
void avanza(){
digitalWrite(4, HIGH); digitalWrite(5,LOW);
digitalWrite(6, HIGH); digitalWrite(7,LOW);  
}


void retrocede(){
digitalWrite(5, HIGH); digitalWrite(4,LOW);
digitalWrite(7, HIGH); digitalWrite(6,LOW);  
}
void para(){
digitalWrite(4, LOW); digitalWrite(5,LOW);
digitalWrite(6, LOW); digitalWrite(7,LOW);  
}


void setup() {
  // put your setup code here, to run once:
  pinMode(4, OUTPUT);
  pinMode(5, OUTPUT);
  pinMode(6, OUTPUT);
  pinMode(7, OUTPUT);
  pinMode(9, INPUT);
  pinMode(8, INPUT);

Serial.begin(9600);
  

}

void loop() {
  // put your main code here, to run repeatedly:

  if (digitalRead(9) == HIGH) {
    avanza();
    Serial.println("9");
    delay(500);
  }
  if (digitalRead(8) == HIGH) {
    Serial.println("8");
    delay(500);
    retrocede();
  }
  if ((digitalRead(9) == LOW) &&(digitalRead(8  ) == LOW)) {
   para();
  }
  
}
