#define led 26

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  Serial.println("Hello, ESP32!");
  pinMode(led, OUTPUT);
}

void loop() {
  for(int i = 0;i<255;i++){
    analogWrite(led,i);
    delay(10);
  }
  for(int i = 255;i>=0;i--){
    analogWrite(led,i);
    delay(10);
  }
}