int led=13;
int bouton=12;
int incominbyte=0;
void setup() {
  // put your setup code here, to run once:
pinMode(bouton, INPUT_PULLUP);
Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
int etat=digitalRead(bouton);
incomingByte=Serial.read();
if(etat==LOW)
{Serial.println("le button est appuye");
digitalWrite(led, HIGH);
}
else{
  Serial.println("le button est non appuyé");
  digitalWrite(led, LOW);
}
if(Serial.available()>0)
{
  Serial.print("octet recu: ");
  Serial.println(incomingByte, HEX);
  digitalWrite(led, HIGH);
}
}