const int ledPin = 16;
const int freq = 5000;
const int ledChannel = 0;
const int resolution = 8;

void setup(){

  ledcSetup(ledChannel, freq, resolution);

  ledcAttachPin(ledPin,ledChannel);
}

void loop(){
for(int dutyCycle = 0 ; dutyCycle <= 255; dutyCycle++){
ledcWrite(ledChannel, dutyCycle);
delay(15);
}
for (int dutyCycle = 255 ; dutyCycle >= 0; dutyCycle--){
  ledcWrite(ledChannel, dutyCycle);
  delay(15);
}

}