Research And Design Of Virtual Serial Port Based On USB Communication Device Class

USB interface supports plug and play which has unified standards, so it has awide range of applications. More and more computer device use USB interface totransfer data, so how to make many old deives to support USB interface withoutchanging current application is becoming the hot field.USB Communication Device Class and it’s abstract control model are studied,principles of Communication Device Class and implementation techniques of abstractdevice are also anlyzed in the thesis. On the basis of this, design and implementation ofvirtual serial port driver based on Communication Device Class are given.The overall structure and implementation scheme of virtual serial port driver basedon CDC are designed. The virtual serial port driver is made up of two parts which arecommunication command transfer module and data transmission module. Thecommunication command transfer module satisfies the specification of abstract controlmodel, and the data transfer part improves the technique of current virtual serial port.The main works in the thesis are as follows:(1) The request and transfer model for USBprotocol are studied, and the implementation techniques of virtual serial port areanlyzed.(2) The implementation scheme of virutal serial port driver that satisfy abstractcontrol mode in CDC is gaven. A new template for the development of virtual serialport based on CDC is brought out, and it describes some issues for the virtual serial portdriver in detials, at the same time, the processing steps for virtual serial port driver isimproved.(3) The improved data processing steps for virtual serial port driver isapplied in the implementation of vitual serial port driver, and a stable, high-speed virtualserial port is made. At last, the test for the virtual serial port driver on ActiveSync isgaven, and the test result show that it’s function is chieved the requirement goals.