Research On USB Device In Embedded System

Embedded system is a fast developing field. As a convenient storage device, USB flash disk is widely applied to the embedded system. At present, more and more embedded products have the function of USB interface. But what it actually refers to is the subordinate machine function. It can't identify the USB device on own initiative nor control or read/write it. Therefore, the realization of operating USB flash disk files in embedded system has the practical significance and the application prospect.USB flash disk is one kind of commonly used USB mass storage device. USB host is in the core position of USB topology structure. Any USB data transmission must be initiated and controlled by the host. Therefore, to carry on the file operation to USB flash disk in the embedded system, it is necessary to establish USB host system and file system in the embedded system. The embedded USB host system chooses Philips Corporation's LPC2210 chip as the CPU, ISP1161A1 chip as the host controller chip.First of all, the paper carries on the general development of embedded system and the principle of USB host, and analyzes the embedded real time systemμC/OS-II used in this design, also explained in detail the transplant process ofμC/OS-II on ARM microcontroller LPC2210. Then, the paper analyzes USB protocol and Mass Storage class protocol, realizes the USB driver and Mass Storage class protocol, designs the embedded USB host system, and the host system finishes the enumeration and the configuration function of USB device. Finally, the FAT32 file system is analyzed and suitably cut out, and the FAT file system which is more suitable to the embedded system is also designed, the interface between FAT file system andμC/OS-II is constructed, thus the USB flash disk's read- write operation on the embedded USB host is realized.According to the method mentioned in the paper, the USBhost system and FAT32 file system were constructed, the anticipated design purpose was realized.