//Libraries:
#include <LiquidCrystal.h>
LiquidCrystal lcd(7, 8, 9, 10, 11, 12);
//Define HC-SR04 & other variables!
#define echoPin 2 //attach pin D2 Arduino to pin Echo of HC-SR04
#define trigPin 3 //attach pin D3 Arduino to pin Trig of HC-SR04
long duration;     //variable for the duration of sound wave travel
int distance;      //variable for the distance measurement

void setup() {
  //Task, LCD & distance sensor initialization:
  lcd.begin(16, 2);
  pinMode(trigPin, OUTPUT);  //Sets the trigPin as an OUTPUT
  pinMode(echoPin, INPUT);   //Sets the echoPin as an INPUT
}

void loop() {
  //Clears the trigPin condition
  digitalWrite(trigPin, LOW);
  //Sets the trigPin HIGH (ACTIVE) for 10 microseconds
  digitalWrite(trigPin, HIGH);
  digitalWrite(trigPin, LOW);
  //Reads the echoPin, returns the sound wave travel time in microseconds
  duration = pulseIn(echoPin, HIGH);
  //Calculating the distance
  distance = duration * 0.034 / 2; //Speed of sound wave divided by 2 (go and back)
  lcd.setCursor(0, 0);  lcd.print(distance);
  lcd.setCursor(4, 0);  lcd.print("cm");
  delay(1000);
  lcd.clear();
}