/**
 * ESP32 Fade example
 *
 * See: https://makeabilitylab.github.io/physcomp/esp32/led-fade
 */

const int LED_OUTPUT_PIN = 13;  // GPIO 13
const int PWM_FREQ = 5000;      // 5 kHz — fast enough to avoid visible flicker
const int PWM_RESOLUTION = 8;   // 8-bit resolution: duty cycle ranges from 0 to 255
const int MAX_DUTY_CYCLE = (1 << PWM_RESOLUTION) - 1;  // 2^8 - 1 = 255

const int DELAY_MS = 6;         // Small delay between steps for a smooth fade

void setup() {
  Serial.begin(115200);

  // Attach a PWM channel to the pin with the specified frequency and resolution.
  // The library automatically assigns an available hardware channel.
  ledcAttach(LED_OUTPUT_PIN, PWM_FREQ, PWM_RESOLUTION);
}

void loop() {
  // Fade up: ramp duty cycle from 0% (off) to 100% (full brightness)
  for (int dutyCycle = 0; dutyCycle <= MAX_DUTY_CYCLE; dutyCycle++) {
    ledcWrite(LED_OUTPUT_PIN, dutyCycle);
    Serial.print("Duty cycle: ");
    Serial.println(dutyCycle);
    delay(DELAY_MS);
  }

  // Fade down: ramp duty cycle from 100% back to 0% (off)
  for (int dutyCycle = MAX_DUTY_CYCLE; dutyCycle >= 0; dutyCycle--) {
    ledcWrite(LED_OUTPUT_PIN, dutyCycle);
    Serial.print("Duty cycle: ");
    Serial.println(dutyCycle);
    delay(DELAY_MS);
  }
}