int i = 0;

void setup() {
  pinMode(9, OUTPUT);   // Set pin 9 as output
  Serial.begin(9600);   // Start the serial communication
}

void loop() {
  // Increase brightness
  for(i = 0; i <= 255; i += 5) {
    analogWrite(9, i);        // Set the brightness to 'i'
    Serial.println(i);        // Print the current value of 'i'
    delay(100);               // Wait for 100 ms
  }

  // Decrease brightness
  for(i = 255; i >= 0; i -= 5) {
    analogWrite(9, i);        // Set the brightness to 'i'
    Serial.println(i);        // Print the current value of 'i'
    delay(100);               // Wait for 100 ms
  }

  while(true){}  // Wait for 1 second before starting again
}