// Define the LED pins
const int ledPins[] = {23,22,17,4}; // Pins connected to LEDs
int counter = 15; // Start counter at 15 (maximum for 4-bit)

void setup() {
  // Initialize the LED pins as outputs
  for (int i = 0; i < 4; i++) {
    pinMode(ledPins[i], OUTPUT);
  }
}

void loop() {
  // Display the current counter value on the LEDs
  for (int i = 0; i < 4; i++) {
    digitalWrite(ledPins[i], (counter >> i) & 0x01);
  }

  // Decrement the counter
  counter--;
  
  // Reset counter after it reaches -1 (0 to 15 for 4-bit counter)
  if (counter < 0) {
    counter = 15;
  }

  // Wait for one second
  delay(1000);
}