USB大量儲存裝置設計

Abstract

週邊設備是一種與電腦相連接的裝置，用來將資料送入CPU或從CPU取出資料。早期使用平行埠(Centronics parallel port)和RS-232(Serial port)介面和主機溝通。隨著時代的進步，電腦的資料處裡速度加快，舊介面反而不敷使用，新的介面因此產生--通用串列匯流排((USB, Universal Serial Bus)。 USB突破以往的限制，不僅具備較快的通訊速度，而且富有彈性，取代了週邊設備所使用的介面。 所謂的大量儲存裝置是指一個可以儲存資料的硬體。無論是任何裝置，都需要一個部份來存放資料。一般電腦使用硬碟儲存資料，卻無法作資料分享。 本篇論文使用序列匯流排(USB)作為大量儲存裝置和主機的溝通管道。在此選用CYPRESS CY7C3686發展系統來實現USB傳輸。至於存放資料的部份，則使用快閃記憶體(NAND FLASH MEMORY)。 USB大量儲存裝置的設計包含三大部分： 1.裝置和主機的通信介面： 本論文使用USB2.0通信介面和巨量型傳輸。USB2.0可分成高速 480Mbps)和全速(12Mbps)兩種。 2.裝置和主機的溝通語法： 主機和裝置間的指令，使用小型電腦系統介面(SCSI)。 3.存取裝置資料的方法： 儲存裝置中皆會有一顆控制器，對外部邏輯元件下達指令。利用CYPRESS晶片中的控制程序介面(GPIF,General Programmable Interface)控制快閃記憶體(NAND FLASH MEMORY)的資料讀取和寫入。

In the early times, Centronics Parallel Port and Serial Port are used to communicate with PC. By using these interfaces, data can be transferred between PC and devices. As the time go by, Central Processing Unit performs much better than before, old interface, Centronics Parallel Port and Serial Port, can not reach the speed anymore.In order to solve this problem, a new interface was invented. The Universal Serial Bus is fast and flexible interface for connecting devices to computer. A mass storage device is a hardware which can provide access to data. Every time we load an application or save a file on a hard disk, its data can not share with other computers.

This thesis describes USB mass storage device by using CY3686 USB development system manufactured by CYPRESS is used to realize USB transfer ,and stores data in NAND Flash Memory. USB mass storage device must implement these protocols and structures： 1. Generic USB protocol.This thesis describes USB 2.0 and use Bulk transfer.The USB 2.0 specification defines high speed at 480 megabits/sec and full speed at 12 megabits/sec. 2. SCSI command.USB hosts access mass storage devices via commands originally developed for devices that use Small Computer Systems Interface. 3. Flash memory protocol. The storage media's controller typically supports a command set for accessing the media's contents.By using CYPRESS special interface (GPIF,General Programmable Interface),it will be easier to control NAND Flash Memory.