Remote Access System Design Of USB Storage Device

In this thesis, a scheme of accessing USB storage device in embedded system through the method of remote access has been put forward, which is based on currently popular network disk storage.System design is implemented on FPGA platform, including a USB2.0interface, which can be used to connect peripheral USB high-speed or full-speed devices, and a standard RJ45network interface. Design goal is any PC within the LAN that runs Linux operating system and is installed with NFS client as well as possesses operation authority. USB storage files of this PC can be accessed, read and written through Ethernet. Client server of access system works as NFS client that accesses files and directory of storage device through RPC process in NFS protocol clearly and unlimitedly. The whole system achieves the functions of NFS SERVER, and the work of this essay involves hardware layer, system layer and software layer.Xilinx Virtex-5Board is adopted as system hardware platform, with MicroBlaze processor soft core installed inside as central processing unit.32-bit RISC (Reduced instruction set computer) optimized structure was put into use in MicroBlaze, which is a very simplified and high-performance soft core occupying few on-chip resources. On the basis of a deep understanding of USB2.0protocol, IP core of USB host controller (USB_HOSTCTL) has been designed under Xilinx ISE development tool with VHDL, waveform simulation and verification of each module done. After creating a new hardware project with Xilinx development tool EDK, add the USB_HOSTCTL designed to it in the way of register access, generating net list, bit torrent file and library and board support package needed in software.An embedded operating system PetaLinux suitable for transplant on FPGA platform has been adopted in this system. Then hardware platform created in Xilinx EDK is added to source code tree directory of PetaLinux, eventually completing operating system transplantation. The migration of NFS application program enables the system to execute functions of NFS server, after which system image file is written to FLASH chip. Program is booted to run automatically after power up, booting Linux kernel which is finally loaded into SDRAM for running. Meanwhile, elaborate analysis of NFS server operating principles has been done, so has the description of NFS server levels and key processes.