Moving a 2-motors robot with Arduino and a Joystick

// Moving a two motors robot forward with Arduino and a joystick (https://www.sparkfun.com/products/9032)
// by Luca Tringali
//

int dirbpin = 13;
int dirapin = 12;
int speedbpin = 11;
int speedapin = 10;
int hpin = 2; //joystick horizontal axis
int vpin = 3; //joystick vertical axis
int speeda = 0;
int speedb = 0;
int dir = 0;

void setup()
{
pinMode(dirbpin, OUTPUT);
pinMode(dirapin, OUTPUT);
pinMode(speedbpin, OUTPUT);
pinMode(speedapin, OUTPUT);
}

void loop()
{
  // forward, backward
  int vval = analogRead(vpin);
  if (vval > 549) {
    dir = 1;
    vval = map(vval, 550, 1023, 0, 250);
  } else if (vval > 470) {
      vval = 0;
  } else {
    dir = 0;
    vval = map(vval, 470, 0, 0, 250);
  }

  // right, left
  int hval = analogRead(hpin);
  if (hval > 600) {
    speeda = vval;
    speedb = 0;
  } else if (hval > 400) {
    speeda = vval;
    speedb = vval;
  } else {
    speeda = 0;
    speedb = vval;
  }

  digitalWrite(dirapin, dir); // set direction
  analogWrite(speedapin, speeda); // set speed
  digitalWrite(dirbpin, dir); // set direction
  analogWrite(speedbpin, speedb); // set speed
  delay(10);
}


// if you are looking for RC http://abottravel.blogspot.it/2011/12/how-to-read-rc-radio-signals-with.html