#define PIN_TRIG 3
#define PIN_ECHO 2
void setup() {
  Serial.begin(115200);
  pinMode(PIN_TRIG, OUTPUT);
  pinMode(PIN_ECHO, INPUT);
  pinMode(4, OUTPUT);
  pinMode(5, OUTPUT);
  pinMode(6, OUTPUT);
  pinMode(7, OUTPUT);
  pinMode(8, OUTPUT);
  pinMode(9, OUTPUT);
  pinMode(10, OUTPUT);
  pinMode(11, OUTPUT);
  pinMode(12, OUTPUT);
  pinMode(13, 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);
  int dist = duration / 58;
  Serial.print("Distance in CM: ");
  Serial.println(dist);

  if (dist > 100) 
  {
      digitalWrite(4, LOW);
      digitalWrite(5, LOW);
      digitalWrite(6, LOW);
      digitalWrite(7, LOW);
      digitalWrite(8, LOW);
      digitalWrite(9, LOW);
      digitalWrite(10, LOW);
      digitalWrite(11, LOW);
      digitalWrite(12, LOW);
      digitalWrite(13, LOW);
  }
  else if (dist < 20)
  {
      digitalWrite(4, HIGH);
      digitalWrite(5, HIGH);
      digitalWrite(6, HIGH);
      digitalWrite(7, HIGH);
      digitalWrite(8, HIGH);
      digitalWrite(9, HIGH);
      digitalWrite(10, HIGH);
      digitalWrite(11, HIGH);
      digitalWrite(12, HIGH);
      digitalWrite(13, HIGH);
   }
  else if (dist < 60)
  {
      digitalWrite(4, HIGH);
      digitalWrite(5, HIGH);
      digitalWrite(6, HIGH);
      digitalWrite(7, HIGH);
      digitalWrite(8, HIGH);
      digitalWrite(9, HIGH);
      digitalWrite(10, HIGH);
      digitalWrite(11, LOW);
      digitalWrite(12, LOW);
      digitalWrite(13, LOW);
   }
   else if (dist < 100)
  {
      digitalWrite(4, HIGH);
      digitalWrite(5, HIGH);
      digitalWrite(6, HIGH);
      digitalWrite(7, LOW);
      digitalWrite(8, LOW);
      digitalWrite(9, LOW);
      digitalWrite(10, LOW);
      digitalWrite(11, LOW);
      digitalWrite(12, LOW);
      digitalWrite(13, LOW);
   }
  delay(10);
}