#define TRIG_PIN 5
#define ECHO_PIN 18
#define BUZZER_PIN 23
#define LED_PIN 19

// Konstanta tinggi tangki dalam cm
const float TANK_HEIGHT = 50.0; // Tinggi tangki dalam cm
const float WARNING_LEVEL = 10.0; // Batas minimal air dalam cm

void setup() {
  Serial.begin(115200);
  
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  pinMode(BUZZER_PIN, OUTPUT);
  pinMode(LED_PIN, OUTPUT);

  digitalWrite(BUZZER_PIN, LOW);
  digitalWrite(LED_PIN, LOW);
}

void loop() {
  float distance = measureDistance();
  float waterLevel = TANK_HEIGHT - distance; // Menghitung ketinggian air
  
  Serial.print("Ketinggian Air: ");
  Serial.print(waterLevel);
  Serial.println(" cm");

  // Peringatan jika air terlalu rendah
  if (waterLevel <= WARNING_LEVEL) {
    digitalWrite(BUZZER_PIN, HIGH);
    digitalWrite(LED_PIN, HIGH);
  } else {
    digitalWrite(BUZZER_PIN, LOW);
    digitalWrite(LED_PIN, LOW);
  }

  delay(1000);
}

float measureDistance() {
  // Kirim sinyal trigger
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);

  // Hitung durasi echo
  long duration = pulseIn(ECHO_PIN, HIGH);

  // Hitung jarak dalam cm
  float distance = (duration * 0.034) / 2;
  return distance;
}