What if the serial port fails to open when the SCM uses stc-isp to download software?

Solution ：

1、 Right click “ This computer ” choice “ management ”

2、 Check to see if there is “ port （COM and LPT）”
a) If there is , And it can be downloaded before , Check whether the port for downloading software is selected correctly （ When inserting different USB There will be different port numbers when using the jack ）, If not , You can pull it out again and plug it in again USB Download line , Or restart the computer .

b) without “ port （COM and LPT）”, And you can't download it before , You can download a driver installer （CH341SER） solve , I am using USB The serial port program has been uploaded to the attention https://download.csdn.net/download/Boxjod/14683114 download

3、 If none of the above methods can solve , You can change a download line first , Check if it is Download line The problem of .（ Some download lines may be internally damaged , It can be powered on but cannot be used as a serial port cable ）