Ultra-small DAP-Link debugger based on CH552G

Referring to
most of the code and hardware design from https://github.com/abgelehnt/Tiny-DAPLink, I modified the PCB according to the single-sided layout, and fine-tuned the parts of the software code that did not match the schematic, and finally formed the firmware.
The link to the Liangshan School debugger is https://oshwhub.com/lengyuefeng/a7c57e6d86bd47789178df3fda9219dc. I searched oshwhub and couldn’t find it. Finally, I found out that it was because the project naming was a bit subtle.
 
Preface
: When I was in the laboratory before, I found that my teammate had an ultra-small debugger with DAP Link written on it (the aforementioned Liangshan School debugger). The core was CH552G. Because I couldn't find any information at the time, I came up with my own idea. The idea of ​​making one.
 
Features:
The entire board components adopt a single-sided layout. For newly purchased chips, since it automatically enters the IAP programming program after power-on, the 1K resistor on the back (used to enter programming mode) does not need to be attached.
The volume is made as compact as possible without using adapters. Although using the adapter can make the board body smaller, the actual volume occupied by the debugger plus the leads may not necessarily be reduced.
The debugging port is led out with a 2.54 pin header and can be directly connected with DuPont wire.
This debugger needs to be used with OpenOCD, but I am not responsible for training in the use of OpenOCD. CoFlash does not recognize this debugger.
Note: SWDIO/SWWDK has been converted to 3.3V level using 74LVC1T45, but the serial port and USR pin are both 5V level. CH552G cannot run at full speed of 24MHz when powered by 3.3V.
 
Finally, attach a comparison picture with the previous CMSIS-DAP of CH32F103C8T6.