long duration;
float distance;

int T = 9;
int E = 10;
int Buzz = 7;

void setup() {
  Serial.begin(9600);
  pinMode(T, OUTPUT);
  pinMode(E, INPUT);
  pinMode(Buzz, OUTPUT);
}

void loop() {
  digitalWrite(T, LOW);
  delayMicroseconds(2);

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

  duration = pulseIn(E, HIGH);

  distance = duration * 0.034 / 2;

  if (distance <= 30.00)
  {
    digitalWrite(Buzz, HIGH)
    
      delay(2000);
  }
  else {
    digitalWrite(Buzz, LOW);
  }

  Serial.print(distance);
  Serial.println("cm");

  delay(50);
}