CH340 is a USB bus adapter chip, to achieve USB serial port or USB print port.

Special point:
> full speed USB device interface, compatible with USB V2.0.
> simulation standard serial port, used to upgrade the original serial port peripherals, or add additional serial port via USB.
> computer – side Windows operating system under the serial application is fully compatible, no modification.
> hardware full duplex serial port, built-in transceiver buffer, support communication baud rate of 50bps ~ 2Mbps.
> supports commonly used MODEM contact signal RTS, DTR, DCD, RI, DSR, CTS.
> provides RS232, RS485, RS422 and other interfaces through external level conversion device.
> CH340R chip supports IrDA specification SIR infrared communication, supports baud rate from 2400bps to 115200bps.
> supports 5V power supply voltage, 3.3v power supply voltage and even 3V power supply voltage.