void setup() {
  // put your setup code here, to run once:
  pinMode(13, OUTPUT);

  // 串口 设置波特率    1 <=> 1
  Serial.begin(115200);

  
}

void loop() {
  Serial.println(millis());



  int attenVal = analogRead(A0);    // [0,1023]
  // Serial.println(attenVal);

  int ledLight = map(attenVal,0,1023,36,255);
  // 38
  analogWrite(13, ledLight);   // [37,255]  =>   [0%，100%]
}