USB Interface Design In Embedded System

Along with the gradually extension of the applied field of USB, people hope that the USB can be applied in various computer field, particularly in the ambulation data exchange field without PC. USB Host is the core in the USB topology structure, any data delivers must be started and controlled by the host. Therefore, some problems enter the USB developer's discussion agenda, for example "how to apply USB to embedded field? How communicate from dot to dot". Just about this kind of new requirement, the embedded application of the USB Host becomes the focus of this realm, relative to USB device development in embedded system.The purpose of this paper is to develop the USB host and slave interface in ARM development platform. The main work is to write drivers. In drivers writing, there are two parts host driver software package and devices driver software package. The author mainly writes the host controller driver (HCD) in the host driver's package. It is the abstract of the host controller. It provides the control function and interface function with USB driver (USBD). Then the author writes the top layer's device class drivers. It is the finally alternant module with application program, accomplishing the particular USB devices' visiting and providing the accessing interface for the application program. Linux supports various devices class driver. In this paper is to carry out MASS STORAGE class driver. Device software package include the following drivers. Device controller driver: it mainly completes the total data deliver on bus; Protocol layer driver: it is mainly to carry out the standard USB claim protocol.With the embedded system demand for the USB host function becomes more and more, embedded host must extend the supporting device type gradually. USB Hub should even be supported by the embedded USB host because it is an indispensable device for USB system. The importance of the USB Hub relates to its position in USB topology structure. Hub is the relay station of the USB system and gate of all USB devices connect to USB system because it connects the host and device. In this paper, it carried out the supporting to the hub. Through the Hub can access the USB devices.