Book Image

Building a Home Security System with BeagleBone

By : William Pretty
Book Image

Building a Home Security System with BeagleBone

By: William Pretty

Overview of this book

One of the best kept secrets of the security industry is just how simple the monitoring hardware actually is - BeagleBone has all the computing power you need to build yourself an extremely sophisticated access control, alarm panel, and home automation and network intrusion-detection system. Security companies make a fortune each year by charging exorbitant fees to their customers. You will learn how easy it is to make an alarm system with Beaglebone. A company-maintained-and-monitored alarm system has its place - your dear old mum is probably not going to be creating her own system any time soon. But if you are reading this book, you are probably a builder or a hobbyist with all the skills required to do it yourself. With Building a Home Security System with BeagleBone, you will learn everything you need to know to develop your own state-of-the-art security system, all for less than a year's worth of monitoring charges from your local alarm company! You will start by building and testing your hardware and open source software on an experimenter's prototype board before progressing to more complex systems. You will then learn how to test your new creations in a modular fashion and begin to utilize BeagleBone. Once your system is built and tested, you will install some of the professional-grade sensors used in modern alarm systems and learn how to use them. You will also discover how to extend your alarm system in a variety of different ways. The only limit will be your imagination.
Table of Contents (16 chapters)

Isolated output PCB


The optically isolated output PCB is a very simple construction. There are two reasons why I made a separate board in this case.

This form factor allows for a more modular design. You can have as many outputs as you can find I/O pins on BeagleBone.

It is also cheaper to order small 3.8" x 2.5" mini boards from ExpressPCB than to order a larger custom-size board.

Isolated output PCB

Assembly of this board is very much the same as that of the first board.

  1. Install the resistors first.

  2. Install the LEDs, making sure that the polarity is correct.

  3. Install the transistors, again checking for correct installation.

  4. Install the ICs preferably on sockets to make repairs easier.

  5. Finally, install the connectors.

Opto-isolated output PCB schematic

All four circuits are identical. A logical 1 on the input applies 3.3V to the base of the NPN transistor. This turns on the transistor and pulls the collector of the transistor low. This turns on the status LED [D1D4] and the LED portion of the 4N35...