#include <LiquidCrystal.h>               //Using the Arduino as the controller device, the library Allows communication with liquid crystal displays (LCDs).
 LiquidCrystal lcd(13,12,A2,A3,A4,A5);    // initialize the library by associating any needed LCD interface pin with arduino uno 

 #define MQ3 A0                    //MQ3 pin connecetd to pin A0 of Arduino Nano 
 #define Buzzer 8                  //buzzer pin connecetd to pin 8 of Arduino Nano 
 #define LED 10                    //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(MQ3, INPUT);            //Set MA3 as INPUT device
   pinMode(Buzzer, OUTPUT);        //Set Buzzer as output device
   pinMode(LED, OUTPUT);           //Set LED  as output device
   lcd.begin(16,2);                // set up the LCD's number of columns and rows:
   lcd.setCursor(0,0);             // to display the values on to the top left of LCD 
   Serial.begin(9600);             //Set a bourdered of 9600 
 }
 void loop() {
   value = analogRead(MQ3);          // reads the analog value from MQ3
   Serial.println(value);

     lcd.setCursor(0,0);             //
     lcd.print("GAS VALUE :");       // display gas 
     lcd.setCursor(0,1);
     lcd.print(value);
     delay(1000);
     
  if ( value > Thres_Val )           //if alcohol is detected
   {
     digitalWrite ( LED , HIGH );    // turns the LED on
     digitalWrite(Buzzer,HIGH);      // turns on (uncomment if buzzer is used) 

 }
 else {
     digitalWrite(LED, LOW);         //  turns the LED off
     digitalWrite(Buzzer,LOW);       //  turns off (uncomment if buzzer is used) 
     }
    delay (500);                     //  a 500ms delay before reading is taken again
 }