// Define the GPIO pins for the LEDs
const int ledPins[] = {18, 19, 21,22};

// Function to initialize the LED pins
void setup() {
  // Initialize serial communication
  Serial.begin(115200);

  // Set LED pins as OUTPUT
  for(int i = 0; i <4; i++) {
    pinMode(ledPins[i], OUTPUT);
  }
}

// Function to turn off all LEDs
void allOff() {
  for(int i = 0; i < 4; i++) {
    digitalWrite(ledPins[i], LOW);
  }
}

// Main function to control the LED blinking pattern
void loop() {
  // Pattern:----
  allOff();
  digitalWrite(ledPins[4], HIGH);
  delay(500); // 500 milliseconds

  // Pattern: ---*
  allOff();
  digitalWrite(ledPins[3], HIGH);
  delay(500);

  // Pattern: --*-
  allOff();
  digitalWrite(ledPins[2], HIGH);
  delay(500);

  // Pattern: -*--
  allOff();
  digitalWrite(ledPins[1], HIGH);
  delay(500);
 // Pattern: *---
  allOff();
  digitalWrite(ledPins[0], HIGH);
  delay(500);
}