Check the clock frequency & that the baud rate required can be achieved. Error of <1 is never a problem, <2 will work but is undesirable, 5 will not work. Note that this assumes that the other end of the link has perfect timing, which will norm

STM32的JTAG / SWD接口是通过20PIN连接线连接目标板，所以ST-LINK/V2连接至STM32目标板时需要注意连接方向(The JTAG / SWD interface of STM32 connects the target board through the 20PIN connection line, so the connection direction needs to be noticed when ST-LINK/V2 is connected to the STM

DAP-LINK工具STM32源码，支持STM32F103作为控制器(DAP-LINK Tool STM32 Source Code)