int A = 5;
int B = 4;
int SW = 19;

int anterior = 50;
volatile int posicion = 50;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);

  pinMode(A, INPUT);
  pinMode(B, INPUT);
  pinMode(SW, INPUT);

  attachInterrupt(digitalPinToInterrupt(A), encoder, HIGH);

  Serial.println("Iniciado!");
}

void loop() {
  // put your main code here, to run repeatedly:
  if (posicion != anterior)
  {
    Serial.println(posicion);
    anterior = posicion;
  }
  delay(10); // this speeds up the simulation
}


void encoder()
{
  if (digitalRead(B) == HIGH)
    posicion ++;
  else
    posicion --;
}