// button debouncer

byte buttonPin = 12; // DIO pin for button N.O. pin
int buttonCount;     // count button presses
unsigned long buttonTimer, buttonTimeout = 50; // used in readButton() debounce timer
bool currentButtonState, lastButtonRead; // record button states

void setup() {
  Serial.begin(115200);
  pinMode(buttonPin, INPUT_PULLUP); // pin --> button (n.o.) button --> gnd
  Serial.print("Press yer button on Pin ");
  Serial.print(buttonPin);
  Serial.print(".\nButton count: ");
  Serial.print(buttonCount);
}

void loop() {
  debounceButton();
}

void debounceButton() {
  bool currentButtonRead = digitalRead(buttonPin);              // read button pin

  if (currentButtonRead != lastButtonRead) {                    // if THIS read is not the same as LAST read...
    buttonTimer = millis();                                     // ...start a timer by storing millis()
    lastButtonRead = currentButtonRead;                         // ... and store current state
  }

  if ((millis() - buttonTimer) > buttonTimeout) {               // if button change was longer than debounce timeout (NOT NOISE)
    if (currentButtonState == HIGH && lastButtonRead == LOW) {  // ... and State is "NOT pressed" while Button "IS PRESSED"

      //==================================================      // The button WAS pressed...
      digitalWrite(LED_BUILTIN, HIGH);                          // Do something here...
      Serial.print(++buttonCount);                              // ... an action...
      digitalWrite(LED_BUILTIN, LOW);                           // ... or call functions
      //==================================================

    }
    currentButtonState = currentButtonRead;                     // update button state for first if() condition test
  }
}