// Two Digit Count Down Timer
#include <SevSeg.h>

SevSeg sevseg;

#define degit1 2
#define degit2 3

unsigned long previousMillis = 0;
const long interval = 1000; // 1 second
int countdownSeconds = 20;

void setup() {
  // put your setup code here, to run once:
  byte numDigits = 2;
  byte digitPins[] = {degit1, degit2};
  byte hardwareConfig = COMMON_CATHODE;
  byte segmentPins[] = {4, 5, 6, 7, 8, 9,10};
  bool resistorsOnSegments = true;

  sevseg.begin(numDigits, digitPins, hardwareConfig, segmentPins, resistorsOnSegments);

  sevseg.setBrightness(90);

}

void loop() {
  // put your main code here, to run repeatedly:
  unsigned long currentMillis = millis();

  // check if 1s is passed
  if (currentMillis - previousMillis >= interval) {

    // update time method
    updateTimer();
    // save current time for iteration
    previousMillis = currentMillis;
  }
  
  // Display the Numbers
  sevseg.setNumber(countdownSeconds, 0);
  sevseg.refreshDisplay();
}

void updateTimer() {
  // decrement 
  countdownSeconds--;

  // check if the countdown reach zero
  if(countdownSeconds < 0 ) {

    // reset the countdown
    countdownSeconds = 20;
  }
}