//Import i2C lCD library
#include <LiquidCrystal_I2C.h>
// set the LCD number of columns and rows
int lcdColumns = 16;
int lcdRows = 2;
const int trigPin = 5;
const int echoPin = 18;
long duration;
float distanceCm;
float distanceInch;
const int buzzer = 25;
// set LCD address, number of columns and rows
// if you don't know your display address, run an I2C scanner sketch
//define sound speed in cm/uS
#define SOUND_SPEED 0.034
#define CM_TO_INCH 0.393701
LiquidCrystal_I2C lcd(0x27, lcdColumns, lcdRows);
void setup() {
  // initialize LCD
  lcd.init();
  // turn on LCD backlight
  lcd.backlight();
  Serial.begin(115200); // Starts the serial communication
  pinMode(trigPin, OUTPUT); // Sets the trigPin as an Output
  pinMode(echoPin, INPUT); // Sets the echoPin as an Input
  pinMode(buzzer, OUTPUT);  // Sets buzzer as an Output
}

void loop() {

  // Clears the trigPin
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  // Sets the trigPin on HIGH state for 10 micro seconds
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  // Reads the echoPin, returns the sound wave travel time in microseconds
  duration = pulseIn(echoPin, HIGH);
  // Calculate the distance
  distanceCm = duration * SOUND_SPEED / 2;

  // Convert to inches
  distanceInch = distanceCm * CM_TO_INCH;
  if(distanceCm < 100)
    tone(buzzer, 262, 250);
  else tone(buzzer, 0, 0);

  // Prints the distance in the Serial Monitor
  Serial.print("Distance (cm): ");
  Serial.println(distanceCm);
  Serial.print("Distance (inch): ");
  Serial.println(distanceInch);
  // set cursor to first column, first row
  lcd.setCursor(0, 0);
  // print message
  lcd.print("Distance");
  // set cursor to first column, second row
  lcd.setCursor(0, 1);
  lcd.print(distanceCm);
  lcd.print(" cm");
  delay(1000);
  lcd.clear();
}