/**
 * Fades an LED on and off using analogWrite().
 *
 * On ESP32 Arduino core v3.x, analogWrite() is a convenience wrapper
 * around the LEDC library. It defaults to 1 kHz PWM at 8-bit resolution.
 * This is the simplest way to fade an LED—identical to Arduino Uno code!
 *
 * See: https://makeabilitylab.github.io/physcomp/esp32/led-fade
 */

const int LED_OUTPUT_PIN = 13;  // GPIO 13
const int DELAY_MS = 8;         // Small delay between steps for a smooth fade

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

void loop() {
  // Fade up: ramp from 0 (off) to 255 (full brightness)
  for (int brightness = 0; brightness <= 255; brightness++) {
    analogWrite(LED_OUTPUT_PIN, brightness);
    delay(DELAY_MS);
  }

  // Fade down: ramp from 255 back to 0
  for (int brightness = 255; brightness >= 0; brightness--) {
    analogWrite(LED_OUTPUT_PIN, brightness);
    delay(DELAY_MS);
  }
}