Home Alarm System- Big Picture

Our team wanted to make our project have a strongly practical application which could prove useful to anyone. With this in mind, we came up with the idea of a home alarm system.

This system is designed to go off when a switch is triggered and then deactivate ONLY when the correct code is entered. The system should also have a on/off switch for turning it on or off before leaving the house. This button will not be able to turn off the system if it is currently alarming. Our home alarm system can be mounted on any door or window and will be triggered to go off when it opens.

Here is our take on a home alarm system.

Home Alarm System – Code

The software for this system implements three states: System Clear, Deactivated, and Alarm Triggered. The code loops while the system is active waiting for the light break sensor to be open indicating that an intruder has broken in. At this point, the code snippet below compares a passcode input by a user to a predefined passcode and acts accordingly. The LCD tells you whether or not the passcode that was entered is correct.

Home Alarm System – Schematics

The circuitry and hardware for our project was rather simple. We had five total buttons, one for on/off toggle and four for the passcode entry. One pin on each button was connected to Vcc on the A3BU and another pin was connected to separate digital pins on the A3BU, then went through a pull down resistor to ground. The passive buzzer has two pins, one connected to the A3BU and one connected to ground. The two LED status lights were connected to ground on one pin, and the other pins were connected to separate pins on the A3BU after going through a resistor. Finally, the photo interrupter had one pin to Vcc, one pin to ground, and the final pin to a digital pin on the A3BU. After the project was functional, we trimmed down the circuit and made it a lot neater. You can see this in the image below. The final image is the circuit schematic for the project.