you can write a program to do it. But before we talk about that, let’s take a look at a Raspberry Pi and discover what makes it tick.

What is the Raspberry Pi?

The Raspberry Pi, sometimes referred to as the Pi, is a small, low-cost computer invented in the U.K. by the Raspberry Pi Foundation. It provides an easy-to-use tool to help you learn to code in Python (the Pi part of its name came from the focus on using it to code in Python).

About the size of a deck of cards, it isn’t as powerful as a laptop or desktop computer; its computing power is more similar to that of a smart phone. But what it lacks in processing power, it makes up for in its many features:

Its readiness for programming in Python

The many ways you can use it

Its small size and