void wifi_ap() {
  Serial.begin(19200);
  WiFi.mode(WIFI_AP);
  IPAddress local_IP(192, 168, 7, 2);
  IPAddress gateway(192, 168, 7, 1);
  IPAddress subnet(255, 255, 255, 0);
  WiFi.softAPConfig(local_IP, gateway, subnet) ;

  //启动AP模式，并设置账号和密码
  boolean result = WiFi.softAP("mydoor1", "277791907");
  if (result) {
    //输出 soft-ap ip地址
    Serial.println("AP->ok");
  } else {
    Serial.println("AP->erorr");
  }
}