#include <Servo.h>
const int trigPin = 8;
const int echoPin = 7;
int led = 13;
Servo myServo;

void setup() {
  Serial.begin(9600);
  myServo.attach(11);
  pinMode(led, OUTPUT);      
  pinMode(trigPin, OUTPUT);  
  pinMode(echoPin, INPUT);   
  myServo.write(0);        
}
void loop() {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  long duration = pulseIn(echoPin, HIGH);
  long distance = duration * 0.034 / 2;
  Serial.print("distance :");
  Serial.print(distance);
  Serial.print("cm");
  Serial.println();
  if (distance >= 50) {
    digitalWrite(led, LOW);
    myServo.write(90); 
  }
  else {
    digitalWrite(led, HIGH);
    myServo.write(0);
  }
  delay(500);
}