Book Image

Raspberry Pi 3 Projects for Java Programmers

By : Rajdeep Chandra, John Sirach, Pradeeka Seneviratne
Book Image

Raspberry Pi 3 Projects for Java Programmers

By: Rajdeep Chandra, John Sirach, Pradeeka Seneviratne

Overview of this book

Raspberry Pi is a small, low cost and yet very powerful development platform. It is used to interact with attached electronics by the use of it's GPIO pins for multiple use cases, mainly Home Automation and Robotics. Our book is a project-based guide that will show you how to utilize the Raspberry Pi's GPIO with Java and how you can leverage this utilization with your knowledge of Java. You will start with installing and setting up the necessary hardware to create a seamless development platform. You will then straightaway start by building a project that will utilize light for presence detection. Next, you will program the application, capable of handling real time data using MQTT and utilize RPC to publish data to Further, you will build a wireless robot on top of the zuma chassis with the Raspberry Pi as the main controller. Lastly, you will end the book with advanced projects that will help you to create a multi-purpose IoT controller along with building a security camera that will perform image capture and recognize faces with the help of notifications. By the end of the book, you will be able to build your own real world usable projects not limited to Home Automation, IoT and/or Robotics utilizing logic, user and web interfaces.
Table of Contents (8 chapters)
Integrating a Real-Time IoT Dashboard

Adding the light-dependent resistor to the setup

As mentioned earlier, the Raspberry Pi is unable to read analog values. We are going to add the resistor using a RC circuit, as explained earlier. Here, we need the LDR, capacitor, and a 4.7 Kohm fixed resistor. The fixed resistor is used to make sure that when the LDR is completely saturated, which means that there is no resistance anymore, we won't fry our Raspberry Pi. An extra thing we need to keep in mind is that the Raspberry Pi is a 3.3V device. This means that in this schema, we will be using the 3.3V output because we will be reading the input on the Raspberry Pi pin, which cannot be higher than 3.3V.

Here is an image that shows how to attach this RC circuit to the Raspberry Pi:

Shut down the Raspberry Pi and disconnect the power. Let's first take a quick look at the capacitor. The one we are using is an electrolytic capacitor, which has a positive...