int led =13;
int buzzer = 8;
int obstacle =7;
int hasobstacle = LOW;
void setup() {
  // put your setup code here, to run once:
  pinMode(obstacle, INPUT);
  pinMode(buzzer, OUTPUT);
  pinMode(led, OUTPUT);
  Serial.begin(9600);

}

void loop() {
  // put your main code here, to run repeatedly:
  hasobstacle = digitalRead(obstacle);
  if(hasobstacle ==HIGH)
  {
    Serial.println("detected");
    tone(buzzer,1000);
    digitalWrite(led, HIGH);
    delay(1000);
  }
  else{
     Serial.println("no detected");
    digitalWrite(led, LOW);
    noTone(buzzer);
    delay(1000);
  }

}