#define smoke A0                     //smoke sensor pin connecetd to pin A0 of Arduino Nano 
 #define Buzzer 8                     //buzzer pin connecetd to pin 8 of Arduino Nano 
 #define LED 13                       //LED pin connecetd to pin 9 of Arduino Nano 
 #define Thres_Val 460                //Threshold value of MQ3 reading should  be trigger
 int value;                           //integer value is define to store the output of MQ3 sensor           
 void setup() {
   pinMode(smoke, INPUT);             //Set MA3 as INPUT device
   pinMode(Buzzer, OUTPUT);           //Set Buzzer as INPUT device
   pinMode(LED, OUTPUT);              //Set LED  as INPUT device
   Serial.begin(9600);
 }
 void loop() {
   value = analogRead(smoke);          // reads the analog value from smoke sensor
   Serial.println(value);
  if ( value > Thres_Val )             //if smoke is detected
   {
     digitalWrite ( LED , HIGH );      // turns the LED on
     digitalWrite(Buzzer,HIGH);        // turns the buzzer on  

 }
 else {
     digitalWrite(LED, LOW);           //  turns the LED off
     digitalWrite(Buzzer,LOW);         //  turns off 
     }
    delay (500);                      
 }