#define pot 0
#define button 3
#define led 9
#define built_in_led 13


int b_state = 0;
int pot_state = 0;

void setup()
{
  pinMode(led, OUTPUT);
  pinMode(built_in_led, OUTPUT);
  pinMode(button, INPUT);
}

void loop()
{
  b_state = digitalRead(button);
  pot_state = analogRead(pot);
  if (b_state == 1)
    analogWrite(led, pot_state);
  else if (b_state == 0)
    digitalWrite(led, LOW);
  if (pot_state > 512)
    digitalWrite(built_in_led, HIGH);
  else if (pot_state < 512)
    digitalWrite(built_in_led, LOW);
}