const int ledPin = 12;
void setup() {
Serial.begin(115200);
pinMode(ledPin, OUTPUT);
}
  void loop() {
  for (int brightness = 0; brightness <= 255; brightness++) {
  analogWrite(ledPin, brightness);
  Serial.println(brightness);
  delay(10);
  }
    for (int brightness = 255; brightness >= 0; brightness--) {
    analogWrite(ledPin, brightness);
    Serial.println(brightness);
    delay(10);
  }
}