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Learning Raspberry Pi
Learning Raspberry Pi

Learning Raspberry Pi: Unlock your creative programming potential by creating web technologies, image processing, electronics- and robotics-based projects using the Raspberry Pi

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Profile Icon Serge Schneider Profile Icon Shah
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Full star icon Full star icon Full star icon Full star icon Half star icon 4.7 (3 Ratings)
Paperback Apr 2015 258 pages 1st Edition
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Arrow left icon
Profile Icon Serge Schneider Profile Icon Shah
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$19.99 per month
Full star icon Full star icon Full star icon Full star icon Half star icon 4.7 (3 Ratings)
Paperback Apr 2015 258 pages 1st Edition
eBook
$9.99 $39.99
Paperback
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Free Trial
Renews at $19.99p/m
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Learning Raspberry Pi

Chapter 2. Developing Web Applications

Modern web technologies allow web pages to be used as full-featured applications to replace traditional programs. The most important of these is AJAX, which allows a page to communicate with the server and dynamically alter web page elements. In this chapter, you will learn the basics of web development by creating a simple web page, changing its visual appearance, and making it interactive. Then, you will learn how a web server can serve dynamic pages generated by Python, before putting all of these skills together to create a media player and radio station that you can access from anywhere. We will cover the following topics in this chapter:

  • Adding page content with HTML
  • Customizing the visual appearance
  • Adding interactivity with JavaScript
  • Simplifying scripts with jQuery
  • An introduction to Python
  • Creating an Internet radio station

Getting started with HTML, JavaScript, and jQuery

In the previous chapter, you were introduced to Raspberry Pi and installed LAMP server on your Raspberry Pi. You also installed WordPress to host your personal website/blogs. So, how do you create your blog/website? This section will give a high-level overview of HTML, CSS, JavaScript, and jQuery.

Tip

If you are familiar with HTML, CSS, JavaScript, and jQuery, you might want to jump directly to the An introduction to Python section. You can get the source code from the book website.

Adding page content with HTML

HTML is used by the web browser to display content. To get started, replace /srv/www/index.php with the index.html file, which contains the following code:

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Hello world</title>
</head>

<body>
  <h1>Hello World!</h1>
  <p>This is a <em>simple</em><abbr title=
  ...

An introduction to Python

So far, only the client side of a web application or website has been covered. However, the bulk of the work is usually done on the server, rather than in the browser. Python is an excellent language to handle the backend of web applications and it is very well supported on Raspberry Pi. Moreover, it is the official programming language suggested by Raspberry Pi Foundation. Apart from web development, Python can also be used to develop desktop and command-line applications or games and to the interface of the Raspberry Pi to the real world. This makes it easy to create a web application to display sensor data, or to control the Raspberry Pi.

Python code can be tested directly by running the python command to enter the Python shell. Within the shell, statements can be entered directly. In order to exit the shell, enter quit() or press Ctrl + D. To run the code as a proper program, enter it into a file with the .py extension. The program can then be executed by running...

Creating an Internet radio station

Although the previous example had no practical applications, it introduced most of the concepts needed to make something useful. To put the skills together in a more interesting way, the next example will show you how to create your own Internet radio station. A screenshot of the piMusic interface is shown here:

Creating an Internet radio station

The piMusic interface

The aim is to develop a site to play music stored on your Raspberry Pi from anywhere. This will integrate a small file browser that will allow you to browse your music collection and click a file to play it. Clicking Home will return to the top of the music folder, whereas Up will go up one directory level. Instead of playing individual files, clicking Radio will allow you to play a radio station, which you can manage from your Raspberry Pi.

First, create and enter a directory for the new Flask application as follows:

$ mkdir -p ~/piMusic/static/music
$ mkdir ~/piMusic/templates
$ cd ~/piMusic/templates

Creating the user interface...

Deploying Flask applications

As mentioned earlier, running Flask applications by directly launching the script works for testing, but is extremely unsafe and slow. In order to use nginx as the server for Pi MusicBox, the following needs to be added to the server block of the nginx site's configuration file (/etc/nginx/sites-available/pisite):

location = /piMusic { rewrite ^ /piMusic/; }
location /piMusic { try_files $uri @piMusic; }
location @piMusic {
include uwsgi_params;
    uwsgi_param SCRIPT_NAME /piMusic;
    uwsgi_modifier1 30;
    uwsgi_passunix:/tmp/uwsgi.sock;
}

For consistency, the Pi MusicBox directory should be moved to /srv.

Next, uWSGI needs to be installed and configured. You can think of it as the glue that will connect your application to nginx. You can install it by running this:

# apt-get install uwsgi uwsgi-plugin-python

Then, create the app configuration file /etc/uwsgi/apps-available/piMusic.ini as follows:

[uwsgi]
plugins = python
socket =  /tmp/uwsgi.sock
module...

Summary

In this chapter, an important set of technologies for web development was covered and an application that takes advantage of them was developed. The skills gained here can be used to create rich web applications to control Raspberry Pi and attach hardware remotely.

In the next chapter, you will get introduced to Raspberry Pi electronics and some of the electronics components that you will use later in this book. Using this knowledge, you will develop a digital clock, an e-mail notifier, and an alarm clock.

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Description

If you have a passion for technology and want to explore the world of Raspberry Pi, then this book provides you with all the tools and information you are looking for. Although being familiar with basic programming concepts is useful, you can still learn a lot from this book as a wide variety of topics are covered.

Who is this book for?

If you have a passion for technology and want to explore the world of Raspberry Pi, then this book provides you with all the tools and information you are looking for. Although being familiar with basic programming concepts is useful, you can still learn a lot from this book as a wide variety of topics are covered.

What you will learn

  • Get to grips with the basics of Linux administration, along with the inner workings of Linux distributions
  • Develop a web interface that can be used to upload selected files and create playlists
  • Discover how to connect your Raspberry Pi to the real world using analog inputs
  • Build your own remotecontrolled robot
  • Get to know about different image processing operations
  • Explore troubleshooting tips and tricks
  • Create your own Twitterenabled Raspberry Pi camera

Product Details

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Publication date, Length, Edition, Language, ISBN-13
Publication date : Apr 24, 2015
Length: 258 pages
Edition : 1st
Language : English
ISBN-13 : 9781783982820
Vendor :
Raspberry Pi
Category :
Languages :
Concepts :

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Product Details

Publication date : Apr 24, 2015
Length: 258 pages
Edition : 1st
Language : English
ISBN-13 : 9781783982820
Vendor :
Raspberry Pi
Category :
Languages :
Concepts :

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Table of Contents

8 Chapters
1. Getting Started with Raspberry Pi Chevron down icon Chevron up icon
2. Developing Web Applications Chevron down icon Chevron up icon
3. Introduction to Electronics Chevron down icon Chevron up icon
4. Getting into Robotics Chevron down icon Chevron up icon
5. Introduction to Image Processing Chevron down icon Chevron up icon
6. Image Processing Algorithms Chevron down icon Chevron up icon
7. Troubleshooting, Tips/Tricks, and Resources for Advanced Users Chevron down icon Chevron up icon
Index Chevron down icon Chevron up icon

Customer reviews

Rating distribution
Full star icon Full star icon Full star icon Full star icon Half star icon 4.7
(3 Ratings)
5 star 66.7%
4 star 33.3%
3 star 0%
2 star 0%
1 star 0%
CWJ Koster Jun 01, 2015
Full star icon Full star icon Full star icon Full star icon Full star icon 5
This book just takes you a bit further on what you can do with a Raspberry Pi. It is a great way to learn more and generate ideas on what to make with your Raspberry Pi. The subjects are chosen well and give a broad range of projects. Although the projects are simple they are good starting points for staring your own projects. Learning Raspberry Pi is a good book with lots of information to start experimenting even more with your Raspberry Pi.
Amazon Verified review Amazon
Heleen Durston Jun 06, 2015
Full star icon Full star icon Full star icon Full star icon Full star icon 5
“Learning Raspberry Pi” by Samarth Shah is not the introductory book to the Raspberry Pi that you might think from the title. The book is meant for someone who already has some experience with the device and is looking to expand their knowledge of what’s possible. The book assumes that you have a model B Raspberry Pi and the special camera that was designed especially for the Raspberry Pi which you usually have to buy separately. Additional hardware is required to complete some of the exercises in the book. The book begins by explaining how to set-up your Raspberry Pi and use New Out Of the Box Software (NOOBS) to load the Linux operating system on the device. Once this is done all sorts of wonderful things are possible! Each chapter in the book covers different projects that you can complete with your Raspberry Pi (usually some extra pieces of equipment). The second chapter discusses how you can set-up a web server and create web pages with the Python computer language and Wordpress. By the end of the chapter you can have your own music station running from the Raspberry Pi.The third chapter does a brief explanation of basic electronics and then helps you create your own digital clock and finally an actual alarm clock. This all requires extra parts that you would need to purchase separately. On a side note I got my Raspberry Pi in the form of a kit (many of which are available online) that came with several pieces of extra equipment including diodes, resistors, etc. Most of what you need for the clock is contained within that kit.The fourth chapter covers robotics, one of my favorite aspects of having a Raspberry Pi. The projects in this chapter definitely require you to purchase extra equipment including the special Raspberry Pi camera. Three separate projects are created and then these three are combined together to make a robot. Lots of scripting in Python is required to make each part of the robot work.The next chapter is about image processing and some of the amazing things that can be done with the camera and your Raspberry Pi. The OpenCV image processing software is used to let you manipulate pictures that you capture with the camera. You also learn how to take time-lapsed pictures and how to set-up a Twitter controlled camera.Chapter six dives into software algorithms that can help with the image processing. Details are given on how to set-up facial recognition and even object tracking. So your Raspberry Pi can be set-up to be a surveillance camera of sorts. How cool is that?!! All of this takes patience and determination but is achievable with the details provided in the book.The book ends with some tips for using the Raspberry Pi as well as help with common problems that can occur. Resources for more advanced projects are listed and author provides his email address so that you can tell him of any Raspberry Pi problems you may have.This is a very interesting book and is great for someone who has completed a couple of projects from the Raspberry Pi website. Many hours of enjoyment and learning can be had from following the projects provided in this book.
Amazon Verified review Amazon
Dustin Marx Jun 12, 2015
Full star icon Full star icon Full star icon Full star icon Empty star icon 4
"Learning Raspberry Pi" starts with introductory details regarding Raspberry Pi, but quickly broadens and deepens in its coverage. It provides more lower-level details than one might expect in a "Learning..." book."Learning Raspberry Pi" covers subjects as diverse as Linux commands, web development with Python and HTML5 technologies, a nice introduction to electronics, robotics, and two chapters on image processing. I really liked the final chapter's collection of miscellaneous tips and tricks for dealing with common issues one might run into when working with a Raspberry Pi.Although "Learning Raspberry Pi" does provide introductory coverage of these different technologies, it also goes into depth on some of the topics, particularly image processing. On many of the topics, the book provides just enough introductory information to get going on the subject and additional research might be warranted for deeper learning. There are several highly detailed projects that illustrate the covered concepts.The images and screen snapshots in "Learning Raspberry Pi" are clear and helpful in understanding the concepts. The code listings are comprehensive and are black text on white background with no line numbers and no color syntax.
Amazon Verified review Amazon
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