Description:

In this project we build a Fire Alarm System using Arduino. Here we are using LM35 Temperature sensor to detect fire, once fire is detected, output can be displayed on 16×2 LCD Display and an SMS is sent to a phone number using GSM Module. Everything is controlled by Arduino UNO.

Circuit Diagram:

Components:

SR. NO.	COMPONENT	PINOUT DIAGRAM	BUY
1	Arduino UNO (Other Arduinos can be used too)	Arduino UNO Pinout Diagram⇗
2	LM35 Temperature Sensor
3	SIM900A GSM Module
4	16×2 LCD Display
5	SIM Card
6	A Phone

Steps and Info:

1. Get correct components as given. You can buy online or offline. I buy electronics components mostly from Amazon.

2. Start connecting the components. If you are new to connecting components in an electronic circuit, then use a Breadboard or you can straight up make connections using Jumper wires but it will create problem when there will be two or more connections needed at one pin (for example two or more different sensors 5V connection to Arduino’s 5V pin). But before soldering components on a PCB or printing a PCB for your circuit, better try using breadboard so that any errors and mistakes can be observed on breadboard and not after soldering. Or do connections in your way.

3. Now after building the circuit, download the Arduino IDE from https://www.arduino.cc/ website.

4. If you are new to Arduino IDE software, then watch this video we made specially for beginners about Arduino IDE.

5. If you know Arduino IDE then straight up copy the code we given and paste it into the Arduino IDE sketch.

6. Connect the Arduino to your Computer/device. Select a proper port, proper Arduino type and whatever other settings are. Here it is Arduino UNO. (If you don’t know what this all is then watch our video: ).

7. Compile the code and Upload it.

8. If any error occurs then try to troubleshoot it by finding/copy-pasting it into our Solve Errors page https://electronicsprojects.in/solve-errors/, or you can straight up paste the error on Internet and you know the rest. Also check if there are no spelling/syntax errors in the code. Compile the code again once to check if errors are fixed. I have given proper connections and code but still nothing is perfect.

9. Once code compiles and uploads smoothly, you can start testing the working of your circuit/project.

10. Keep an active SMS pack on the SIM card you inserted in the GSM module.

11. Now take a lit a match stick and take it near to the LM35 Temperature sensor, as the sensor will detect the increase in temperature due to the fire from the match stick. The 16×2 LCD will give warning and also send and SMS to the phone number which added in the code.

12. If you are not getting output or getting some Alien language on LCD then try different connections, I have mentioned about this in the code.

13. If the GSM module is not turning ON then connect a 12v battery to it.

14. If it doesn’t work then check connections and code. Also you can talk with me and the community through discord. All the links to social is given at the right side of this page.

Program Code:

/* https://www.electronicsprojects.in Fire Alarm System using Arduino, GSM and LM35 Temperature Sensor */

#include <SoftwareSerial.h>
#include<LiquidCrystal.h>
LiquidCrystal lcd(2,3,4,5,6,7); /* If output not came then try this (7,6,5,4,3,2) */
SoftwareSerial mySerial(9, 10);

int sensor=A0;
float temp_read,Temp_alert_val,Temp_shut_val;
int sms_count=0,Fire_Set;


void setup()
{
  pinMode(sensor,INPUT);
  mySerial.begin(9600);   
  Serial.begin(9600);    
  lcd.begin(16,2);  
  delay(500);
}

void loop()
{
CheckFire();
CheckShutDown();
}

void CheckFire()
{
lcd.setCursor(0,0);
lcd.print("Fire Scan - ON");
Temp_alert_val=CheckTemp();
if(Temp_alert_val>45)
{
 SetAlert();
}
}

float CheckTemp()
{
temp_read=analogRead(sensor); 
temp_read=temp_read*5;    
temp_read=temp_read/10;  
return temp_read; 
}

void SetAlert()
{
while(sms_count<3) 
{  
SendTextMessage(); 
}
Fire_Set=1; 
lcd.setCursor(0,1);
lcd.print("Fire Detected");
}

void CheckShutDown()
{
if(Fire_Set==1)
{

Temp_shut_val=CheckTemp();
if(Temp_shut_val<28)
{
lcd.setCursor(0,1);
lcd.print("No Fire");
sms_count=0;
Fire_Set=0;
}}}

void SendTextMessage()
{
  mySerial.println("AT+CMGF=1");   
  delay(2000);
  mySerial.println("AT+CMGS=\"+919999999999\"\r");     /*Add your Smart Phone Number here*/
  delay(2000);
  mySerial.println("Fire Detected");
  delay(200);
  mySerial.println((char)26);
  delay(5000);
   mySerial.println("AT+CMGS=\"+919999999999\"\r");  /*Add your Smart Phone Number here*/
  delay(2000);
  mySerial.println("Fire Detected");
  delay(200);
  mySerial.println((char)26);
  delay(5000);
  sms_count++;
}

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