const int LED_PIN = 9;
void setup() {
pinMode(LED_PIN, OUTPUT);
}
void loop() {
for (int brightness = 0; brightness < 256; ++brightness) {
analogWrite(LED_PIN, brightness);
delay(10);
}
for (int brightness = 255;brightness >= 0; --brightness) {
analogWrite(LED_PIN, brightness);
delay(10);
}
}