GSM Module (SMS) 2021


GSM Module Features:
1. Sends Theft Alert SMS to Given number.
2. Displays status of system on LCD.
3. Uses PIR Motion sensor
4. Low Cost


What is GSM Technology?

GSM is a mobile communication modem; it stands for global system for mobile communication. This idea was developed at Bell Laboratories in 1970.  It is a widely used mobile communication system in the world.

This is an open and digital cellular technology used for transmitting mobile voice and data services operate at the 850MHz, 900MHz, 1800MHz, and 1900MHz frequency bands.

A GSM module or a GPRS module is a chip or circuit that will be used to establish communication between a mobile device or a computing machine and a GSM or GPRS system.

GSM modem or GSM module is a hardware device that uses GSM mobile telephone technology to provide a data link to a remote network. From the view of the mobile phone network, they are essentially identical to an ordinary mobile phone, including the need for a SIM to identify themselves to the network.

Street crimes are becoming very common nowadays. With the increase in these street crimes, the production of security systems is also increasing in the current century.

A GSM module or a GPRS module is a chip or circuit that will be used to establish communication between a mobile device or a computing machine and a GSM or GPRS system.

What is GSM?

(Global System for Mobile Communications, originally Groupe Spécial Mobile), is a standard developed by the European Telecommunications Standards Institute (ETSI).

It was created to describe the protocols for second-generation (2G) digital cellular networks used by mobile phones and is now the default global standard for mobile communications – with over 90% market share, operating in over 219 countries and territories.

What is GPRS?

General Packet Radio Service (GPRS) is a packet oriented mobile data service on the 2G and 3G cellular communication system’s global system for mobile communications (GSM).

GPRS was originally standardised by European Telecommunications Standards Institute (ETSI) in response to the earlier CDPD and i-mode packet-switched cellular technologies. It is now maintained by the 3rd Generation Partnership Project (3GPP).

What is this GSM Module you speak of?

A module or a GPRS module is a chip or circuit that will be used to establish communication between a mobile device or a computing machine and a GSM or GPRS system. The modem (modulator-demodulator) is a critical part here.

These modules consist of a GSM module or GPRS modem powered by a power supply circuit and communication interfaces (like RS-232, USB 2.0, and others) for computer. A modem can be a dedicated modem device with a serial, USB or Bluetooth connection, or it can be a mobile phone that provides GSM modem capabilities.

The difference between modems, modules and mobiles

A GSM module or GPRS modules are similar to modems, but there’s one difference: A GSM/GPRS Modem is an external equipment, whereas the GSM/GPRS module is a module that can be integrated within an equipment. It is an embedded piece of hardware.

A GSM mobile, on the other hand, is a complete system in itself with embedded processors that are dedicated to provide an interface between the user and the mobile network.



GSM Module
GSM Module

Different types of modern security systems are available in the market that is very efficient and can alert the owner in seconds if an intruder tries to enter the area under surveillance.

These alerts can be in the form of a siren, an alarm or a phone call. These security systems are very expensive and most of the people can not afford them if they want to install it on a small scale like homes.


GSM Module
GSM Module

Home Security Systems are an important feature of modern residential and office setups. Home security systems must be affordable, reliable and effective.

Modern complex home security systems include several security features like fire, intruders, electronic door lock, heat, smoke, temperature, etc. Some security systems may be a combination of all the security measures.

Such complex systems may be expensive and may not be affordable by everyone. There are individual security systems based on the requirement.

In this project, we designed a simple but very efficient home security that has a function of calling the homeowner on his/her mobile number in case of an intruder alert.

The Module communicates with the microcontroller in a serial manner. It has an Rx and Tx pins on the board. These pins are connected to the Tx and Rx pins of the Arduino.

It is important to note that while uploading the program (sketch) to Arduino, the GSM module must be disconnected as it might interfere with the serial communication with the Arduino IDE.

GSM Component Description

PIR Motion Detection Sensor

Passive Infra-Red or PIR Sensor is a Pyroelectric device that detects motion. Hence, it is also called as motion detection sensor. It detects motion by sensing the changes in infrared levels emitted by nearby objects.

GSM Module

GSM Module (SIM 900A)

SIM 900A is the GSM/GPRS module with built in RS232 interface. It has dual band GSM/GPRS system that works on 900/1800MHz frequencies.

With the help of RS232, the modem can be connected to PC or microcontroller via serial cable. Voice calls, SMS and internet access are possible with this module.

There are on board connections for microphone and headphones with which we can make or receive calls.

Arduino UNO

It is the main controller used in this project. It detects the signals from PIR sensor and sends commands to GSM Module accordingly. The serial pins of the Arduino are used in this project to communicate with GSM module.

GSM Module
GSM Module

Working of Arduino GSM Home Security Alarm System

Home Security Alarm Systems are very important in present day society, where crime is increasing. With the technological advancements we have achieved in the recent years, a homeowner doesn’t have to worry about home security while getting off his/her home.

Modern home security systems provide enough security from burglars, fire, smoke, etc. They also provide immediate notification to the homeowner.

The aim of this project is to implement a simple and affordable, but efficient home security alarm system. The project is designed for detecting intruders and informing the owner by making a phone call.

The working of the project is explained below.

GSM Module
GSM Module

PIR sensor detects motion by sensing the difference in infrared or radiant heat levels emitted by surrounding objects. The output of the PIR sensor goes high when it detects any motion. The range of a typical PIR sensor is around 6 meters or about 30 feet.

For proper operation of PIR sensor, it requires a warm up time of 20 to 60 seconds. This is required because, the PIR sensor has a settling time during which it calibrates its sensor according to the environment and stabilizes the infrared detector.

During this time, there should be very little to no motion in front of the sensor. If the sensor is not given enough calibrating time, the output of the PIR sensor may not be reliable.

When the PIR sensor detects any motion, the output of the sensor is high. This is detected by the Arduino. Arduino then communicates with the module via serial communication to make a call to the pre programmed mobile number.

An important point to be noted about PIR sensors is that the output will be high when it detects motion. The output of the sensor goes low from time to time, even when there is motion which may mislead the microcontroller into considering that there is no motion.

This issue must be dealt with in the programming of Arduino by ignoring the low output signals that have a shorter duration than a predefined time. This is done by assuming that the motion in front of PIR sensor is present continuously.

we are using PIR sensor as motion detector module and GSM module will be used to send sms to home owner number whenever motion sensor detect any motion in home.

Owner can switch on this home security module when he is going out for work and switch it off when he/she is inside home. But it is totally dependent on user how he/she wants to use it.

GSM Module
GSM Module

I have included two new features in this project. User can either select call option or message option on his number when he/she detect any motion in home. I will describe it in more detail in later part of this article. So it was the introduction of home security system or motion detection using PIR sensor.

I have used pic microcontroller in this project. If you are new to pic microcontroller programming, I recommend you to check this pic tutorials article, It will help you to get start with pic microcontroller programming for home security system.

1. Sends Theft Alert SMS to Given number.
2. Displays status of system on LCD.
3. Uses PIR Motion sensor
4. Low Cost

This product is very useful for Monitoring home security


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