CH340T

The main function of the CH340 chip described in the given PDF is to act as a USB bus convert chip, enabling USB conversion to serial interface, USB conversion to IrDA infrared, or USB conversion to printer interface. It also supports common MODEM liaison signals in serial interface mode, allowing for the enhancement of asynchronous serial interfaces or direct connection of common serial devices to the USB bus. Additionally, when configured in infrared mode with an added infrared transceiver, the CH340 chip can function as a USB infrared adapter for SIR infrared communication.

According to the PDF, some of the features of the CH340 chip include: - Full speed USB device interface, conforming to USB Specification Version 2.0, requiring only external crystal and capacitance. - Emulation of standard serial interface, used for upgrading former peripheral devices or adding excess serial interfaces. - Ability to realize USB convert to serial interface, USB convert to IrDA infrared, or USB convert to printer interface. - In serial interface mode, it supplies common MODEM liaison signals for enlarging asynchronous serial interfaces of computers or upgrading common serial devices to USB bus directly. - In infrared mode, adding an infrared transceiver to CH340 can compose a USB infrared adapter to realize SIR infrared communication. The DataSheet of CH340 (the first).

To upgrade a common serial device to a USB bus directly using CH340, you can utilize its serial interface mode. CH340 provides common MODEM liaison signals in this mode, which can be used to expand the asynchronous serial interface of a computer or directly upgrade a common serial device to the USB bus. For more detailed information on upgrading to a USB printer interface, you can refer to the second manual CH340DS2.