// flunk any autorepeated tokens by timewindow
// like debounce:
// react to first and ignore any until T after last. repeated token

// here with gotten characters from a keypad said to be bouncing (almost certainly not, but hey!)

# include <Keypad.h>

# define BOUNCE 777  // exaggerated for testing

const unsigned char ROWS = 4;
const unsigned char COLS = 3;

char keys[ROWS][COLS] = {
  {'1', '2', '3'},
  {'4', '5', '6'},
  {'7', '8', '9'},
  {'*', '0', '#'}
};

//const unsigned char ROWS = sizeof ;
//const unsigned char COLS = 3;

unsigned char colPins[COLS] = {5, 4, 3};
unsigned char rowPins[ROWS] = {9, 8, 7, 6 };

Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);



void setup() {
  Serial.begin(115200);
  Serial.println("\nReject Repeat Delta\n");
}

char lastKey = NO_KEY;
unsigned long lastTime;

void loop() {
  unsigned long now = millis();

  char key = keypad.getKey();
  bool handled = false;;  // unless proven otherwise

// nothing 
  if (key == NO_KEY) handled = true;  // IR has no NO_KEY concept? check...

// this eats repeated too soon entries
  if (key == lastKey) {
    if (now - lastTime < BOUNCE) handled = true;
    lastTime = now;
  }

// here you have key the keystroke
  if (!handled) {
    lastKey = key;
    lastTime = now;

    Serial.println(key);
  }
}