Basics of GSM Module

If you just started your work on GSM modules and you have no idea where to start then this article is right for you. I will give you step by step details on the basics of GSM modules. But first of all I should build your interest to work on GSM modules. Here are some applications where GSM modules can be used.

GSM Module (GSM Basics)
Figure 1: Basic GSM Module

Smart Homes

To make your home smart you can use  GSM modules as a communication medium. You can control all your electrical Appliances through the module. For security purpose, you can use these modules as well. For example if you want to get a message on your cell phone whenever someone crosses specified doors then GSM module is your best option.

Smart Grids

Smart Grids are new emerging concept in power engineering in which automatic meter reading, demand scheduling etc are included.  Many countries are using GSM modules for implementing smart grids. In many places, power engineers are using smart energy meters which are also based on GSM. If you want to study completely about smart energy meters then click the link below:

Smart Energy Meter using Atmel AVR Microcontrollers


Many industries are also using GSM modules for alarming purposes. For example if you want to get a message when the temperature or humidity level of some area increased by some threshold value then this module can do your work easily.

What is GSM module?

A GSM module is a combination of “GSM IC” and some interfacing circuitry. This GSM IC is same as the GSM IC present in your cell phone. The examples for GSM IC are SIM300, SIM900, SIM900D etc.

Note: Your cell phone is very good example of GSM module but we cannot interface your mobile to the microcontroller because the manufacturer locked those IC for security reasons. There are some old mobile phones which can interface with microcontrollers.

In interfacing circuit two things are mandatory, in which one is SIM holder and other is antenna.

Smallest GSM Module (GSM Basics)
Figure 2: GSM Module with least components

You can see there are only three things are present in this module which are antenna, SIM holder and GSM IC SIM900D. Beside these there may be Audio I/O interface, serial Communications interface present in the module. Keep in mind that there is no difference between GSM module and GSM modem.

Who should learn about GSM?

An electrical, electronics, computer, software and telecommunication engineer should do projects on these modules. A question will come in your mind that why other than telecom engineers should learn GSM. GSM works should be done by telecom engineer only. The answer is while you are working on GSM modules, nobody will ask you to modulate or demodulate signals from tower to tower. You just have to communicate the module with some microcontroller.  Moreover if you are able to turn off or on even a small LED through GSM module then I can assure you that you will fall in love with microcontrollers.

GSM vs. Other Communication Technologies:

There are many other methods through which you can communicate devices. Every method has its own pros and cons. I made a small table for the comparison of these technologies.

Compunication Technologies Comparison
Figure 3: Comparison Table for communication methods

I will focus on only GSM technology here. If we talk about the range of GSM then we can say that it is unlimited. The main advantage of GSM is its range because any place on earth where mobile signals are present is working area of GSM module. I don’t think there are any places left on earth where mobile signals are not present except some special places. So safely I can say that whole earth is the range of GSM. Quite interesting! You can control your room lights from other country as well.

As far as we talk about the speed of GSM it is basically the speed of sending and receiving a text message. It consumes less power than WIFI routers. Moreover controlling of GSM module is not that much difficult.

So we can say that if we need range not speed then GSM is our best option.

Where to start?

Before starting your working on GSM module, I will recommend you to learn serial communication with Atmel AVR Microcontrollers and strings handling. If you are already familiar with these things then you can work on GSM module easily. To make a project on GSM module you just have to connect two wires from module to microcontroller and have to send some AT (Attention) commands from microcontroller to GSM.

If you want to study complete projects on GSM module then click the links below.

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Electrical engineering is my profession, my hobby and my passion. I completed bachelors of electrical engineering in 2015. Currently I am working with a utility company which provides electricity to its consumers. Power Electronics, Embedded Systems and Energy Metering are my fields of specialization. In free time I listen music and watch movies.

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