STM32F103C8T6 minimum system + DAP-Link

When learning STM32, many users encounter minor issues such as numerous wiring connections, difficult debugging, and cumbersome programming. I learned from the LCSC open-source platform that the CH549G can be programmed with firmware to become a DAP-Link, possessing normal SW download functionality and a virtual serial port that connects to the STM32F103C8T6's serial port 1, allowing direct downloads from Keil for easier debugging. (Link: https://oshwhub.com/hhh89/wch-link-v2).

However, this isn't enough. During development, situations often arise where other chips need to be programmed. Guided by the principle of doing things to the best of one's ability, I cleverly used an analog switch CH440R to bring out the programmer's SW and serial ports, enabling it to program other chips. It also incorporates a reverse current protection design, and the pin count and arrangement are compatible with commonly used minimum system boards. A DIP switch can control whether programming is for the C8T6 or an external chip.

To facilitate observation of program operation, a standard PC13 LED is typically connected. Here, a smaller WS2812 BrGB LED (2020 package) is chosen instead, which can display different operating states of the microcontroller and is more helpful for development and debugging
. [4c0405fbe8d03de8efde5e07c99358f.jpg] The silkscreen on the back explains the function of the DIP switches.

Note: The high-speed external crystal oscillator used is 12MHz.
When soldering, prioritize removing any solder bridging to the Type-C port.