#define LED_PIN 5  // Pin connected to the LED (change as needed)

int brightness = 0;      // Initial brightness level (0 to 255)
int fadeAmount = 10;      // Amount by which brightness will change per loop
unsigned long previousMillis = 0;  // Stores the last time we updated the brightness
const long interval = 300;  // Interval (in milliseconds) to change brightness

void setup() {
  // Set the LED pin as output
  pinMode(LED_PIN, OUTPUT);
}

void loop() {
  // Get the current time
  unsigned long currentMillis = millis();

  // Check if it's time to update the brightness
  if (currentMillis - previousMillis >= interval) {
    // Save the last time the brightness was updated
    previousMillis = currentMillis;

    // Adjust the brightness
    brightness = brightness + fadeAmount;

    // If brightness exceeds 255 or falls below 0, reverse the fade direction
    if (brightness <= 0 || brightness >= 255) {
      fadeAmount = -fadeAmount;  // Reverse the direction of brightness change
    }

    // Write the new brightness value to the LED (PWM control)
    analogWrite(LED_PIN, brightness);
  }
}