Book Image

Mastering Internet of Things

By : Peter Waher
Book Image

Mastering Internet of Things

By: Peter Waher

Overview of this book

The Internet of Things (IoT) is the fastest growing technology market. Industries are embracing IoT technologies to improve operational expenses, product life, and people's well-being. Mastering Internet of Things starts by presenting IoT fundamentals and the smart city. You will learn the important technologies and protocols that are used for the Internet of Things, their features, corresponding security implications, and practical examples on how to use them. This book focuses on creating applications and services for the Internet of Things. Further, you will learn to create applications and services for the Internet of Things. You will be discover various interesting projects and understand how to publish sensor data, control devices, and react to asynchronous events using the XMPP protocol. The book also introduces chat, to interact with your devices. You will learn how to automate your tasks by using Internet of Things Service Platforms as the base for an application. You will understand the subject of privacy, requirements they should be familiar with, and how to avoid violating any of the important new regulations being introduced. At the end of the book, you will have mastered creating open, interoperable and secure networks of things, protecting the privacy and integrity of your users and their information.
Table of Contents (24 chapters)
Title Page
Copyright and Credits
Packt Upsell

Understanding relays

Relays, simply put, are electric switches that we can control using a small output signal. They're perfect for small controllers, like Raspberry Pi, to switch other circuits with higher voltages on and off. The simplest example is to use a relay to switch a lamp on and off. We can't light the lamp using the voltage available to us in Raspberry Pi, but we can use a relay as a switch to control the lamp.

The principal part of a normal relay is a coil. When electricity runs through it, it magnetizes an iron core, which in turn moves a lever from the Normally Closed (NC) connector to the Normally Open (NO) connector. When electricity is cut, a spring returns the lever from the NO connector to the NC connector. This movement of the lever from one connector to the other causes a characteristic clicking sound. This tells you that the relay works. The lever in turn is connected to the Common Ground (COM) connector.

The following figure illustrates how a simple relay is constructed...