Arduino Sensor Ketinggian Air

const int pingPin = 7;

// Deklarasi Sensor PING
const int hmax = 5; //5 cm
const int tinggisensor = 150;
int ketinggian;

void setup()
{
  Serial.begin(9600);
}

void loop()
{

  //Baca Ketinggian Air Asusmsi ketinggian sensor ke permukaan 100 cm
  int jarak;
  jarak = bacajarak();
  Serial.print("  Ketinggian: ");
  Serial.println(jarak);
  delay (500);
 }


int bacajarak(){
  int result;
  long duration, cm;
  pinMode(pingPin, OUTPUT);
  digitalWrite(pingPin, LOW);
  delayMicroseconds(2);
  digitalWrite(pingPin, HIGH);
  delayMicroseconds(5);
  digitalWrite(pingPin, LOW);
  pinMode(pingPin, INPUT);
  duration = pulseIn(pingPin, HIGH);
  cm = mmtocm(duration);
  ketinggian = tinggisensor - cm;
  result = ketinggian;
}

long mmtocm(long microseconds)
{
  return microseconds / 29 / 2;
}