#include <Wire.h> // Library for I2C communication
#include <LiquidCrystal_I2C.h> // Library for LCD
LiquidCrystal_I2C lcd = LiquidCrystal_I2C(0x27, 16, 2); // Change to (0x27,16,2) for 16x2 LCD.my address is (0x3F)

int trigPin = A0;
int echoPin = A1;

long distance;
long distanceInch;
long duration;

const int buzzerPin = 9;

void setup(){
 pinMode(buzzerPin, OUTPUT);

 lcd.init();
 lcd.backlight();
 pinMode(trigPin, OUTPUT);
 pinMode(echoPin, INPUT);

 lcd.setCursor(6,0);
 lcd.print("O6U");
 lcd.setCursor(0,1);
 lcd.print("Computer science");
 delay(2000);
}

void loop() {
 ULTRASONIC();
 lcd.clear();
 lcd.setCursor(0,0);
 lcd.print("DISTANCE:");
 lcd.print(distance);
 lcd.print(" cm"); 
 lcd.setCursor(0,1);
 
 if(distance >= 16){
  lcd.print("----------------");
  analogWrite(buzzerPin, 127);
  delay(300);
  analogWrite(buzzerPin,0);
  delay(10000);
 }
 else if (distance == 15) {
  lcd.print("==============="); 
} else if (distance == 14) {
  lcd.print("==============");
}else if (distance == 13) {
  lcd.print("============");
}else if (distance == 12) {
  lcd.print("===========");
}else if (distance == 11) {
  lcd.print("==========");
}else if (distance == 10) {
  lcd.print("=========");
}else if (distance == 9) {
  lcd.print("========");
}else if (distance == 8) {
  lcd.print("=======");
}else if (distance == 7) {
  lcd.print("======");
}else if (distance == 6) {
  lcd.print("=====");
}else if (distance == 5) {
  lcd.print("====");
}else if (distance == 4) {
  lcd.print("===");
}else if (distance == 3) {
  lcd.print("==");
}else if (distance == 2) {
  lcd.print("=");
}else if (distance == 1) {
  lcd.print("X");
}

if(distance < 16 && distance >= 10 ){
  analogWrite(buzzerPin, 127);
  lcd.noBacklight();
  delay(300);
  lcd.backlight();
  analogWrite(buzzerPin,0);
  delay(300);
}else if (distance < 10 && distance >= 5 ) {
   analogWrite(buzzerPin, 127);
   lcd.noBacklight();
  delay(300);
  lcd.backlight();
  analogWrite(buzzerPin,0);
  delay(100);
}else if (distance < 5 ) {
   analogWrite(buzzerPin, 127);
   lcd.noBacklight();
  delay(300);
  lcd.backlight();
  analogWrite(buzzerPin,0);
  delay(50);
} 

}
void ULTRASONIC(){
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  duration = pulseIn(echoPin, HIGH);
  distance = duration*0.034/2;
  delay(5);
  }