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Hey guys, welcome back to Techatronic.  In today’s blog post we are going to describe how to make GSM based home automation using Arduino as we all are familiar with the automation system. which is widely used in the offices and the home. In this era, the technology upgraded everywhere so we are making this project to aware that we can implement technology into our home and offices, so if you are interested and you have a bit of knowledge in the electronics you can make it easy with the given instructions. we have also made IOT Home automation in our previous article so if you want to make that project you can find it on our website. to make this project work you need to read the full article carefully and the instructions too. Now, let’s start the project with the introduction.

What is GSM based home automation system 

As the name reflect the home automation system is related to the GSM. the automation system which runs on the GSM. like Iot home automation system run over the internet, Bluetooth home automation runs over the Bluetooth. So it is very simple to understand what is GSM home automation system. A system that controls the electronics appliance over the GSM is known as the GSM based home automation system. in this system we control things by our phone message and call. we can trigger the system by call and message. for example, if we store” bulb off ” in the code with the trigger condition and we send the same in the message to the gsm “bulb off” then the connected bulb will turn off. this is home automation with gsm using Arduino. same as we can control the Bulb, Fan, AC, and many more appliances.

How Does it work?

GSM, a global system for mobile communication as the name represents we also use it to control the home appliance. only we need to send a message or a call to triggered the circuit which controls the home appliances. when we send the message to the gsm attached with the Arduino, Arduino read the message by the serial communication and compare the message with the database message if the condition is true the instruction attached to the condition will start to run and if the condition is not true the Arduino checks another condition.  and it will check continuously till the condition will true, the same condition applies for the call. we need to insert a sim card inside the GSM module. always preferred the sim900 module. and 12v , 2amp power supply.

Gsm Based home automation Component required:-

• Arduino Uno
• SIM900
• 12V , 2amp power supply for gsm module
• 4 channel relay
• AC bulb
• Socket
• 220ohm resistor

Gsm Home automation Circuit Diagram:- 

Important notes:-

•   Connect Arduino ground to GSM ground
• Use always 12v , 2amp power supply for gsm

• To on bulb 1 send a message by your phone to gsm “#A.bulb1 on*“
• To off bulb 1 send a message by your phone to gsm “#A.bulb1 off*“
• To on bulb 2 send a message by your phone to gsm “#A.bulb2 on*“
• To on bulb 2 send a message by your phone to gsm “#A.bulb2 off*“
• To on bulb 3 send a message by your phone to gsm “#A.bulb3 on*“
• To on bulb 3 send a message by your phone to gsm “#A.bulb3 off*“

GSM Rx connect to Arduino Tx

GSM Tx connect to Arduino Rx

GSM gnd connect to Arduino gnd

Now we will look into the AT command of GSM Which controls all the instructions.

First, we need to send the AT to check the communication system is working or not. if all the things are right it will get return Ok. otherwise, it may be an error.

+CMGF command is used to set the msg mode in gsm sim900A.

+CMGW is used to store the msg

there is some command given below to use in sim900

Gsm Home automation Arduino Code:-

 // Techatronic.com  
 #define Bulb1 3  
 #define Bulb2 4  
 #define Bulb3 5  
 int temp=0,i=0;  
 int led=8;  
 char str[15];  
 void setup()  
 {  
 Serial.begin(9600);  
 pinMode(led, OUTPUT);  
 pinMode(Bulb1, OUTPUT);  
 pinMode(Bulb2, OUTPUT);  
 pinMode(Bulb3, OUTPUT);  
 digitalWrite(Bulb1,HIGH);  
 digitalWrite(Bulb2,HIGH);  
 digitalWrite(Bulb3,HIGH);  
 Serial.println("AT+CNMI=2,2,0,0,0");  
 delay(500);  
 Serial.println("AT+CMGF=1");  
 delay(1000);  
 }  
 void loop()  
 {  
 if(temp==1)  
 {  
 check();  
 temp=0;  
 i=0;  
 delay(1000);  
 }  
 }  
 void serialEvent()  
 {  
 while(Serial.available())  
 {  
 if(Serial.find("#A."))  
 {  
 digitalWrite(8, HIGH);  
 delay(1000);  
 digitalWrite(8, LOW);  
 while (Serial.available())  
 {  
 char inChar=Serial.read();  
 str[i++]=inChar;  
 if(inChar=='*')  
 {  
 temp=1;  
 return;  
 }  
 }  
 }  
 }  
 }  
 void check()  
 {  
 if(!(strncmp(str,"bulb1 on",8)))  
 {  
 digitalWrite(Bulb1, LOW);  
 delay(200);  
 }  
 else if(!(strncmp(str,"bulb1 off",9)))  
 {  
 digitalWrite(Bulb1, HIGH);  
 delay(200);  
 }  
 else if(!(strncmp(str,"bulb2 on",8)))  
 {  
 digitalWrite(Bulb2, LOW);  
 delay(200);  
 }  
 else if(!(strncmp(str,"bulb2 off",9)))  
 {  
 digitalWrite(Bulb2, HIGH);  
 delay(200);  
 }  
 else if(!(strncmp(str,"bulb3 on",8)))  
 {  
 digitalWrite(Bulb3, LOW);  
 delay(200);  
 }  
 else if(!(strncmp(str,"bulb3 off",9)))  
 {  
 digitalWrite(Bulb3, HIGH);  
 delay(200);  
 }  
 else if(!(strncmp(str,"all on",6)))  
 {  
 digitalWrite(Bulb1, LOW);  
 digitalWrite(Bulb2, LOW);  
 digitalWrite(Bulb3, LOW);  
 delay(200);  
 }  
 else if(!(strncmp(str,"all off",7)))  
 {  
 digitalWrite(Bulb1, HIGH);  
 digitalWrite(Bulb2, HIGH);  
 digitalWrite(Bulb3, HIGH);  
 delay(200);  
 }  
 }  

Upload the given code into your Arduino with Arduino IDE software and if are new to Arduino and don’t know how to upload Arduino Code You can find the tutorial on our website. Thanks and all the best.