#define LED_BUILTIN 13  // deja défini ds arduino.h
#define BP 12

void setup() 
{
  pinMode(LED_BUILTIN, OUTPUT);
  pinMode(BP, INPUT_PULLUP);
//  digitalWrite(LED_BUILTIN, HIGH);
  pinMode(0, OUTPUT);
  pinMode(1, OUTPUT);
}

void loop() {
  if (digitalRead(BP)==1)
      digitalWrite(LED_BUILTIN, HIGH);
  else
      digitalWrite(LED_BUILTIN, LOW);
}