Raspberry Pi 3 Projects for Java Programmers

Title Page

Raspberry Pi 3 Projects for Java Programmers

Get the most out of your Raspberry Pi 3 with Java

Pradeeka Seneviratne

John Sirach

       BIRMINGHAM - MUMBAI

Copyright

Raspberry Pi 3 Projects for Java Programmers

Copyright © 2017 Packt Publishing

All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, without the prior written permission of the publisher, except in the case of brief quotations embedded in critical articles or reviews.

Every effort has been made in the preparation of this book to ensure the accuracy of the information presented. However, the information contained in this book is sold without warranty, either express or implied. Neither the authors, nor Packt Publishing, and its dealers and distributors will be held liable for any damages caused or alleged to be caused directly or indirectly by this book.

Packt Publishing has endeavored to provide trademark information about all of the companies and products mentioned in this book by the appropriate use of capitals. However, Packt Publishing cannot guarantee the accuracy of this information.

First published: May 2017

Production reference: 1300517

Published by Packt Publishing Ltd.

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Birmingham 

B3 2PB, UK.

ISBN 978-1-78646-212-1

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Credits

Foreword

About the Authors

Pradeeka Seneviratne is a software engineer with over 10 years of experience in computer programming and designing systems. He is an expert in the development of Arduino and Raspberry Pi-based embedded systems.

Pradeeka is currently a full-time embedded software engineer who works with embedded systems and highly scalable technologies. Previously, he worked as a software engineer for several IT infrastructure and technology servicing companies.

He collaborated on the Outernet (free data from space, forever) project as a volunteer hardware and software tester for Lighthouse, and Raspberry Pi-based DIY Outernet receivers based on Ku band satellite frequencies.

He is also the author of three books:

Internet of Things with Arduino Blueprints by Packt Publishing

IoT: Building Arduino-Based Projects by Packt Publishing

Building Arduino PLCs by Apress

John Sirach works as a product owner at Greenhouse Innovation. He has more than 10 years of experience in Internet-related disciplines from connectivity to hosting, and Internet of Things. Currently, he is involved in the open source PiDome home automation platform project as a passionate Java and JavaFX software developer and project maintainer.

In the past ten years, he has gained experience with large-scale web applications committed to online services with most experience gained in frontend web development and application middleware.

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Table of Contents

Credits

About the Authors

Preface

What this book covers

What you need for this book

Who this book is for

Conventions

Reader feedback

Customer support

Downloading the example code

Downloading the color images of this book

Errata

Piracy

Questions

Setting up Your Raspberry Pi

Getting started with the Raspberry Pi

Getting a compatible SD card

Preparing and formatting the SD card

Installing Raspbian

Configuring Raspbian

Installing Java

Installing and preparing the NetBeans Java editor

Our first remote Java application

Running our application on the Raspberry Pi

Summary

Automatic Light Switch Using Presence Detection

Introduction to and installing Fritzing

Billing of materials

How to emulate reading analog values on digital pins

Starting our project and installing the necessary libraries

The Pi4J libraries

Adding the HD44780-compatible 16x2 character display

Showing data on the HD44780-compatible display

Adding the light-dependent resistor to the setup

Reading and displaying the values from the LDR

Using digital out to switch and display a relay status

Automatic switch based on environment lighting

Using the Bluetooth chip on the Raspberry Pi

Bluetooth device discovery

Putting it all together, our first automation project

Summary

A Social and Personal Digital Photo Frame

Bill of materials

Waveshare HDMI display

Assembling with Raspberry Pi

Selecting video source

Correcting display resolution

Mounting on desktop

Connecting with Flickr

Obtaining a Flickr API key

Creating an album

Finding Flickr photoset_id

REST request format

Invoking flickr.test.echo

Invoking flickr.photosets.getPhotos

Constructing photo source URL

Writing Java program

Accessing Flickr image URL

Installing feh on Raspberry Pi

Scheduling your application

Writing shell script for Java application

Testing the digital_photo_frame.sh with the terminal

Scheduling digital_photo_frame.sh with crontab

Testing digital_photo_frame.sh with crontab

Writing shell script for slideshow

Starting digital photo frame on Raspberry Pi boot

Photo frame in action

Summary

Integrating a Real-Time IoT Dashboard

Adafruit IO

Bill of materials

Sign in with Adafruit IO

Finding your AIO key

Creating news feed

Understanding topics

Creating a dashboard

Creating a block on a dashboard

Raspberry Pi and I2C pins

Connecting an I2C-compatible sensor to the Raspberry Pi

Serial bus addresses

Configuring the Raspberry Pi to use I2C

Searching I2C devices attached to the Raspberry Pi

Accessing I2C with Pi4J

Eclipse Paho Java client

Writing Java program to publish data to a feed

Publishing temperature sensor data

Publishing system information

Subscribing to a feed

Creating a toggle button on Adafruit dashboard

Subscribe to the button feed

Controlling an LED from button feed

Summary

Wireless Controlled Robot

Prerequisites

The Zumo chassis kit

Assembling Zumo chassis

Preparing motors to reducing the effects of electrical noise

Attaching Raspberry Pi to Zumo chassis

Building the circuit

Wiring them together

Moving and turning

Moving

Turning

Swing turn

Writing your Java program

Running and testing your Java program

Summary

Building a Multipurpose IoT Controller

Prerequisites

Preparing your Raspberry Pi board

Installing and configuring Jetty servelet engine

Writing your first Java web application

Creating a Maven project from Archetype

Creating a servlet

Copying iot.war file to the Raspberry Pi

Summary

Security Camera with Face Recognition

Raspberry Pi camera module

Connecting the camera module to the Raspberry Pi

OpenCV

Downloading and installing OpenCV on Windows

Creating the Java project

Adding the OpenCV library to your Java project

Downloading and building OpenCV on Raspberry Pi

Working with video

Facial recognition

Build and run

Summary

Preface

As Java becomes widely used on different hardware platforms from computers to embedded devices, Raspberry Pi has no limitations to work with it to gain full power of Java. This book presents some basic to advanced projects that can be used to build Raspberry Pi 3 projects with Java as the core development platform.

What this book covers

Chapter 1, Setting up Your Raspberry Pi, teaches you about the hardware available with Raspberry Pi and how to prepare to utilize it from the installed Java Virtual Machine. Setting up the NetBeans editor to be able to write Java applications, which can be deployed from the editor, including the in-editor, available console to be able to interact with Java applications on Raspberry Pi.

Chapter 2, Automatic Light Switch Using Presence Detection, explains how to perform analogue readings using digital pins, as the Raspberry Pi has no analog reading capabilities. By adding a 16x2 character display, you will visualize these readings. By adding logic to the code, you will be able to determine when someone is present, and in combination with detecting light levels, you will be able to set a relay state that turns a light on or off.

Chapter 3, A Social and Personal Digital Photo Frame, offers comprehensive guidance on building a social and personal digital photo frame with the Raspberry Pi as the heart. Flickr will be used the social media platform to grab a set of images that will be shown, on the display. FEH will be used an X11 image viewer to display images as a slide show with customizable configurations. Some advanced configurations for the Raspberry Pi will be needed to automate the photo frame to connect with Flickr, download images to local storage, display them on screen, and frequently sync local storage with Flickr.

Chapter 4, Integrating a Real-Time IoT Dashboard, presents a real-time IoT dashboard to display sensor data and Raspberry Pi’s system information on it, and control actuators from it. The dashboard will be built with Adafruit IO, in conjunction with the Eclipse Paho Java MQTT library and Pi4J. The IC2 communication protocol will be used to read data from the sensors by enabling the 12C interface on Raspberry Pi.

Chapter 5, Wireless Controlled Robot, introduces the Zumo chassis kit and how to build a Raspberry Pi brain on it with Java and Pi4J. The robot uses two gear motors to rotate the drive wheels, and the Pi4J library allows us to build various moving and turning mechanisms to control the robot. The built-in Wi-Fi module of the Raspberry Pi 3 allows you to connect the robot wirelessly to the computer, in order to execute the commands through SSH with a keyboard.

Chapter 6, Building a Multipurpose IoT Controller, teaches you how to build a simple web-based IoT controller by installing and configuring a Jetty servlet engine on the Raspberry Pi. Pi4J is used to control an LED or any other actuator from the web interface through a local network or from the Internet, by configuring port forwarding on the router.

Chapter 7, Security Camera with Face Recognition, explains how to build a security camera with face recognition using the OpenCV library for Java and the Raspberry Pi camera module. It uses built-in cascade classifiers to detect human faces and highlights them with a square in real-time video.

What you need for this book

The following software and hardware components are essential in order to build all the projects that presented in this book:

Raspberry Pi 3

Micro SD card

HDMI screen or HDMI enabled TV

HDMI to HDMI cable

5V power supply

Breadboard and wires

Raspberry Pi 3 T-Cobbler or male to female jumper wires

Kohm resistors

Hitachi HD44780 16X2 LCD

A device capable of being detected by Bluetooth, such as a mobile phone

Phillips head screw driver

One Zumo Chassis kit (no motors)

Two 100:1 micro metal Gearmotor HP 6V

One H-bridge motor driver - SN754410 breakout board

Aluminum Standoff

Machine screws

Two 0.1µF ceramic capacitors

Four rechargeable NiMH AA batteries

One USB battery pack for Raspberry Pi - 10000 mAh - 2 x 5V outputs

3mm LED

Raspberry Pi camera module with mount

Hookup wires

Who this book is for

This book is suitable for those who have experience in Java application development and are interested in developing applications on the Raspberry Pi development environment. A basic level of Java-based development skills is essential to develop the projects that will be discussed in this book.

Conventions

In this book, you will find a number of text styles that distinguish between different kinds of information. Here are some examples of these styles and an explanation of their meaning.

Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: Let's take a look at the main(String args[]) method.

A block of code is set as follows:

/**

* Run the LCD example.

*/

public final void runExample(){

/// Clear the display

handler.clear();

/// Cursor to home position (0,0)

handler.setHome();

/// Write to the first line.

handler.write(-- RASPI3JAVA --);

/// Create a time format for output

SimpleDateFormat formatter = new SimpleDateFor-

mat(HH:mm:ss);

/// Sets the cursor on the second line at the first posi-

    tion.

handler.setCursor(1, 0);

/// Write the current time in the set format.

handler.write(--- + formatter.format(new Date()) + ---);

}

New terms and important words are shown in bold. Words that you see on the screen, for example, in menus or dialog boxes, appear in the text like this: In the top of the window there are a set of buttons present which when started has the Welcome button selected. On the same level there is a Breadboard button.

Warnings or important notes appear in a box like this.

Tips and tricks appear like this.

Reader feedback

Feedback from our readers is always welcome. Let us know what you think about this book-what you liked or disliked. Reader feedback is important for us as it helps us develop titles that you will really get