// definimos pines de direcion y step para el motor
const int stepPin = 4;
const int dirPin = 5; 

int cm, retraso; // Defines variables a utilizar 

long tiempo(int triggerPin, int echoPin) //funcion para retonar el tiempo del HC-SR04
{
  pinMode(triggerPin, OUTPUT);  // Clear the trigger
  digitalWrite(triggerPin, LOW);
  delayMicroseconds(2);
  // Sets the trigger pin to HIGH state for 10 microseconds
  digitalWrite(triggerPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(triggerPin, LOW);
  pinMode(echoPin, INPUT);
  // Reads the echo pin, and returns
  // the sound wave travel time in microseconds
  return pulseIn(echoPin, HIGH);
}

float speedUp() {   //funcion para calcular a que velocidad gira el motor
  cm = 0.0344/2 * tiempo(3, 2);// convertimos el tiempo obtenido a cm
  int vel = map(cm, 0, 400, 4000, 300); //mapeo de distancia a retraso del motor
  return vel;
}

void setup() {
  // Sets the two pins as Outputs
	Serial.begin(9600);
  pinMode(stepPin,OUTPUT);
  pinMode(dirPin,OUTPUT);
  digitalWrite(dirPin,HIGH); //Enables the motor to move in a particular direction
}
void loop() {
  
  retraso = speedUp(); // Gets custom delay values from the custom speedUp function
  // Makes pules with custom delay, depending on the Potentiometer, from which the speed of the motor depends
  Serial.println(retraso); 
  digitalWrite(stepPin, HIGH);
  delayMicroseconds(retraso);
  digitalWrite(stepPin, LOW);
  delayMicroseconds(retraso);
}