USB connector is an external bus standard, used to regulate the connection and communication between computers and external devices, USB interface plug and play and hot swap functions. The USB interface can connect 127 kinds of peripherals, such as mouse and keyboard. USB is in the end of 1994 by Intel and other companies jointly launched in 1996, has successfully replaced the serial port and parallel port, has become today's computer and a large number of electronic intelligent devices must be equipped with the interface.

USB version has experienced years of development, for most engineers, the development of USB2.0 interface products the main obstacles are: to face the complex USB2.0 protocol, write their own USB device drivers, familiar with the programming of the single chip computer. This not only requires considerable VC programming experience, but also the ability to write USB interface hardware (firmware) programs, so most people give up their own development of USB products. In order to simplify the complex problem, some connector manufacturers specially designed the USB2.0 protocol conversion module. USB20D module can be seen as a USB2.0 protocol converter, the computer's USB2.0 interface into a transparent parallel bus, just like the MCU bus, so that the design of USB2.0 products can be completed in a few days.