Home security system using PIR sensor and GSM module

In this project, we are going to develop a PIR sensor and GSM based home security system. This project is developed using 8051 microcontroller. It can be used to detect any intrusion in houses and offices and send the alerts on cell phones. Let us know how to develop this system, step by step.

Home security system using PIR sensor and GSM module

Required Components

  • 8051
  • GSM Module
  • PIR Sensor Module
  • LM7805
  • Bread Board
  • LED
  • 1K resistor
  • 10K resistor
  • 1000uf capacitor
  • 10uf capacitor
  • 10K
  • Crystal 11.0592 MHz
  • Power Supply

PIR Sensor

PIR sensors are used to detect living being movement. PIR is a Passive Infrared sensor, which detect infrared rays. All living being with a temperature above absolute zero emits heat energy in the form of radiation. These radiation are infrared ray. Human eye cannot see these rays because these rays are radiated at infrared wavelength. When any living being comes in range of PIR sensor, it detects heat of that living being and generate an output. PIR sensor module does not send any rays for detection, its only detects heat (Infrared). You can know more about PIR sensor in PIR sensor circuit.

GSM Module

The SIM900 is a complete Quad-band GSM/GPRS Module which delivers GSM/GPRS 850/900/1800/1900MHz performance for voice, SMS and Data with low power consumption.

AT Commands

AT commands are used to control GSM module. There are commands for calling and messaging that we have used in this project for sending message. After receiving AT Command GSM Module respond with OK which means GSM module is working fine. Here are some useful commands

ATE0 – For echo off

AT+CMNI=2,2,0,0,0  <ENTER> – Auto opened message Receiving.  (No need to open message)

ATD<Mobile Number>; <ENTER>  – making a call (ATD+919610126059;\r\n)

AT+CMGF=1 <ENTER>   – Selecting Text mode

AT+CMGS=”Mobile Number” <ENTER>   –  Assigning recipient’s mobile number

>> Now we can write our message

>> After writing message

Ctrl+Z  –  send message command (26 in decimal).

ENTER=0x0d in HEX


In this project we have used 8051 microcontroller for controlling the whole process of the project. A PIR sensor is used for sensing human presence. And when PIR sensor sense any movement in targeted area of room then it gives a HIGH logic to microcontroller and then Microcontroller take place and make a call via GSM module using AT commands. Controller calls to a predefined mobile number and at the same time it also sends a message to the same number via GSM Module.

Circuit Diagram

Circuit connections are shown in the above circuit diagram. GSM module’s Rx and Tx pins are directly connected to Tx and Rx pin of  microcontroller And supply by using a 12 Volt adaptor. A PIR Sensor module’s Dout pin is directly connected at pin 21 (P2^0) of Microcontroller with a 10K pull up resistor. A 11.0592 MHz Crystal oscillator is used in this circuit for generating clock signal for microcontroller. And a 5 volt voltage regulator is used for provide 5 volt for the whole circuit.

Source: Home security system using PIR sensor and GSM module

About The Author

Ibrar Ayyub

I am an experienced technical writer holding a Master's degree in computer science from BZU Multan, Pakistan University. With a background spanning various industries, particularly in home automation and engineering, I have honed my skills in crafting clear and concise content. Proficient in leveraging infographics and diagrams, I strive to simplify complex concepts for readers. My strength lies in thorough research and presenting information in a structured and logical format.

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