Ultrasonic

int trig= 7; 
int echo= 6; 
int led= 13;

  void setup() { 
   Serial.begin(9600);
   pinMode(trig, OUTPUT);
   pinMode(echo, INPUT);
   pinMode(led, OUTPUT);
 }

  void loop() {

   digitalWrite(trig, HIGH);
   delayMicroseconds(10);
   digitalWrite(trig, LOW);

    long val= pulseIn(echo, HIGH) * 17 / 100;
   Serial.println(val);

    if(val < 50) { 
    //5cm 범위 안에들어오면 LED  점등 
    digitalWrite(led, HIGH); 
  } else {
     digitalWrite(led, LOW);
   }  

  delay(100);
 }