CMSIS-DAP compatible debugger [Vllink Lite]

According to my previous tests, the continuous read and write speeds of ST-Link V2 and Jlink V8 are around 160KB/S. However, most CMSIS-DAP debuggers are limited to full-speed HID and the speed is difficult to increase. The continuous read and write speed of DAPLINK+ OpenOCD The speed is only 23KB/S.
      At the beginning of the year, I tried to use NUC505 for CMSIS-DAP. 505 should be the cheapest integrated USB HS PHY microcontroller on the market. The high-speed HID message can be set to 1024Byte, and the sending and receiving interval is 125uS. There is no bottleneck in the USB part. However, its SPI module is very slow. After a transmission is completed, it will wait for several CLKs before triggering the completion flag. Even if the CLK is increased to 14MHz, the continuous read and write speed is only 150KB/S, which can only be said to be dead wood. It cannot be carved.
      The protagonist this time, GD32F350, I knew about it last year. I heard that it is the same price as GD32F150. The USB part has been changed to DWCOTG, and the execution speed of the last 32KB code will not be snail. After reading the datasheet in detail, I found that the internal 48M clock can be calibrated through the USB SOF signal, so that a crystal oscillator is not needed. The price is said to be as low as 30 cents in bulk. Well, it’s just so-so. Anyway, I bought 3pcs on Taobao for a total of 21 yuan. In general, it "seems" to be a super low-price solution, similar to the SPI design of the ST-LinkV2 main chip, and may be able to reach the mainstream speed indicator of 160KB/S, so it is worth a try.