CH341 is a USB bus convert chip, providing UART, printer port, parallel and synchronous serial with 2-wire or 4-wire through USB bus. In UART mode, CH341 provides alternant rate control signals such as serial transfer enable, serial receive in ready etc. It also supplies common MODEM communication signal in order to expand UART for computer or upgrade common synchronous interface device to USB bus directly. In printer port mode, CH341 supplies standard USB printer port which compounds USB relevant protocol and Windows operate system used to upgrade ordinary parallel printer to USB bus directly. In parallel mode, CH341 gives out 8-bit parallel in EPP or MEM mode. It can be used to input/output data directly without MCU/DSP. Besides, CH341A also supports some common synchronous serial such as 2-wire (SCL, SDA) and 4-wire (CS, SCK/CLK, MISO/SDI/DIN and MOSI/SDO/DOUT) interface.