WCH-Link-Nano

The cause of this project was that the speed of the previous DAP downloader had dropped a lot for unknown reasons, and it was bulky and used an extremely backward `micro-usb` interface, so I was looking for a new downloader everywhere.

However, none of the downloaders I saw on Taobao suited my taste. Finally, I bought a downloader from `muse lab`. The speed was indeed improved a lot, but the microcontroller it used was very hot and the user experience was not too good. good.

Later, I accidentally saw [What kind of paper do you bring for needle pricking](https://oshwhub.com/hgf_fgh) / [Super Mini WCH-Link Debugger](https://oshwhub.com/hgf_fgh/mini-wch -link-diao-shi-qi) project, this project reduces the size of the official `WCH-Link`, which makes me very surprised. So I made further modifications on the basis of this project, adapted it to the latest official firmware, and finally made such a downloader that is very satisfying to me
! [IMG_20230208_005936_edit_370962535451207.jpg] ! [Size comparison] Three downloaders are shown in the video The speed comparison shows that the latest `WCH-Link` firmware has improved the download speed a lot. I also tested an older version of the `WCH-Link` firmware (firmware that can switch between `RV` and `DAP` modes by pulling down the `tx` pin), and the speed was similar to the `original DAPLink` speed in the video.

The v1.2 circuit board in the project removes the buttons and leads the `D+` pin through a resistor and out of the pin header to replace the buttons and further reduce the size of the circuit board. But I don't like this kind of operation very much, so I just drew it without proofing and verification. If you are interested, you may be able to make a sample and test it.

The attachment includes firmware that can switch between `RV` and `DAP` modes by pulling down the `tx` pin. It is also an option. You can use `WCHISPTool` for firmware burning.
The latest version of firmware can be downloaded from [official website](https://www.wch.cn/downloads/WCH-LinkUtility_ZIP.html)