*Moved from https://github.com/arduino/Arduino/issues/8711 by @Omar-alSuntawi* This code does not work correctly ! ``` const byte ledPin = 13; const byte interruptPin = 2; volatile byte state = LOW; void setup() { pinMode(ledPin, OUTPUT); pinMode(interruptPin, INPUT_PULLUP); attachInterrupt(digitalPinToInterrupt(interruptPin), blink, CHANGE); } void loop() { digitalWrite(ledPin, state); } void blink() { state = !state; } ``` which is on the Arduino Reference [https://www.arduino.cc/reference/en/language/functions/external-interrupts/attachinterrupt/](url) It seems to accidentally read random values.