const int bouton = 4;
const int led =  2;


int etatBouton = 0;


void setup() {

  pinMode(led, OUTPUT);

  pinMode(bouton, INPUT);
}


void loop(){

  etatBouton = digitalRead(bouton);


  if (etatBouton == LOW) {

    digitalWrite(led, HIGH);
  }
  else {

    digitalWrite(led, LOW);
  }
}