First of all, your PC should have upper computer software. If debugging, you can find a serial assistant on the Internet, and then configure the communication protocol (start bit, stop bit, data bit, etc. ). The lower computer, that is, your Zhou Ligong microcontroller, should also configure the communication protocol, such as baud rate, according to the serial port mode you choose.

After they are all configured, they can be debugged, sent by PC and received by MCU. Single-chip microcomputer can send and PC can receive.

In addition, pay special attention to electrical isolation, isolation, isolation, and say the key things three times.

If the power supply of your single-chip microcomputer has been isolated, it is simple, otherwise you should use isolated data lines to communicate between the upper computer and the lower computer.

Good luck.