#define LEDPIN 9
#define KEYPIN 6
#define DELAY 50
#define PERIODE 5000

static uint8_t xalt = 0;
static uint8_t xneu = 0;
  

void setup() {
  pinMode(LEDPIN, OUTPUT);
  pinMode(KEYPIN, INPUT_PULLUP);
  Serial.begin(9600);
}

void loop() {

  xalt = xneu;
  xneu = digitalRead(KEYPIN);

  if (xalt > xneu) {
    digitalWrite(LEDPIN, !digitalRead(LEDPIN));
  }

  delay(DELAY);
  
}