Return to Question

What I think is the sequence of events: loop(), loop(), loop(), "loop() button press, start timer", loop(),loop(),loop(),"enough time has passed, but since no reading in this loop(), execute the code we always do (i.e., if(0 != buttonState)).

What I think is the sequence of events: loop(), loop(), loop(), "loop(), button press, reading=1, set lastDebounceTime, first if condition fails because we have to wait, set lastButtonState=1", loop(), loop(),loop(),"loop() enough time has passed, but since no button press at in this iteration and the last few, reading and lastButtonState equal zero", loop(), ... .

However, this code works. My question is: How?

However, this code works.

Why do we save reading in a local variable? Won't the code virtually always be this, then:

if (reading != lastButtonState) {
    // reset the debouncing timer
    lastDebounceTime = millis();
  }

  if ((millis() - lastDebounceTime) > debounceDelay) {
    // whatever the reading is at, it's been there for longer than the debounce
    // delay, so take it as the actual current state:

    // if the button state has changed:
    if 0 != buttonState) {
      buttonState = 0;

...

Entire code:

I don't understand the following Debounce code. (The complete code is at the bottom.) From what I understand, when the pin reads something, we wait at least 50 milliseconds before performing anything. But doesn't the reading variable get reset every loop iteration, so reading equals in the inner if-condition in every iteration.

I don't understand the following Debounce code. (The complete code is at the bottom.) From what I understand, when the pin reads something, we wait at least 50 milliseconds before performing anything. But doesn't the reading variable get reset every loop iteration, so reading equals zero in the inner if-condition in every iteration.