#include <LiquidCrystal_I2C.h>

//アドレス0x27 １６文字２行の液晶
LiquidCrystal_I2C lcd(0x27, 16, 2);

void wait_microsec(long wait) {
   long start = micros();
   while (( micros() - start) < wait);
}

void setup() {

  pinMode( 3, INPUT);
  pinMode( 2, OUTPUT);

  lcd.init();
  lcd.backlight();

}

void loop(){

  digitalWrite( 2, HIGH);
  wait_microsec( 11);
  digitalWrite( 2, LOW);
  
  unsigned long range = pulseIn( 3, HIGH ,1000000);
  if ( range ) {
    range = ( ( range * 340) / 2) / 1000;
  
    lcd.setCursor( 0 , 0);
    lcd.print( range / 10 , DEC);
    lcd.print( ".");
    lcd.print( range - ( ( range / 10) * 10) , DEC);
    lcd.print( " cm           ");
  }
  delay( 200);
}