//Program Water Level
//By Rudi Hidayat, S.Pd., MT
#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27, 16, 2);

int trig = 12;
int echo = 11;
long jarak, durasi;
int buzzer = 2;
int led = 3;

void setup() 
{
  pinMode(trig, OUTPUT);
  pinMode(echo, INPUT);
  Serial.begin(9600);
  pinMode(buzzer, OUTPUT);
  pinMode(led, OUTPUT);
  lcd.init();
  lcd.clear();
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("   WELCOME TO   ");
  lcd.setCursor(0, 1);
  lcd.print("  WATER  LEVEL  ");
  delay(2000);
  lcd.clear();
}

void loop() 
{
  digitalWrite(trig, HIGH);
  delayMicroseconds(5);
  digitalWrite(trig, LOW);
  delayMicroseconds(5);

  durasi = pulseIn(echo, HIGH);
  jarak = durasi / 58.35;

  Serial.print(jarak);
  Serial.println("cm");

  lcd.setCursor(0, 0);
  lcd.print("Jarak =     cm");
  lcd.setCursor(8, 0);
  lcd.print(jarak);

  if (jarak >= 100) {
    tone(buzzer, 1000, 5000);
  }
  else if (jarak < 100) {
    tone(buzzer, 0, 5000);
  }
  delay(100);

  if (jarak >= 100) {
    digitalWrite(led, HIGH);
  }
  else if (jarak <= 20) {
    digitalWrite(led, LOW);
  }
}