#4.6.3.1. 예제 

#include <Wire.h> 

#include <LiquidCrystal_I2C.h>

int trigPin = 9; 

int echoPin = 10;

LiquidCrystal_I2C lcd(0x20, 16, 2);

void setup() {

  pinMode(trigPin, OUTPUT);    

  pinMode(echoPin, INPUT);   

  lcd.begin(16,2);

  lcd.init();            

  lcd.backlight();  

}

void loop() {

  digitalWrite(trigPin, LOW);

  delayMicroseconds(2);

  digitalWrite(trigPin, HIGH);

  delayMicroseconds(10);

  digitalWrite(trigPin, LOW);

  long duration = pulseIn(echoPin, HIGH);

  float distance = duration * 0.0343 / 2;

  lcd.setCursor(0, 0);   

  lcd.print("Dist : ");

  lcd.print(distance); 

  lcd.print("cm");

  delay(1000); 

}