Countdown Timer
Arduino output
TEHILLAH MULOMBA

#include <LiquidCrystal.h>
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

//Sets the duration for the countdown
long hour = 0, minute = 0, second = 10;

long countdown_time = (hour*3600) + (minute * 60) + second;

//LED Pin
int LED = 10;

void setup() {
  pinMode(LED, OUTPUT);
  lcd.begin(16, 2);
  lcd.setCursor(2, 1);
  lcd.print("HH:MM:SS");
}

void loop() {
  lcd.setCursor(0, 1);
 //Calculates the time to be displayed
  long countdowntime_seconds = countdown_time - (millis() / 1000);
  if (countdowntime_seconds >= 0) {
    lcd.print("T-");
    long countdown_hour = countdowntime_seconds / 3600;
    long countdown_minute = ((countdowntime_seconds / 60)%60);
    long countdown_sec = countdowntime_seconds % 60;
    lcd.setCursor(2, 1);
    //Displays 0 if set duration elapsed
    if (countdown_hour < 10) {
      lcd.print("0");
    }
    lcd.print(countdown_hour);
    lcd.print(":");
    if (countdown_minute < 10) {
      lcd.print("0");
    }
    lcd.print(countdown_minute);
    lcd.print(":");
    if (countdown_sec < 10) {
      lcd.print("0");
    }
    lcd.print(countdown_sec);
    lcd.print("s");
    if (countdowntime_seconds == 0) {
      digitalWrite(LED, HIGH);
    }
    if (countdowntime_seconds > 0) {
    lcd.setCursor(0, 0);
    lcd.print("Deadline In:");
    }

//Displays text once duration elapsed.
    else {
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("Submission");
      lcd.setCursor(0, 1);
      lcd.print("Closed!!");
    }
  }
  delay(500);
}