#define MQ137 A0              //smoke sensor pin connecetd to pin A0 of Arduino Nano
 #define MQ138 A1 
 #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
 #define flamePin 4
 int Flame = HIGH;
 int value1;                   //integer value is define to store the output of MQ3 sensor
 int value2;
 
  void setup() 
{
   pinMode(MQ137, INPUT);       //Set MA3 as INPUT device
   pinMode(MQ138, INPUT);       //Set MA3 as INPUT device
   pinMode(Buzzer, OUTPUT);     //Set Buzzer as INPUT device
   pinMode(LED, OUTPUT);        //Set LED  as INPUT device
  pinMode(flamePin, INPUT);
  Serial.begin(9600);
}
void mq137() {
   value1 = analogRead(MQ137);           // reads the analog value from smoke sensor
   Serial.println(value);
  if ( value1 > 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);                      
 }
 void mq138() {
   value2 = analogRead(MQ138);           // reads the analog value from smoke sensor
   Serial.println(value);
  if ( value2 > 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);                      
 }


void flamesensor() 
{
  Flame = digitalRead(flamePin);
  if (Flame== LOW)
  {
    digitalWrite(buzzerPin, HIGH);
    digitalWrite(LED , HIGH);
  
  }
  else
  {
    digitalWrite(buzzerPin, LOW);
    digitalWrite(LED , HIGH);
  }
}
void loop(){
  }