bool            btnState = false;

void setup() {
  Serial.begin(115200);
  pinMode(2, INPUT_PULLUP);
  attachInterrupt(digitalPinToInterrupt(2), fonctionBp, CHANGE  );
}

void loop() {
  unsigned long time;

  time = millis();
  Serial.println(btnState);
}

void fonctionBp () {
  btnState = !btnState;
}