#define BUTTON_PIN 3
byte lastButtonState = LOW;
unsigned long debounceDuration = 50; // millis
unsigned long lastTimeButtonStateChanged = 0;
void setup() {
  Serial.begin(9600);
  pinMode(BUTTON_PIN, INPUT);
}
void loop() {
  if (millis() - lastTimeButtonStateChanged > debounceDuration) {
      byte buttonState = digitalRead(BUTTON_PIN);
      if (buttonState != lastButtonState) {
      lastTimeButtonStateChanged = millis();
      lastButtonState = buttonState;
      if (buttonState == LOW) {
        // do an action, for example print on Serial
        Serial.println("Button released");
      }
    }
  }
}