#define PWM_PIN     5       // GPIO pin for PWM
#define PWM_FREQ    5000    // PWM frequency (Hz)
#define PWM_CHANNEL 0       // PWM channel
#define PWM_RES     8       // PWM resolution (8 bits: 0-255)

void setup() {
  ledcSetup(PWM_CHANNEL, PWM_FREQ, PWM_RES);   // Configure PWM channel
  ledcAttachPin(PWM_PIN, PWM_CHANNEL);         // Attach pin to channel
}

void loop() {
  // Example: gradually increase and decrease speed/brightness
  for (int duty = 0; duty <= 255; duty++) {
    ledcWrite(PWM_CHANNEL, duty); // Set duty cycle (0-255)
    delay(10);
  }
  for (int duty = 255; duty >= 0; duty--) {
    ledcWrite(PWM_CHANNEL, duty);
    delay(10);
  }
}