Checking for short vs long press with debounce

Question

I'm a complete beginner with Arduino but have done quite a bit of searching and can't seem to fix this problem.

I'm trying to create a procedure that is repeatedly called in the main loop() that will set a variable depending on the current state of a button, as well as the duration the button has been or was pushed for. This code is probably messier than it needs to be, but it just seems to leave the variable at 0. What am I missing?

There is code in the loop() itself that sets the rotaryButtonToAction variable back to noPress once it has been acted upon.

#define noPress 0
#define shortPressReleased 1
#define longPressReleased 2
#define shortPressHolding 3
#define longPressHolding 4

int rotaryButtonState;
int rotaryButtonReading;
int lastRotaryButtonReading = HIGH;
int timeOfLastRotaryButtonReadingChange = 0;
int debounceDelay = 50;
int longPressDelay = 300;
int rotaryButtonToAction = 0;

void checkRotaryButton() {
  if (rotaryButtonToAction == noPress) { // if there is nothing to action, check the state of the button
    rotaryButtonReading = digitalRead(ROTARY_BUTTON); // store pin's current state
    if (rotaryButtonReading != lastRotaryButtonReading) { // if pin state has changed from the last reading, set timeOfLastRotaryButtonReadingChange to the time of the change
      timeOfLastRotaryButtonReadingChange = millis();
    }
    if (millis() - timeOfLastRotaryButtonReadingChange > debounceDelay) { // if more time has passed than the debounce delay, change the action state of the button
      if (rotaryButtonReading = LOW) { // if the button is still pressed, set the action to indicate it has been pressed and is still pressed
        rotaryButtonToAction = shortPressHolding;
      }
    else { // if the button was pressed for longer than the debounce delay and was released, set the action
      rotaryButtonToAction = shortPressReleased;
      }
    }
  } 

  if (millis() - timeOfLastRotaryButtonReadingChange > longPressDelay) { // if more time has passed than the long press delay, change the action state of the button
    if (rotaryButtonReading == LOW) { // if the button is still pressed, set the action to indicate it has been pressed and is still pressed
      rotaryButtonToAction = longPressHolding;
    }
    else { // if the button was pressed for longer than the long press delay and was released, set the action
      rotaryButtonToAction = longPressReleased;
    }
  }

} // end checkRotaryButton

Answer 1

Never used Arduino, but don't you need to use double equal signs in a compare function?

So, if (rotaryButtonToAction = noPress) should be if (rotaryButtonToAction == noPress) instead?

Answer 2

Well, after much playing around I've taken a completely different approach that seems to do just what I need. I believe this is an example of a "state machine", though I'm new to all of this...

void checkRotaryButton() {
  rotaryButtonReading = digitalRead(ROTARY_BUTTON); // store pin's current state
  if (rotaryButtonReading != lastRotaryButtonReading) { // if pin state has changed from the last reading
    timeOfLastRotaryButtonChange = millis(); // if pin state different, store the time of the state change
  }
  timeSinceLastRotaryButtonChange = millis() - timeOfLastRotaryButtonChange;

  if (rotaryButtonReading == LOW && timeSinceLastRotaryButtonChange < debounceDelay) {
    // has only been low for less than the debounce time - do nothing
  }
  if (rotaryButtonReading == LOW && timeSinceLastRotaryButtonChange > longPressDelay && rotaryButtonToAction != longPressed) {
      rotaryButtonToAction = longPressed;
      Serial.println("button pressed long");  
  }
  if (rotaryButtonReading == LOW && timeSinceLastRotaryButtonChange > debounceDelay && timeSinceLastRotaryButtonChange < longPressDelay && rotaryButtonToAction != holdingPress) {
      rotaryButtonToAction = holdingPress;
      Serial.println("holding button pressed");  
  }
  if (rotaryButtonReading == HIGH && timeSinceLastRotaryButtonChange > debounceDelay && rotaryButtonToAction == holdingPress) {
      rotaryButtonToAction = shortPressed;
      Serial.println("released short press");    
  }


  lastRotaryButtonReading = rotaryButtonReading; // store this reading for comparison the next time the procedure loops
} // end checkRotaryButton