void setup() {
  
  pinMode(D0, OUTPUT);     
  pinMode(D7, OUTPUT);     
  pinMode(D5, INPUT);      
  pinMode(D4, OUTPUT);    
  pinMode(D6, OUTPUT);    
}
void loop() {
  long duration;
  int distance;
  digitalWrite(D4, LOW);
  delayMicroseconds(2);
  digitalWrite(D4, HIGH);
  delayMicroseconds(10);
  digitalWrite(D4, LOW);
  duration = pulseIn(D5, HIGH);
  distance = duration * 0.0343 / 2;
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");
  if (distance < 20) {
    digitalWrite(D0, HIGH);  
    digitalWrite(D7, HIGH);  
    digitalWrite(D6, HIGH);  
  } else if (distance >= 20 && distance < 50) {
    digitalWrite(D0, HIGH);
    digitalWrite(D7, HIGH);
    digitalWrite(D6, LOW);
  } else if (distance >= 50 && distance < 90) {
    digitalWrite(D0, HIGH);
    digitalWrite(D7, LOW);
    digitalWrite(D6, LOW);
  } else {
    digitalWrite(D0, LOW);
    digitalWrite(D7, LOW);
    digitalWrite(D6, LOW);
  }
  delay(1000);  
}