之前很長一段時間起意，上傳程序到板子都沒有任何問題诺凡。
今天突然連不上了说贝，而我也確定串口連接選擇以及配置都沒有問題议惰。
重啟電腦是萬能法寶啊。
重啟了就恢復正常了狂丝。
猜測原因：昨天用python打開串口换淆。雖然python關(guān)掉了。但是也許一直占用著串口几颜。所以arduino沒法使用它的串口了倍试。
只是猜測，有空可以驗證一下蛋哭。
same day later....
Yes, it is the python who is using my COM3 so that my arduino cann't connect to the board. Remenber to use the common : ser.close() , to close the access to the port so that arduino IDE can use the port.
Reasonably, when I am using the arduino IDE to connect with the board over the COM3, my python cann't open the port. After I close the arduino IDE, the port can be connectted by python again.
