已经更新固件。WIFI连接成功。使用教程里的《物联网应用（上）》课程，
根据实际更改了产品ID,设备ID和APIkey，并确认它们是正确的。但是在oneNET官网上掌控板始终离线状态。
报错信息如下：
Traceback (most recent call last):
File "main.py", line 82, in <module>
File "main.py", line 44, in OneNET_set
up
File "umqtt/simple.py", line 99, in co
nnect
MQTTException: 4
eagler8
2020年06月02日
昨天实验中，发生过一模一样的情况，串口输出是——
Traceback (most recent call last):
File "main.py", line 54, in <module>
File "main.py", line 38, in OneNET_setup
File "umqtt/simple.py", line 99, in connect
MQTTException: 4
MicroPython v2.0.1-18-gbe8fbdd-dirty on 2020-04-24; mpython with ESP32
多次尝试，后来搞好了，见
MicroPython动手做（26）——物联网之OneNET
https://www.labplus.cn/posts/5ed45c28d5b5b21f68513963