If there's a fire in our home, it's vital to detect it; so in the next section, we will create a project that detects fire with a sensor.

In the following image, we see of the fire sensor module:

You can now either copy the code inside a file called Sensor_fire.ino, or just get the complete code from the folder for this project.

We define the variables for our program at the beginning:

int ledPin = 13;             
int inputPin= 2; 
int val = 0;                    

We define the output signals and the serial communication:

void setup() { 
pinMode(ledPin, OUTPUT);       
pinMode(inputPin, INPUT);      
Serial.begin(9600); 
} 

Now we display the value of the digital signal:

void loop(){ 
val = digitalRead(inputPin); 
Serial.print("val : ");   
Serial.println(val); 
digitalWrite(ledPin, HIGH);  // turn LED ON 

Then we compare: If the value detects a high logic state, it turns off the output; if it reads the opposite, it turns on the digital signal; this means that it has detected fire:

if (val == HIGH) {             
  Serial.print("NO Fire detected "); 
  digitalWrite(ledPin, LOW); // turn LED OFF 
} 
else{ 
  Serial.print("Fire DETECTED "); 
  digitalWrite(ledPin, HIGH);   
  } 
} 

When the Arduino board detects fire, it will read 1 in the digital input, which means no fire detection:

If it detects fire, the digital input reads 0 logic from the digital input: