SonarSemprot

int cm = 0;

long readUltrasonicDistance(int triggerPin, int echoPin)
{
  pinMode(triggerPin, OUTPUT);
  digitalWrite(triggerPin, LOW);
  delayMicroseconds(2);
  digitalWrite(triggerPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(triggerPin, LOW);
  pinMode(echoPin, INPUT);
  return pulseIn(echoPin, HIGH);
}

void setup()
{
  pinMode(13, OUTPUT);
  Serial.begin(9600);

}

void loop()
{
  cm = 0.01723 * readUltrasonicDistance(7, 6);
  while (cm <= 50 && cm > 0) {
    digitalWrite(13, HIGH);
    Serial.println("Semprot");
    delay(3000);
    cm = 0;
  }
  digitalWrite(13, LOW);
  Serial.print(cm);
  Serial.println("cm");
  delay(100);
}