#define PIN_TRIG 3
#define PIN_ECHO 2
#define buzzer 5

int distance;
int delayValue;
void setup() {
  Serial.begin(115200);
  pinMode(PIN_TRIG, OUTPUT);
  pinMode(PIN_ECHO, INPUT);
  pinMode(buzzer, OUTPUT);
}

void loop() {
  // Start a new measurement:
  digitalWrite(PIN_TRIG, HIGH);
  delayMicroseconds(10);
  digitalWrite(PIN_TRIG, LOW);

  // Read the result:
  int duration = pulseIn(PIN_ECHO, HIGH);
  // Serial.print("Distance in CM: ");
  // Serial.println(duration / 58);

  distance=duration/58;
  if (distance<30) {
    delayValue=map(distance,0,30,50,500);
    for (int i = 0; i<5 ;i++) {
      digitalWrite(buzzer, HIGH);
      delay(5);
      digitalWrite(buzzer, LOW);
      delay(5);
 }
    delay(delayValue);
  }
}