// constants won't change. They're used here to
// set pin numbers:
const int buttonPin = A0;     // the number of the pushbutton pin
const int potenciometroPin = A1; //potenciometro conectado al pin analigico 0

const int ledPin =  9;      // the number of the LED pin
 int sensorValue = 0; // Variable para almacenar el valor del potenciometro

// variables will change:
int buttonState = 0;         // variable for reading the pushbutton status

void setup() {
  // initialize the LED pin as an output:
  pinMode(ledPin, OUTPUT);
  // initialize the pushbutton pin as an input:
  pinMode(buttonPin, INPUT);
}

void loop(){
  // read the state of the pushbutton value:
  buttonState = digitalRead(buttonPin);

  // check if the pushbutton is pressed.
  // if it is, the buttonState is HIGH:
  if (buttonState == HIGH) {
    sensorValue = analogRead(potenciometroPin); //Lee el pin A0 y guarda su valor
    analogWrite(ledPin, sensorValue/4);         //Los valores de analogRead van de 0 a 1023, los de analogWrite de 0 a 255
  }
  else {
    // turn LED off:
    digitalWrite(ledPin, LOW);
  }
}