USB Mass Storage类设备的设计与实现

针对嵌入式系统与PC主机大量数据传输的需要，使用SD卡做为存储介质设计实现USB Mass Storage类设备。主机和存储设备之间的通讯严格按照USB20协议和USB Mass Storage类存储协议，该类存储设备构架于USB2．0协议之上，将存储命令嵌于USB协议之中。采用MAX3421作为USB外设控制器，MCF52233作为主控制器，通过SPI接口实现两者的通讯。试验结果表明，当MCF52233主频为60MHZ时，存储速度可以达到1．87Mbyte／s，满足了设备与主机数据交换速度的要求。

Research and Realization of USB Mass Storage Class Device

Aiming at the need of mass data transfer between embedded devices and host computer, a USB Mass Storage class device is designed by SD card, MAX3421 and MCF52233. The data transferred between embedded device and host computer is strictly complied with the USB2.0 specification and the USB Mass Storage Class Bulk-Only Transport specification, the Bulk-Only Transport specification is based on USB2.0 specification, sending and receiving storage command via USB transport. The MAX3421 works as a USB peripheral controller, communicating with the MCF52233 by SPI. The experiments show that the speed comes up 1.87 Mbyte/s when the MCU works at a clock frequency of 60 MHZ, fulfilling the request of the data transferring between the embedded device and host computer.