#include <LiquidCrystal.h>

LiquidCrystal lcd(12, 11, 10, 9, 8, 7);

const int echoPin = 2; // pin D2 attached to ECHO
const int trigPin = 3; // pin D3 attached to TRIG

long duration; // duration of sound wave travel
int distance; // distance measurement


void setup() {
  // put your setup code here, to run once:
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);

  // Resets LCD
  lcd.begin(16, 2); 

  lcd.print("Hello        world!");
  lcd.setCursor(0, 1);
  lcd.print("Display demo.");
  delay(1000);

  lcd.begin(16, 2);
  lcd.print("Distance:");
  //Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:

  // Clears the trigPin condition
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);

  // Sets trigPin to HIGH (ACTIVE) for 10 microseconds
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  // Reads the echoPin, returns the sound wave travel time in microseconds
  duration = pulseIn(echoPin, HIGH);

  // Calculating distance & speed of sound wave divided by 2 (go and back)
  distance = duration * 0.034 / 2;

  // Displays distance on LCD 
  lcd.setCursor(0, 1);
  lcd.print(distance);
  lcd.print(" cm    ");

  // Displays distance on Serial Monitor
  //Serial.print("Distance: ");
  //Serial.print(distance);
  //Serial.println(" cm");
}