#include <Keypad.h>
#include <LiquidCrystal_I2C.h>
#include <TimerOne.h>


LiquidCrystal_I2C lcd(0x27, 20, 4);
const uint8_t ROWS = 4;
const uint8_t COLS = 3;
char keys[ROWS][COLS] = {
  { '1', '2', '3' },
  { '4', '5', '6' },
  { '7', '8', '9' },
  { '*', '0', '#'}
};

uint8_t colPins[COLS] = { 5, 4, 3, }; // Pins connected to C1, C2, C3, C4
uint8_t rowPins[ROWS] = { 9, 8, 7, 6 }; // Pins connected to R1, R2, R3, R4

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

int sec = 0;
unsigned long t1;
unsigned long period;
bool _update = false;

void setup() {
  Serial.begin(9600);
  lcd.init();
  lcd.backlight();
  Timer1.initialize(1000000);
  Timer1.attachInterrupt(abc);
}

void loop() {
  int t1 = millis();

  char key = keypad.getKey();

  if (key != NO_KEY) {
    //Serial.println(key);
    lcd.setCursor(0, 0);
    lcd.print(key);
  }
  //Serial.println(millis() - t1);
  /* if (sec < 59)
     sec++;
    else
     sec = 0;
    lcd.setCursor(0, 2);
    lcd.print(sec);
    lcd.print(" ");
    delay(1);*/
  if (_update) {
    lcd.setCursor(0, 2);
    lcd.print(sec);
    lcd.print(" ");
    _update = false;
  }
  
}
void abc() {
    if (sec < 59)
      sec++;
    else
      sec = 0;
    _update = true;
  }