Intruder Detector

/******************************************
  Website: www.elegoo.com

  Time:2017.12.12

 ******************************************/
#include <NewPing.h>
#include <LiquidCrystal.h>

#define TRIGGER_PIN  5  // Arduino pin tied to trigger pin on the ultrasonic sensor.
#define ECHO_PIN     6  // Arduino pin tied to echo pin on the ultrasonic sensor.
#define MAX_DISTANCE 200 // Maximum distance we want to ping for (in centimeters). Maximum sensor distance is rated at 400-500cm.
int buzzer = 3;//the pin of the active buzzer
LiquidCrystal lcd(7,8,9,10,11,13);

NewPing sonar(TRIGGER_PIN, ECHO_PIN, MAX_DISTANCE); // NewPing setup of pins and maximum distance.

void setup() {
  pinMode(buzzer, OUTPUT); //initialize the buzzer pin as an output
  Serial.begin(9600); // Open serial monitor at 9600 baud to see ping results.
  lcd.begin(16, 2);
  lcd.print("Hello World: ");
}

void loop() {
  delay(500);  // Wait 10ms between pings. 10ms should be the shortest delay between pings.
  unsigned int uS = sonar.ping(); // Send ping, get ping time in microseconds (uS).
  Serial.print("Ping: ");
  Serial.print(uS / US_ROUNDTRIP_CM); // Convert ping time to distance and print result (200 = outside set distance range, no ping echo)
  Serial.println("cm");
  
  
  int safetyDistance = uS / US_ROUNDTRIP_CM;

  if (safetyDistance > 1 && safetyDistance <= 186) {
    lcd.setCursor(0, 0);
    lcd.print("Warning: ");
    lcd.setCursor(0, 1);
    lcd.print("Security Breach");
    
   digitalWrite(buzzer, HIGH);
  } else {
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("All Right");
    lcd.setCursor(0, 1);
    lcd.print("");
    digitalWrite(buzzer, LOW);
  }
}