#define TRIG_PIN 5
#define ECHO_PIN 18
#define BUZZER_PIN 23
#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27, 16, 2);


void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  pinMode(BUZZER_PIN, OUTPUT);
  lcd.init();
  lcd.backlight();
  lcd.clear();
  lcd.setCursor(0,0);
  lcd.print("Reverse Dist");
  
}

void loop() {
  long duration, distance;
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);
  duration = pulseIn(ECHO_PIN,HIGH);
  distance = duration*0.034/2;
  Serial.print("Distance:");
  Serial.print(distance);
  lcd.setCursor(0, 1);
  lcd.print(distance);
  lcd.print("meters      ");

  if (distance<50 && distance>0){
    long beepDuration = map(distance, 0, 50,50, 500);
    tone(BUZZER_PIN, 1000, beepDuration);
    delay(beepDuration +200);
  }else{
    noTone(BUZZER_PIN);
    delay(500);
  }
  delay(10); // this speeds up the simulation
}