#5.2.3. 초음파 센서

const int trigPin = 9; 

const int echoPin = 10;

void setup() {

  Serial.begin(9600);          

  pinMode(trigPin, OUTPUT);    

  pinMode(echoPin, INPUT);    

}

void loop() {

  digitalWrite(trigPin, LOW);

  delayMicroseconds(2);

  digitalWrite(trigPin, HIGH);

  delayMicroseconds(10);

  digitalWrite(trigPin, LOW);

  long duration = pulseIn(echoPin, HIGH);

  float distance = duration * 0.0343 / 2;

  Serial.print("Distance: ");

  Serial.print(distance);

  Serial.println(" cm");

  delay(1000); 

}