#define POT_PIN A0             //Potentiometer pin at A0
#define BUZZER_PIN 5           //Buzzer pin at digital pin 5
#define RELAY_PIN 9            //Relay pin at digital pin 9
#define RED_LED 13

int alcoholthreshold = 400;    //Assigning threshold alcohol value as 400

void setup() {
  pinMode(POT_PIN, INPUT);
  pinMode(BUZZER_PIN, OUTPUT);
  pinMode(RELAY_PIN, OUTPUT);
  pinMode(RED_LED, OUTPUT);
  digitalWrite(RELAY_PIN, HIGH);  //Engine is initially turned ON
  Serial.begin(9600);
}

void loop() {
  int value =analogRead(POT_PIN);    //Reading the alcohol level value from potentiometer
  Serial.print("Alcohol level = ");
  Serial.println(value);

  if (value>=alcoholthreshold){
    digitalWrite(RELAY_PIN, LOW);
    digitalWrite(BUZZER_PIN, HIGH);
    digitalWrite(RED_LED, HIGH);
    Serial.println("Alcohol detected! Engine locked");
  }
  else {
    digitalWrite(RELAY_PIN, HIGH);
    digitalWrite(BUZZER_PIN, LOW);
    digitalWrite(RED_LED, LOW);
    Serial.println("No alcohol detected");
  }
  delay(200);
}