#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27,16,2);
int trigPin = 4;
int echoPin = 3;
int duration_us = 0;
int distance_cm = 0;
void setup() {

  lcd.init();
  lcd.backlight();
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
}
void loop() {
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  delayMicroseconds(10);

  duration_us = pulseIn(echoPin,HIGH);
  distance_cm = 0.017*duration_us;

  lcd.clear();
  lcd.setCursor(0,0);
  lcd.print("Distance: ");
  lcd.print(distance_cm);
  lcd.print("cm");
  delay(500);
}