The problem is as follows:
Follow the normal steps to use KEIL5 to Rongchu stm32 download program, swd download method prompts no cortex-m SW device Found,jtag way hint no cortex-m device found in Jtag chain
Reason:
The Jtag interface arrangement of Rongchu STM32 MCU is not standard JTAG cabling method
Workaround:
Wiring yourself in JTAG or SWD's wiring mode
10 feet of the Itag interface, 3, 4 feet (Trst corresponds to Stm32 PB4), 5th foot (TDI corresponds to Stm32 PA15), 6th foot (Tdo\swo corresponds to Stm32 of PB3), 7th foot (Tms/swdio corresponds to Stm32 of PA13), 9th foot (TCK/SWCLK corresponds to Stm32 's PA14).
The SW mode only needs to be answered: Jlink's 1th foot (VDD), 7th foot (Tms/swdio corresponds to Stm32 PA13), 9th foot (tck/swclk corresponding stm32 of PA14), Any foot in the 4.6.8.10.12.14.16.18.20 (feet), need to be described is the 15th foot (reset corresponding to Stm32 Nrst) can be connected, everyone according to the actual decision (for the sake of insurance or recommended).
Reference: http://blog.sina.com.cn/s/blog_981380d00102uyrv.html
Rongchu STM32 Single-chip microcomputer with J-link download unrecognized solution