USB to TTL_CH330N solution verification board

This project is a solution verification version for [Lichuang Mall](https://www.szlcsc.com/)CH330N ([Product No.: C108996](https://item.szlcsc.com/110217.html)) design. This project is a sample project of [EDA Open Source Hardware Platform](https://oshwhub.com/) [Solicitation Order for Solution Verification Module](https://oshwhub.com/rewards/f4bbab6365034e80aadb8f8ebf77c846). This verification board supports automatic downloading of STC microcontroller. CH330 is a USB to serial port chip, used to expand asynchronous serial ports for computers, or upgrade ordinary serial port devices to USB bus. ●CH330N has simple peripheral components; ●Built-in crystal oscillator; ●Simulated standard serial port, used to upgrade original serial port peripherals, or add additional serial ports through USB. ● The serial port application under the Windows operating system on the computer side is fully compatible and does not need to be modified. ● Hardware full-duplex serial port, built-in independent transceiver buffer, supports communication baud rate of 50bps~2Mbps. ● Supports 5, 6, 7 or 8 data bits, supports odd parity/even parity/flag parity/blank parity. ● Provide RS232, RS485 and other interfaces through external level conversion devices. ● Supports 5V power supply voltage and 3.3V power supply voltage.