#define ledPin 25
const int freq = 5000;
const int ledChannel = 0;
const int resolution = 8;  // 0-255

int ramp = 0;

void setup() {
  ledcSetup(ledChannel, freq, resolution);
  ledcAttachPin(ledPin, ledChannel);
  Serial.begin(115200);
}

void loop() {

  ledcWrite(ledChannel, ramp );  // analogWrite()
  ramp++;
  if(ramp>=256){
    ramp = 0;
  }
  Serial.print("0, 255, ");
  Serial.println(ramp);
  delay(15);
}