const int ledPins[] = {12, 13, 14, 15};  // LED pins
int counter = 15;                        // Start count at 15

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

void loop() {
  // Display the counter value on the LEDs
  displayCounter(counter);

  // Decrement the counter
  counter--;

  // Reset counter to 15 if it goes below 0
  if (counter < 0) {
    counter = 15;
  }

  delay(1000);  // Wait for 1 second
}

void displayCounter(int count) {
  for (int i = 0; i < 4; i++) 
  {
    int bit = (count >> i) & 0x01;  // Get the i-th bit of the count
    digitalWrite(ledPins[i], bit);  // Set the LED state
  }
}