Ultra-small usb to uart (ttl)

This project is used to verify the solution verification board design of Lichuang Mall microcontroller CH340E. At the same time, this project refers to part of the circuit board design of @wangx 's USB indicator light. I am very grateful to wangx for the open source USB indicator light design. This design contains the necessary peripheral circuits required for the operation of CH340E, and all its pins are lead out for future use. This design also contains a three-color LED light from Guoxing Optoelectronics, of which blue is used to indicate the power status, and red and green indicate RX respectively. and TX (PS: red with green?) as shown in the figure. The PCB consists of three parts, which are used to assemble the upper, middle and lower three-layer boards of the finished product. Three 0.8mm thick PCBs are opened through the top copper foil layer and the tail. Pin header connection, so that it can be plugged into the USB interface normally to realize its function