Design & Implementation Of Reusable Software For USB Host Driver In Embedded Systems

USB is a technology of Universal Serial Bus which is'master/slave'(host/peripheral) constructive, It has many advantages, such as simplicity, high bandwidth, high reliability, easily scalable, hot-plug and so on. The traditional USB hosts are mainly used for PCs. Currently, with the rapid development of consuming electronic products, USB host contoller has been applied in more and more embedded products. Under this situation, a USB host system should be realized in the embedded system.Traditional development of USB driver is for the USB peripheral. The host driver is mainly provided by the operating system. In the development of USB host, for the two operating systems based on desktop, Windows doesn't open the source code while porting from Linux is not easy. However, in the embedded operating system, such asμCOS, VxWorks, QNX and so on, the USB host software stack is also not open either. Therefore, for the chip designer or the system solution producer, to realize a set of USB host driver which can be widely used and easily ported is more meaningful. Besides, in most embedded system software by self-development, there is usually an unclear borderline among low level driver, operation system and application. This increases the software coupling. Once there are some changes in hardware or operating system, the cost and the risk will increase and the reusability is greatly reduced.Under this background, according to the character of embedded system, and by reducing and porting from Linux source code, this paper designs a set of embedded USB host driver which has high reusability and can be used universally.First, this paper studies the structure of hardware and software in USB host system, then analyses the Linux USB host driver, and estimates the difficulty of porting it from Linux. Second, based on the reuse methodology, it designs embedded software architecture for USB host driver. Third, it port USB host dirver from Linux by reducing the core data structure and reforming corresponding cource code.Eventually, the paper realizes the support of USB mass storage device by applying the target USB host driver to a typical embedded system: Set-Top-Box, and gives the verification and testing for resuability, function and performance.