Dap-link for USB C port

Original engineering design source: https://oshwhub.com/yacter/stm32-daplink
was changed to USB-C while reducing the size and simplifying some circuits.

## First burn the bootloader
- use STM32 ST-LINK Utility or STM32CubeProgrammer to burn "stm32f103xb_bl_crc.hex" in the firmware

   STM32 ST-LINK Utility download link https://www.st.com/zh/development-tools/stsw-link004.html#get-software
   STM32CubeProgrammer over 50m download link https://www.st.com/zh/development -tools/stm32cubeprog.html#get-software

2020-0520 Update: The CH340 eight-pin module lacks the 104 capacitor grounding and cannot work properly. The V3 version is solved through flying wires. It is not added because the welding position is convenient and can be solved directly with 0805 packaging.

                            The DAP-LINK module circuit has all passed. It is the first time to reinstall the driver. I don’t know the reason. Reinstalling the driver solves the problem. RST lacks a pull-up resistor and uses 0805 flying wire. The computer cannot recognize the lack of resistor. Adding a resistor cannot burn the firmware. , the solution is not to solder first, use tweezers to short-circuit and plug in to verify, and finally add the resistor. See comparison chart for welding methods                        

                          V4 adds st-link firmware, which only supports link but no serial port function. It needs to be replaced with a large-capacity chip.

Comparison chart: The above is the old version. The new version has reduced part of the size.

## Determine the target board model. Here we take f103 as an example
- press the button on DAPLINK, and then plug in the USB until a name named

MAINTENANCE USB flash drive.
- Then copy "stm32f103xb_stm32f103rb_if.hex" to the USB flash drive.

Remember to add the pull-up resistor of OUT-RST

- Then re-plug the USB and it can be used normally.
## If you need to install the driver, please see below.

If there is no driver installed and the following operation is performed, no exclamation mark will be ignored.

   Update Driver---Browse My Computer for Driver---Select from the list of available drivers on My Computer as shown below