Jlink V9 DIY High Speed ​​SWD

The Jlink OB made by F072 has a maximum speed of 3000kHz, and the Jlink V9 has a maximum speed of 12000kHz. The hardware uses STM32F205RET6, and the firmware size is 256KB, but in fact the bootloader accounts for 40, and the actual APP accounts for 196, so you can use RCT6, and the maximum baud rate of the serial port is only It supports up to 230400, so the serial port is not as easy to use as OB.

When DFU downloads firmware, you need to short BOOT0 to 3.3V and short the RX pin to GND to enter DFU mode.
You can also use the SWD interface to directly download the bootloader and open jlink commander to automatically upgrade the firmware.
If there is no license, open jlink. Commander, enter the following sn. Enter whichever version you like.
Exec SetSN=20281318 V9.2
Exec SetSN=20381318 V9.3
Exec SetSN=20481318 V9.4
Exec SetSN=20581318 V9.5
Exec SetSN=20681318 V9.6
Exec SetSN= 20781318
The new version of Jlink driver in V9.7 needs to add more content, such as
exec SetSN=20781318,0xCF2EF286