#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd (0x27, 16,2);

#define pinTrig 2
#define pinEcho 3
#define pinLed 1

float jarak;
long echoTime;

float tinggiAir;

void setup()
{
  lcd.init();
  lcd.backlight();
  pinMode(pinTrig, OUTPUT);
  pinMode(pinEcho, INPUT);
  digitalWrite(pinTrig, LOW);
}

void loop()
{
  digitalWrite(pinTrig, HIGH);
  delayMicroseconds(10);
  digitalWrite(pinTrig, LOW);

  echoTime = pulseIn(pinEcho, HIGH);
  jarak = 0.0001*((float) echoTime * 340.0)/2.0;
  tinggiAir = (150 - jarak);

  if(tinggiAir<30){
    digitalWrite(pinLed, HIGH);
  }else{
    digitalWrite(pinLed, LOW);
  }

  lcd.clear();
  lcd.setCursor (0,0);
  lcd.print("Tinggi Air: ");
  lcd.print(tinggiAir);
  lcd.print(" cm");
  delay(500);
}