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<div id="pf1" class="pf w0 h0" data-page-no="1"><div class="pc pc1 w0 h0"><img class="bi x0 y0 w1 h1" alt="" src="https://static.pudn.com/prod/directory_preview_static/633bb3d72aaf6043c9e80983/bg1.jpg"><div class="t m0 x1 h2 y1 ff1 fs0 fc0 sc0 ls0 ws0">清华大学毕业设计论文<span class="ff2"> </span></div><div class="t m0 x2 h3 y2 ff3 fs0 fc0 sc1 ls1 ws0">第一章<span class="ff4 sc0 ls0"> <span class="_ _0"> </span></span><span class="ls0">前<span class="ff4 sc0"> <span class="_ _1"> </span></span>言<span class="ff4 sc0"> </span></span></div><div class="t m0 x3 h4 y3 ff3 fs1 fc0 sc0 ls0 ws0">当今的计算机外部设备<span class="_"> </span>都在追求高速度和高通用性<span class="_"> </span>为了满足用户的需求</div><div class="t m0 x4 h5 y4 ff3 fs1 fc0 sc0 ls0 ws0">以<span class="_ _2"> </span><span class="ff2 ls2">Intel<span class="_"> </span></span><span class="ls3">为首的七家公司于<span class="_ _2"> </span></span><span class="ff2">1994<span class="_"> </span></span>年推出了<span class="_ _2"> </span><span class="ff2 ls4">USB<span class="_ _3"> </span><span class="ls5 ws1">Universal Serial Bus<span class="_ _3"> </span></span></span>通用串行总</div><div class="t m0 x4 h5 y5 ff3 fs1 fc0 sc0 ls0 ws0">线<span class="_"> </span>总线协议<span class="_"> </span>专用于低<span class="_"> </span>中速的计算机外设<span class="_"> </span>目前<span class="_"> </span><span class="ff2 ls4">USB<span class="_ _4"> </span></span>端口已成为了微机主</div><div class="t m0 x4 h4 y6 ff3 fs1 fc0 sc0 ls6 ws0">板的标准端口</div><div class="t m0 x5 h4 y7 ff3 fs1 fc0 sc0 ls7 ws0">而在不久的将来<span class="_"> </span><span class="ls8">所有的微机外设<span class="_"> </span><span class="ls9">包括键盘<span class="_"> </span><span class="lsa">鼠标<span class="_"> </span></span></span></span>显示器</div><div class="t m0 x4 h5 y8 ff3 fs1 fc0 sc0 ls0 ws0">打印机<span class="_"> </span>数字相机<span class="_"> </span>扫描仪和游戏柄等等<span class="_"> </span>都将通过<span class="_ _2"> </span><span class="ff2 lsb">USB<span class="_"> </span></span>与主机相连<span class="_"> </span><span class="lsc">这种连接</span></div><div class="t m0 x4 h4 y9 ff3 fs1 fc0 sc0 lsd ws0">较以往普通并口和串口的连接而言<span class="_"> </span>主要的优点是速度高<span class="_"> </span><span class="ls7">功耗低<span class="_"> </span><span class="lse">支持即插即</span></span></div><div class="t m0 x4 h5 ya ff3 fs1 fc0 sc0 ls0 ws0">用<span class="_"> </span><span class="ff2 lsf ws2">Plug & Play<span class="_ _3"> </span></span>和使用维护方便<span class="_"> </span><span class="ff2"> </span></div><div class="t m0 x4 h5 yb ff2 fs1 fc0 sc0 ls0 ws0"> <span class="_ _5"> </span><span class="ff3">作为一个硬件厂商或是开发者<span class="_"> </span>最关心的便是如何去开发<span class="_ _6"> </span></span><span class="ls4">USB<span class="_ _6"> </span></span><span class="ff3">外设<span class="_"> </span>一般的</span></div><div class="t m0 x4 h5 yc ff2 fs1 fc0 sc0 ls4 ws0">USB<span class="_ _4"> </span><span class="ff3 ls10">设备都使用一片微控制器作为其核心部件<span class="_"> </span><span class="ls0">通过微控制器强大的控制和运算</span></span></div><div class="t m0 x4 h4 yd ff3 fs1 fc0 sc0 ls0 ws0">功能</div><div class="t m0 x6 h5 ye ff3 fs1 fc0 sc0 ls0 ws0">开发者可以很容易地实现<span class="_ _2"> </span><span class="ff2 ls4">USB<span class="_"> </span></span>设备的智能化<span class="_"> </span><span class="ff2"> </span></div><div class="t m0 x3 h5 yf ff2 fs1 fc0 sc0 ls11 ws0">MOT<span class="_ _7"></span>OROLA<span class="_"> </span><span class="ff3 ls0">公司是目前世界上最大的微控制器供应商<span class="_ _8"> </span>其<span class="_ _2"> </span><span class="ff2">8<span class="_"> </span></span>位微控制器的全</span></div><div class="t m0 x4 h5 y10 ff3 fs1 fc0 sc0 ls0 ws0">球市场份额达到了<span class="_ _6"> </span><span class="ff2">30%</span>左右<span class="_"> </span><span class="ff2 ls12">MOTOROLA<span class="_ _6"> </span></span>公司将其<span class="_ _6"> </span><span class="ff2">8<span class="_ _6"> </span></span><span class="ls13">位微控制器归类为用户定</span></div><div class="t m0 x4 h5 y11 ff3 fs1 fc0 sc0 ls0 ws0">制的集成电路<span class="_ _9"> </span><span class="ff2 ls14">CSIC<span class="_ _a"> </span></span>为客户提供了<span class="_ _2"> </span><span class="ff2 ls15">MPU<span class="_ _9"> </span><span class="ls16">RAM<span class="_ _9"> </span><span class="ls17">EPROM<span class="_ _9"> </span><span class="ls18">SPI<span class="_ _9"> </span></span>SCI<span class="_ _9"> </span></span></span></span><span class="ls19">定时器</span></div><div class="t m0 x4 h5 y12 ff3 fs1 fc0 sc0 ls0 ws0">和<span class="_ _2"> </span><span class="ff2 ls4">USB<span class="_"> </span></span><span class="ls1a">等多种模块<span class="_"> </span></span>用量大的客户可以根据自己的需要选择不同的模块来构筑自</div><div class="t m0 x4 h5 y13 ff3 fs1 fc0 sc0 ls0 ws0">己的微控制器<span class="_ _b"> </span><span class="ff2 ls1b">MOTOROLA<span class="_"> </span></span><span class="ls1c">公司从<span class="_ _2"> </span></span><span class="ff2">1996<span class="_"> </span></span>年开始<span class="_ _8"> </span>陆续推出了一系列含有<span class="_ _2"> </span><span class="ff2 lsb">US<span class="_ _c"></span>B<span class="_"> </span></span>模</div><div class="t m0 x4 h5 y14 ff3 fs1 fc0 sc0 ls1d ws0">块的<span class="_ _4"> </span><span class="ff2 ls0">8<span class="_ _d"> </span></span><span class="ls1e">位微控制器</span></div><div class="t m0 x7 h5 y15 ff3 fs1 fc0 sc0 ls1f ws0">用于支持<span class="_ _4"> </span><span class="ff2 lsb">USB<span class="_ _d"> </span></span><span class="ls20">总线协议的设备<span class="_"> </span><span class="ls21">如最早的用于显示器的</span></span></div><div class="t m0 x4 h5 y16 ff2 fs1 fc0 sc0 ls14 ws0">68HC05BD9A<span class="_ _e"> </span><span class="ff3 ls22">用于鼠标的<span class="_ _4"> </span></span><span class="ls23">68HC05JB2<span class="_ _e"> </span><span class="ff3 ls24">以及用于键盘的<span class="_ _d"> </span></span><span class="ls25">68HC08KL8<span class="_ _f"> </span><span class="ff3 ls0">和</span></span></span></div><div class="t m0 x4 h5 y17 ff2 fs1 fc0 sc0 ls14 ws0">68HC08KH12<span class="_"> </span><span class="ff3 ls0">等等<span class="_ _10"> </span>通过微控制器内含的<span class="_ _2"> </span></span><span class="lsb">USB<span class="_"> </span><span class="ff3 ls0">模块<span class="_ _10"> </span>用户可以很方便地实现<span class="_ _2"> </span></span><span class="ls4">USB</span></span></div><div class="t m0 x4 h4 y18 ff3 fs1 fc0 sc0 ls0 ws0">总线上的数据通讯</div><div class="t m0 x8 h5 y19 ff2 fs1 fc0 sc0 ls26 ws0">68HC05JB4<span class="_"> </span><span class="ff3 ls0">最初是用于开发<span class="_ _2"> </span></span><span class="ls4">USB<span class="_"> </span><span class="ff3 ls0">游戏柄的<span class="_ _11"> </span>后来也常被用于</span></span></div><div class="t m0 x4 h5 y1a ff3 fs1 fc0 sc0 ls0 ws0">其他一些<span class="_ _2"> </span><span class="ff2 ls4">USB<span class="_"> </span></span>外设的开发<span class="_"> </span><span class="ff2"> </span></div><div class="t m0 x3 h5 y1b ff3 fs1 fc0 sc0 ls0 ws0">国外在近两年已出现了不少的<span class="_ _6"> </span><span class="ff2 ls4">USB<span class="_ _6"> </span></span>外设<span class="_"> </span>但目前在国内市场上我们仅发现了</div><div class="t m0 x4 h5 y1c ff3 fs1 fc0 sc0 ls0 ws0">台湾生产的摄像头等少数几类高速<span class="_ _2"> </span><span class="ff2 ls4">USB<span class="_"> </span></span><span class="ls27">外设<span class="_ _8"> </span></span>低速<span class="_ _2"> </span><span class="ff2 lsf">USB<span class="_"> </span></span><span class="ls28">设备还是一个空白<span class="_ _8"> </span></span>同时</div><div class="t m0 x4 h5 y1d ff3 fs1 fc0 sc0 ls0 ws0">国外开发的<span class="_ _2"> </span><span class="ff2 ls4">USB<span class="_"> </span></span><span class="ls28">设备多集中在鼠标<span class="_ _8"> </span></span>键盘等少数几类设备上<span class="_ _8"> </span>诸如<span class="_ _2"> </span><span class="ff2 ls4">USB<span class="_ _2"> </span></span><span class="ls18">手写板等</span></div><div class="t m0 x4 h4 y1e ff3 fs1 fc0 sc0 ls0 ws0">设备就是在国外也很少见<span class="_ _12"> </span>国内近年来计算机非键盘输入技术发展很快<span class="_ _12"> </span>在汉字</div><div class="t m0 x4 h5 y1f ff3 fs1 fc0 sc0 ls0 ws0">英文和数字的手写识别方面已有相当基础<span class="_"> </span>本项目之目的<span class="_"> </span>就是吸收<span class="_ _2"> </span><span class="ff2 ls4">USB<span class="_"> </span></span><span class="ls1c">总线和</span></div><div class="t m0 x4 h5 y20 ff2 fs1 fc0 sc0 ls11 ws0">MOT<span class="_ _7"></span>OROLA<span class="_"> </span><span class="ff3 ls0">微控制器的先进技术<span class="_ _d"> </span>与中科院自动化所汉王公司的手写识别技术相</span></div><div class="t m0 x4 h5 y21 ff3 fs1 fc0 sc0 ls0 ws0">结合<span class="_"> </span>在汉王笔的基础上<span class="_"> </span>设计生产出自己的新一代<span class="_ _2"> </span><span class="ff2 ls4">USB<span class="_"> </span></span>手写输入系统<span class="_"> </span><span class="ff2"> </span></div><div class="t m0 x4 h5 y22 ff2 fs1 fc0 sc0 ls0 ws0"> <span class="_ _5"> </span><span class="ff3">此<span class="_ _2"> </span></span><span class="ls4">USB<span class="_"> </span><span class="ff3 ls18">手写系统<span class="_"> </span><span class="ls0">采用汉王公司的传感器获得笔画信息<span class="_"> </span>传给<span class="_ _13"> </span></span></span><span class="ls26">68HC05JB4</span></span></div><div class="t m0 x4 h5 y23 ff3 fs1 fc0 sc0 ls0 ws0">经过整理后通过<span class="_ _2"> </span><span class="ff2 ls4">USB<span class="_"> </span></span>总线发送到<span class="_ _2"> </span><span class="ff2 ls1b">PC<span class="_ _8"> </span></span>再由自行编写的驱动程序接收<span class="_ _8"> </span>最终转给汉</div><div class="t m0 x4 h5 y24 ff3 fs1 fc0 sc0 ls0 ws0">王公司的文字识别软件识别<span class="_"> </span><span class="ff2"> </span></div><div class="t m0 x4 h6 y25 ff2 fs2 fc0 sc0 ls29 ws0"> </div><div class="t m0 x4 h6 y26 ff2 fs2 fc0 sc0 ls29 ws0"> </div><div class="t m0 x9 h7 y27 ff3 fs3 fc0 sc0 ls0 ws0">第</div><div class="t m0 xa h8 y28 ff2 fs3 fc0 sc0 ls2a ws3"> 1 </div><div class="t m0 xb h7 y27 ff3 fs3 fc0 sc0 ls0 ws0">页</div><div class="t m0 xc h8 y28 ff2 fs3 fc0 sc0 ls0 ws0"> </div></div><div class="pi" data-data='{"ctm":[1.611639,0.000000,0.000000,1.611639,0.000000,0.000000]}'></div></div>
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<div id="pf2" class="pf w0 h0" data-page-no="2"><div class="pc pc2 w0 h0"><img class="bi x0 y0 w1 h1" alt="" src="https://static.pudn.com/prod/directory_preview_static/633bb3d72aaf6043c9e80983/bg2.jpg"><div class="t m0 x1 h2 y1 ff1 fs0 fc0 sc0 ls0 ws0">清华大学毕业设计论文<span class="ff2"> </span></div><div class="t m0 xd h9 y2 ff3 fs0 fc0 sc1 ls2b ws0">第二章<span class="ff5 ls0"> <span class="_ _b"> </span><span class="ff4 sc0 ls2c">USB<span class="_"> </span></span></span><span class="ls2d">总线协议<span class="ff4 sc0 ls0"> </span></span></div><div class="t m0 xe h5 y29 ff2 fs1 fc0 sc0 ls4 ws0">USB<span class="_ _11"> </span><span class="ls2e ws4">Universal Serial Bus</span></div><div class="t m0 xf h4 y3 ff3 fs1 fc0 sc0 ls0 ws0">总线协议是以</div><div class="t m0 x10 h5 y2a ff2 fs1 fc0 sc0 ls2f ws0">Intel</div><div class="t m0 x11 h4 y3 ff3 fs1 fc0 sc0 ls0 ws0">为主<span class="_ _11"> </span><span class="ls30">并有</span></div><div class="t m0 x12 h5 y2a ff2 fs1 fc0 sc0 ls31 ws0">Compaq</div><div class="t m0 x13 h5 y29 ff2 fs1 fc0 sc0 ls32 ws0">Microsoft</div><div class="t m0 x4 h5 y2b ff2 fs1 fc0 sc0 ls0 ws0">IBM<span class="_ _3"> </span><span class="ls33">DEC<span class="_ _3"> </span><span class="lsf ws5">Northern T<span class="_ _14"></span>elecom</span></span></div><div class="t m0 x14 h4 y2c ff3 fs1 fc0 sc0 ls18 ws0">以及日本</div><div class="t m0 x15 h5 y2b ff2 fs1 fc0 sc0 ls33 ws0">NEC</div><div class="t m0 x16 h4 y2c ff3 fs1 fc0 sc0 ls0 ws0">等共七家公司共同制定的串行接口标</div><div class="t m0 x4 h4 y2d ff3 fs1 fc0 sc0 ls0 ws0">准</div><div class="t m0 x17 h5 y2e ff2 fs1 fc0 sc0 ls0 ws0">1994</div><div class="t m0 x18 h4 y2d ff3 fs1 fc0 sc0 ls0 ws0">年</div><div class="t m0 x19 h5 y2e ff2 fs1 fc0 sc0 ls34 ws0">11</div><div class="t m0 x1a h4 y2d ff3 fs1 fc0 sc0 ls0 ws0">月制定了第一个草案</div><div class="t m0 x1b h5 y2e ff2 fs1 fc0 sc0 ls0 ws0">1996</div><div class="t m0 x1c h4 y2d ff3 fs1 fc0 sc0 ls0 ws0">年</div><div class="t m0 x1d h5 y2e ff2 fs1 fc0 sc0 ls0 ws0">2</div><div class="t m0 x1e h4 y2d ff3 fs1 fc0 sc0 ls0 ws0">月公布了</div><div class="t m0 x1f h5 y2e ff2 fs1 fc0 sc0 ls4 ws0">USB</div><div class="t m0 x20 h4 y2d ff3 fs1 fc0 sc0 lsc ws0">规范版本</div><div class="t m0 x21 h5 y2e ff2 fs1 fc0 sc0 ls0 ws0">1.0<span class="_ _9"> </span><span class="ls4">USB</span></div><div class="t m0 x22 h4 y2d ff3 fs1 fc0 sc0 ls0 ws0">可把</div><div class="t m0 x4 h4 y7 ff3 fs1 fc0 sc0 ls0 ws0">多达</div><div class="t m0 x23 h5 y2f ff2 fs1 fc0 sc0 ls0 ws0">127</div><div class="t m0 x24 h4 y7 ff3 fs1 fc0 sc0 ls0 ws0">个外设同时联到你的系统上<span class="_"> </span>所有的外设通过协议来共享</div><div class="t m0 x25 h5 y2f ff2 fs1 fc0 sc0 ls4 ws0">USB</div><div class="t m0 x26 h4 y7 ff3 fs1 fc0 sc0 ls0 ws0">的带宽<span class="_"> </span>其</div><div class="t m0 x4 h5 y30 ff2 fs1 fc0 sc0 ls2f ws0">12Mbps</div><div class="t m0 x27 h4 y8 ff3 fs1 fc0 sc0 ls27 ws0">的带宽对于键盘<span class="_"> </span>鼠标等低中速外设是完全足够的<span class="_ _5"> </span><span class="ls0">注<span class="_"> </span>在</span></div><div class="t m0 x28 h5 y31 ff2 fs1 fc0 sc0 ls0 ws0">1999</div><div class="t m0 x29 h4 y8 ff3 fs1 fc0 sc0 ls0 ws0">年</div><div class="t m0 x2a h5 y31 ff2 fs1 fc0 sc0 ls0 ws0">2</div><div class="t m0 x22 h4 y8 ff3 fs1 fc0 sc0 ls27 ws0">月发</div><div class="t m0 x4 h4 y9 ff3 fs1 fc0 sc0 ls0 ws0">布的</div><div class="t m0 x23 h5 y32 ff2 fs1 fc0 sc0 ls4 ws0">USB</div><div class="t m0 x18 h4 y9 ff3 fs1 fc0 sc0 ls18 ws0">规范版本</div><div class="t m0 x2b h5 y32 ff2 fs1 fc0 sc0 ls0 ws0">2.0</div><div class="t m0 x2c h4 y9 ff3 fs1 fc0 sc0 ls0 ws0">草案中<span class="_ _9"> </span>已建议将</div><div class="t m0 x2d h5 y32 ff2 fs1 fc0 sc0 ls2f ws0">12Mbps</div><div class="t m0 x2e h4 y9 ff3 fs1 fc0 sc0 ls0 ws0">的带宽提升到</div><div class="t m0 x2f h5 y32 ff2 fs1 fc0 sc0 ls10 ws0">120-240Mbps</div><div class="t m0 x30 h5 y33 ff2 fs1 fc0 sc0 ls4 ws0">USB</div><div class="t m0 x4 h4 ya ff3 fs1 fc0 sc0 ls35 ws0">允许外设在主机和其它<span class="ls36">外设工作时进行连接<span class="_"> </span><span class="lsa">配置<span class="_"> </span><span class="lse">使用及移除<span class="_"> </span><span class="lsd">即所谓的即插</span></span></span></span></div><div class="t m0 x4 h4 yb ff3 fs1 fc0 sc0 ls0 ws0">即用</div><div class="t m0 x31 h5 y34 ff2 fs1 fc0 sc0 lsf ws2">Plug & Play</div><div class="t m0 x32 h4 yb ff3 fs1 fc0 sc0 ls0 ws0">同时</div><div class="t m0 x33 h5 y35 ff2 fs1 fc0 sc0 ls4 ws0">USB</div><div class="t m0 x34 h4 yb ff3 fs1 fc0 sc0 ls28 ws0">总线的应用可以清除</div><div class="t m0 x35 h5 y35 ff2 fs1 fc0 sc0 ls1b ws0">PC</div><div class="t m0 x36 h4 yb ff3 fs1 fc0 sc0 ls0 ws0">上过多的</div><div class="t m0 x37 h5 y35 ff2 fs1 fc0 sc0 ls31 ws0">I/O</div><div class="t m0 x38 h4 yb ff3 fs1 fc0 sc0 ls0 ws0">端口<span class="_ _10"> </span><span class="ls18">而以一个</span></div><div class="t m0 x4 h4 yc ff3 fs1 fc0 sc0 ls0 ws0">串行通道取代<span class="_"> </span>使</div><div class="t m0 x39 h5 y36 ff2 fs1 fc0 sc0 ls1b ws0">PC</div><div class="t m0 x2c h4 yc ff3 fs1 fc0 sc0 ls0 ws0">与外设之间的连接更容易</div><div class="t m0 x3a h5 y37 ff2 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 xe h4 ye ff3 fs1 fc0 sc0 ls0 ws0">以下简单介绍</div><div class="t m0 x3b h5 y38 ff2 fs1 fc0 sc0 ls4 ws0">USB</div><div class="t m0 x7 h4 ye ff3 fs1 fc0 sc0 ls1a ws0">总线的结构<span class="_ _15"> </span><span class="ls0">原理<span class="_ _15"> </span>以使读者对</span></div><div class="t m0 x3c h5 y38 ff2 fs1 fc0 sc0 ls4 ws0">USB</div><div class="t m0 x3d h4 ye ff3 fs1 fc0 sc0 lsf ws0">有大致的了解<span class="_ _15"> </span><span class="ls0">如果需</span></div><div class="t m0 x4 h4 yf ff3 fs1 fc0 sc0 ls0 ws0">要了解其协议细节<span class="_"> </span>请查阅</div><div class="t m0 x3e h5 y39 ff2 fs1 fc0 sc0 ls4 ws0">USB</div><div class="t m0 xf h4 yf ff3 fs1 fc0 sc0 ls0 ws0">总线规范<span class="_"> </span>这可以从</div><div class="t m0 x3f h5 y39 ff2 fs1 fc0 sc0 ls3 ws0">www<span class="_ _14"></span>.usb.org</div><div class="t m0 x40 h4 yf ff3 fs1 fc0 sc0 ls0 ws0">下载</div><div class="t m0 x41 h5 y3a ff2 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 x4 h3 y3b ff4 fs0 fc0 sc0 ls37 ws0">2.1 <span class="_ _8"> </span><span class="ff3 sc1 ls2d">总线拓扑结构</span><span class="ls0"> </span></div><div class="t m0 xe h5 y3c ff2 fs1 fc0 sc0 ls4 ws0">USB</div><div class="t m0 x42 h4 y3d ff3 fs1 fc0 sc0 ls38 ws0">总线的物理连接是一种分层的菊花链结构</div><div class="t m0 x43 h4 y3e ff3 fs1 fc0 sc0 lsa ws0">集线器</div><div class="t m0 x44 h5 y3f ff2 fs1 fc0 sc0 ls3 ws0">(hub)</div><div class="t m0 x45 h4 y3e ff3 fs1 fc0 sc0 lsa ws0">是每个星形结构</div><div class="t m0 x4 h4 y40 ff3 fs1 fc0 sc0 ls0 ws0">的中心</div><div class="t m0 x18 h5 y41 ff2 fs1 fc0 sc0 ls39 ws0">PC</div><div class="t m0 x46 h4 y42 ff3 fs1 fc0 sc0 ls0 ws0">机就是主机和根</div><div class="t m0 x47 h5 y41 ff2 fs1 fc0 sc0 ls3a ws0">Hub</div><div class="t m0 x48 h4 y40 ff3 fs1 fc0 sc0 ls0 ws0">用户可以将外设或附加的</div><div class="t m0 x49 h5 y43 ff2 fs1 fc0 sc0 ls3a ws0">Hub</div><div class="t m0 x4a h4 y40 ff3 fs1 fc0 sc0 ls0 ws0">与之相连<span class="_ _11"> </span><span class="ls1c">这些附</span></div><div class="t m0 x4 h4 y44 ff3 fs1 fc0 sc0 ls3b ws0">加的</div><div class="t m0 x23 h5 y45 ff2 fs1 fc0 sc0 ls3a ws0">Hub</div><div class="t m0 x4b h4 y44 ff3 fs1 fc0 sc0 ls3c ws0">可以连接另外的外设以及下层</div><div class="t m0 x4c h5 y45 ff2 fs1 fc0 sc0 ls3a ws0">Hub</div><div class="t m0 x4d h5 y46 ff2 fs1 fc0 sc0 ls4 ws0">USB</div><div class="t m0 x4e h4 y47 ff3 fs1 fc0 sc0 ls3d ws0">支持最多</div><div class="t m0 x4f h5 y46 ff2 fs1 fc0 sc0 ls0 ws0">5</div><div class="t m0 x44 h4 y47 ff3 fs1 fc0 sc0 ls0 ws0">个</div><div class="t m0 x50 h5 y46 ff2 fs1 fc0 sc0 ls3a ws0">Hub</div><div class="t m0 x51 h4 y47 ff3 fs1 fc0 sc0 ls3b ws0">层以及</div><div class="t m0 x29 h5 y46 ff2 fs1 fc0 sc0 ls0 ws0">127</div><div class="t m0 x22 h4 y47 ff3 fs1 fc0 sc0 ls3b ws0">个外</div><div class="t m0 x4 h4 y48 ff3 fs1 fc0 sc0 ls0 ws0">设<span class="_ _10"> </span>图</div><div class="t m0 x31 h5 y49 ff2 fs1 fc0 sc0 ls0 ws0">2.1</div><div class="t m0 x52 h4 y48 ff3 fs1 fc0 sc0 ls0 ws0">描述了</div><div class="t m0 x5 h5 y49 ff2 fs1 fc0 sc0 ls4 ws0">USB</div><div class="t m0 x32 h4 y48 ff3 fs1 fc0 sc0 ls0 ws0">的物理拓扑结构<span class="_ _10"> </span>从中可以看出每一段的连接都是点对点的</div><div class="t m0 x53 h5 y4a ff2 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 x54 h5 y4b ff2 fs1 fc0 sc0 ls3e ws0"> </div><div class="t m0 x55 ha y4c ff6 fs4 fc0 sc0 ls3f ws6">Host (Root Tier)</div><div class="t m0 x56 ha y4d ff6 fs4 fc0 sc0 ls40 ws7">Tier 1</div><div class="t m0 x57 ha y4e ff6 fs4 fc0 sc0 ls40 ws7">Tier 2</div><div class="t m0 x58 ha y4f ff6 fs4 fc0 sc0 ls40 ws7">Tier 3</div><div class="t m0 x59 ha y50 ff6 fs4 fc0 sc0 ls40 ws7">Tier 4</div><div class="t m0 x5a hb y51 ff6 fs5 fc0 sc0 ls41 ws8">Hub 1</div><div class="t m0 x5b hb y52 ff6 fs5 fc0 sc0 ls41 ws8">Hub 2</div><div class="t m0 x5c hb y53 ff6 fs5 fc0 sc0 ls41 ws0">Node</div><div class="t m0 x5a hb y54 ff6 fs5 fc0 sc0 ls42 ws0">Host</div><div class="t m0 x5d hc y55 ff6 fs6 fc0 sc0 ls43 ws0">RootHub</div><div class="t m0 x5e hb y56 ff6 fs5 fc0 sc0 ls41 ws0">Node</div><div class="t m0 x47 hb y57 ff6 fs5 fc0 sc0 ls41 ws8">Hub 3</div><div class="t m0 x5f hb y58 ff6 fs5 fc0 sc0 ls41 ws8">Hub 4</div><div class="t m0 x60 hb y59 ff6 fs5 fc0 sc0 ls41 ws0">Node</div><div class="t m0 x10 hb y5a ff6 fs5 fc0 sc0 ls41 ws0">Node</div><div class="t m0 x61 hb y5b ff6 fs5 fc0 sc0 ls41 ws0">Node</div><div class="t m0 x62 hb y5c ff6 fs5 fc0 sc0 ls41 ws0">Node</div><div class="t m0 x63 hb y5d ff6 fs5 fc0 sc0 ls41 ws0">Node</div><div class="t m0 x25 h5 y5e ff2 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 xf h4 y5f ff3 fs1 fc0 sc0 ls0 ws0">图</div><div class="t m0 x64 h5 y60 ff2 fs1 fc0 sc0 ls3 ws9">2.1 USB</div><div class="t m0 x1e h4 y5f ff3 fs1 fc0 sc0 ls0 ws0">总线拓扑</div><div class="t m0 x1f h5 y60 ff2 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 x4 h6 y25 ff2 fs2 fc0 sc0 ls29 ws0"> </div><div class="t m0 x4 h6 y26 ff2 fs2 fc0 sc0 ls29 ws0"> </div><div class="t m0 x9 h7 y27 ff3 fs3 fc0 sc0 ls0 ws0">第</div><div class="t m0 xa h8 y28 ff2 fs3 fc0 sc0 ls2a ws3"> 2 </div><div class="t m0 xb h7 y27 ff3 fs3 fc0 sc0 ls0 ws0">页</div><div class="t m0 xc h8 y28 ff2 fs3 fc0 sc0 ls0 ws0"> </div></div><div class="pi" data-data='{"ctm":[1.611639,0.000000,0.000000,1.611639,0.000000,0.000000]}'></div></div>
<div id="pf3" class="pf w0 h0" data-page-no="3"><div class="pc pc3 w0 h0"><img class="bi x0 y0 w1 h1" alt="" src="https://static.pudn.com/prod/directory_preview_static/633bb3d72aaf6043c9e80983/bg3.jpg"><div class="t m0 x1 h2 y1 ff1 fs0 fc0 sc0 ls0 ws0">清华大学毕业设计论文<span class="ff2"> </span></div><div class="t m0 x4 h3 y61 ff4 fs0 fc0 sc0 ls44 wsa">2.2 USB<span class="ff3 sc1 ls2d ws0">的物理层</span><span class="ls0 ws0"> </span></div><div class="t m0 xe h5 y62 ff2 fs1 fc0 sc0 ls4 ws0">USB</div><div class="t m0 x42 h4 y63 ff3 fs1 fc0 sc0 ls0 ws0">的物理接口包括电气特性和机械特性</div><div class="t m0 x65 h5 y62 ff2 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 xe h5 y64 ff2 fs1 fc0 sc0 ls4 ws0">USB</div><div class="t m0 x42 h4 y65 ff3 fs1 fc0 sc0 ls0 ws0">通过一个四线电缆来传输信号与电源</div><div class="t m0 x65 h4 y66 ff3 fs1 fc0 sc0 ls0 ws0">如图</div><div class="t m0 x66 h5 y67 ff2 fs1 fc0 sc0 ls0 ws0">2.2</div><div class="t m0 x67 h4 y66 ff3 fs1 fc0 sc0 ls0 ws0">所示</div><div class="t m0 x68 h5 y64 ff2 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 xe h5 y68 ff2 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 x69 hd y69 ff2 fs7 fc0 sc0 ls0 ws0">...</div><div class="t m0 x69 hd y6a ff2 fs7 fc0 sc0 ls0 ws0">...</div><div class="t m0 x6a he y6b ff2 fs8 fc0 sc0 ls45 wsb">5 meters ma<span class="_ _c"></span>x</div><div class="t m0 x6b hf y6c ff2 fs9 fc0 sc0 ls46 ws0">VBus</div><div class="t m0 x6c hf y6d ff2 fs9 fc0 sc0 ls46 ws0">GND</div><div class="t m0 x6d hf y6e ff2 fs9 fc0 sc0 ls46 ws0">D+</div><div class="t m0 x6d hf y6f ff2 fs9 fc0 sc0 ls46 ws0">D-</div><div class="t m0 x6e hf y70 ff2 fs9 fc0 sc0 ls46 ws0">VBus</div><div class="t m0 x6f hf y71 ff2 fs9 fc0 sc0 ls46 ws0">GND</div><div class="t m0 x6f hf y72 ff2 fs9 fc0 sc0 ls46 ws0">D+</div><div class="t m0 x6f hf y73 ff2 fs9 fc0 sc0 ls46 ws0">D-</div><div class="c x70 y74 w2 h10"><div class="t m1 x71 h11 y75 ff7 fsa fc0 sc0 ls0 ws0"><span class="fc1 sc0"></span></div><div class="t m1 x71 h11 y76 ff7 fsa fc0 sc0 ls0 ws0"><span class="fc1 sc0"></span></div><div class="t m1 x71 h11 y77 ff7 fsa fc0 sc0 ls0 ws0"><span class="fc1 sc0"></span></div><div class="t m1 x71 h11 y78 ff7 fsa fc0 sc0 ls0 ws0"><span class="fc1 sc0"></span></div><div class="t m1 x71 h11 y79 ff7 fsa fc0 sc0 ls0 ws0"><span class="fc1 sc0"></span></div><div class="t m1 x71 h11 y7a ff7 fsa fc0 sc0 ls0 ws0"><span class="fc1 sc0"></span></div><div class="t m1 x71 h11 y7b ff7 fsa fc0 sc0 ls0 ws0"><span class="fc1 sc0"></span></div></div><div class="t m0 x72 h5 y7c ff2 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 x73 h5 y7d ff2 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 xf h4 y7e ff3 fs1 fc0 sc0 ls0 ws0">图</div><div class="t m0 x64 h5 y7f ff2 fs1 fc0 sc0 ls3 ws9">2.2 USB</div><div class="t m0 x1e h4 y7e ff3 fs1 fc0 sc0 ls0 ws0">电缆定义</div><div class="t m0 x1f h5 y7f ff2 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 x74 h5 y80 ff2 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 xe h4 y81 ff3 fs1 fc0 sc0 ls0 ws0">其中</div><div class="t m0 x42 h5 y82 ff2 fs1 fc0 sc0 lsb ws0">D+</div><div class="t m0 x46 h4 y81 ff3 fs1 fc0 sc0 ls0 ws0">和</div><div class="t m0 x75 h5 y82 ff2 fs1 fc0 sc0 ls47 ws0">D-</div><div class="t m0 x76 h4 y81 ff3 fs1 fc0 sc0 ls0 ws0">是一对差模的信号线<span class="_ _8"> </span>而</div><div class="t m0 x69 h5 y82 ff2 fs1 fc0 sc0 ls3a ws0">VBus</div><div class="t m0 x77 h4 y81 ff3 fs1 fc0 sc0 ls0 ws0">和</div><div class="t m0 x78 h5 y82 ff2 fs1 fc0 sc0 lsb ws0">GND</div><div class="t m0 x79 h4 y81 ff3 fs1 fc0 sc0 ls18 ws0">则提供了</div><div class="t m0 x25 h5 y83 ff2 fs1 fc0 sc0 ls0 ws0">5V</div><div class="t m0 x7a h4 y84 ff3 fs1 fc0 sc0 ls0 ws0">的电源</div><div class="t m0 x22 h4 y81 ff3 fs1 fc0 sc0 ls0 ws0">它可</div><div class="t m0 x4 h4 y85 ff3 fs1 fc0 sc0 ls0 ws0">以给一些设备</div><div class="t m0 x7b h5 y86 ff2 fs1 fc0 sc0 ls0 ws0">(</div><div class="t m0 x6f h4 y85 ff3 fs1 fc0 sc0 ls0 ws0">包括</div><div class="t m0 x7c h5 y86 ff2 fs1 fc0 sc0 ls3 ws0">Hub)</div><div class="t m0 x7d h4 y85 ff3 fs1 fc0 sc0 ls0 ws0">供电<span class="_"> </span>当然要有一定的条件限制</div><div class="t m0 x7e h5 y87 ff2 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 xe h5 y88 ff2 fs1 fc0 sc0 ls4 ws0">USB</div><div class="t m0 x42 h4 y89 ff3 fs1 fc0 sc0 ls48 ws0">提供了两种数据传输率</div><div class="t m0 x64 h4 y8a ff3 fs1 fc0 sc0 ls7 ws0">一种是</div><div class="t m0 x7f h5 y8b ff2 fs1 fc0 sc0 ls10 ws0">12Mb</div><div class="t m0 x2e h4 y8a ff3 fs1 fc0 sc0 ls7 ws0">的高速</div><div class="t m0 x79 h5 y8b ff2 fs1 fc0 sc0 ls2 wsc">(full speed)</div><div class="t m0 x45 h4 y8a ff3 fs1 fc0 sc0 lsa ws0">模式<span class="_"> </span>另一种是</div><div class="t m0 x4 h5 y8c ff2 fs1 fc0 sc0 ls14 ws0">1.5Mb</div><div class="t m0 x80 h4 y8d ff3 fs1 fc0 sc0 ls0 ws0">的低速模式</div><div class="t m0 x1 h4 y8e ff3 fs1 fc0 sc0 ls0 ws0">这两种模式可以同时存在于一个</div><div class="t m0 x81 h5 y8f ff2 fs1 fc0 sc0 ls4 ws0">USB</div><div class="t m0 x58 h4 y8e ff3 fs1 fc0 sc0 ls0 ws0">系统中<span class="_ _11"> </span>而引入低速模式</div><div class="t m0 x4 h4 y90 ff3 fs1 fc0 sc0 ls0 ws0">主要是为了降低要求不高的设备的成本<span class="_"> </span>比如鼠标<span class="_"> </span>键盘等等</div><div class="t m0 x82 h5 y91 ff2 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 xe h5 y92 ff2 fs1 fc0 sc0 ls4 ws0">USB</div><div class="t m0 x42 h4 y93 ff3 fs1 fc0 sc0 ls14 ws0">信号线在高速模式下必须使用带有屏蔽的双绞线</div><div class="t m0 x4f h4 y94 ff3 fs1 fc0 sc0 ls0 ws0">而且最长不能超过</div><div class="t m0 x83 h5 y95 ff2 fs1 fc0 sc0 ls27 ws0">5m</div><div class="t m0 x4 h4 y96 ff3 fs1 fc0 sc0 ls27 ws0">而在低速模式时中可以使用不带屏蔽或不是双绞的线<span class="_"> </span>但最长不能超过</div><div class="t m0 x84 h5 y97 ff2 fs1 fc0 sc0 ls0 ws0">3m</div><div class="t m0 x22 h4 y96 ff3 fs1 fc0 sc0 ls27 ws0">这主</div><div class="t m0 x4 h4 y98 ff3 fs1 fc0 sc0 ls6 ws0">要是由于信号衰减的限制<span class="_"> </span>为了提供信号电压保证<span class="_"> </span><span class="ls35">以及与终端负载相匹配<span class="_"> </span><span class="ls0">在</span></span></div><div class="t m0 x4 h4 y99 ff3 fs1 fc0 sc0 lsd ws0">电缆的每一端都使用了不平衡的终端负载<span class="_"> </span><span class="ls36">这种终端负载也保证了能够检测外设</span></div><div class="t m0 x4 h4 y9a ff3 fs1 fc0 sc0 ls0 ws0">与端口的连接或分离<span class="_"> </span>并且可以区分高速与低速设备</div><div class="t m0 x70 h5 y9b ff2 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 xe h4 y9c ff3 fs1 fc0 sc0 ls0 ws0">所有的设备都有上行的接口</div><div class="t m0 x85 h4 y9d ff3 fs1 fc0 sc0 ls0 ws0">上行和下行的接头是不能互换的<span class="_ _8"> </span>这保证了不会</div><div class="t m0 x4 h4 y9e ff3 fs1 fc0 sc0 ls49 ws0">有非法的连接出现<span class="_"> </span><span class="ls4a">插头与插座有两个系列<span class="_"> </span><span class="ls3b">分别为</span></span></div><div class="t m0 x36 h5 y9f ff2 fs1 fc0 sc0 ls0 ws0">A</div><div class="t m0 x86 h4 y9e ff3 fs1 fc0 sc0 ls0 ws0">和</div><div class="t m0 x87 h5 y9f ff2 fs1 fc0 sc0 ls0 ws0">B</div><div class="t m0 x12 h4 y9e ff3 fs1 fc0 sc0 ls3b ws0">系列</div><div class="t m0 x88 h5 y9f ff2 fs1 fc0 sc0 ls0 ws0">A</div><div class="t m0 x89 h4 y9e ff3 fs1 fc0 sc0 ls4a ws0">用于基本固定</div><div class="t m0 x4 h4 ya0 ff3 fs1 fc0 sc0 ls0 ws0">的外围设备</div><div class="t m0 x7b h4 ya1 ff3 fs1 fc0 sc0 ls0 ws0">而系列</div><div class="t m0 x8a h5 ya2 ff2 fs1 fc0 sc0 ls0 ws0">B</div><div class="t m0 x8b h4 ya1 ff3 fs1 fc0 sc0 ls0 ws0">用于经常拔插的设备<span class="_"> </span>这两个系列是不能互换的</div><div class="t m0 x8c h5 ya3 ff2 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 x4 h3 ya4 ff4 fs0 fc0 sc0 ls44 wsa">2.3 USB<span class="_ _16"> </span><span class="ff3 sc1 ls2d ws0">设备</span><span class="ls0 ws0"> </span></div><div class="t m0 xe h5 ya5 ff2 fs1 fc0 sc0 ls4 ws0">USB</div><div class="t m0 x42 h4 ya6 ff3 fs1 fc0 sc0 lsc ws0">设备包括</div><div class="t m0 x8d h5 ya5 ff2 fs1 fc0 sc0 ls3a ws0">Hub</div><div class="t m0 x8e h4 ya6 ff3 fs1 fc0 sc0 ls0 ws0">和功能设备</div><div class="t m0 x62 h4 ya7 ff3 fs1 fc0 sc0 ls0 ws0">而功能设备又可以细分为定位设备<span class="_ _9"> </span><span class="lsc">字符设备</span></div><div class="t m0 x4 h4 ya8 ff3 fs1 fc0 sc0 ls0 ws0">等等</div><div class="t m0 x6 h4 ya9 ff3 fs1 fc0 sc0 ls0 ws0">为了进一步叙述<span class="_"> </span>我们给出端点</div><div class="t m0 x8f h5 yaa ff2 fs1 fc0 sc0 lsf ws0">(endpoint)</div><div class="t m0 x3a h4 ya9 ff3 fs1 fc0 sc0 ls0 ws0">和管道</div><div class="t m0 x90 h5 yaa ff2 fs1 fc0 sc0 ls4b ws0">(pipe)</div><div class="t m0 x91 h4 ya9 ff3 fs1 fc0 sc0 ls0 ws0">的概念</div><div class="t m0 x92 h5 yab ff2 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 x4 h6 y25 ff2 fs2 fc0 sc0 ls29 ws0"> </div><div class="t m0 x4 h6 y26 ff2 fs2 fc0 sc0 ls29 ws0"> </div><div class="t m0 x9 h7 y27 ff3 fs3 fc0 sc0 ls0 ws0">第</div><div class="t m0 xa h8 y28 ff2 fs3 fc0 sc0 ls2a ws3"> 3 </div><div class="t m0 xb h7 y27 ff3 fs3 fc0 sc0 ls0 ws0">页</div><div class="t m0 xc h8 y28 ff2 fs3 fc0 sc0 ls0 ws0"> </div></div><div class="pi" data-data='{"ctm":[1.611639,0.000000,0.000000,1.611639,0.000000,0.000000]}'></div></div>
<div id="pf4" class="pf w0 h0" data-page-no="4"><div class="pc pc4 w0 h0"><img class="bi x0 y0 w1 h1" alt="" src="https://static.pudn.com/prod/directory_preview_static/633bb3d72aaf6043c9e80983/bg4.jpg"><div class="t m0 x1 h2 y1 ff1 fs0 fc0 sc0 ls0 ws0">清华大学毕业设计论文<span class="ff2"> </span></div><div class="t m0 xe h4 yac ff3 fs1 fc0 sc1 ls27 ws0">端点</div><div class="t m0 x19 h5 yad ff2 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 x93 h4 yae ff3 fs1 fc0 sc0 ls27 ws0">每一个</div><div class="t m0 x7c h5 yad ff2 fs1 fc0 sc0 lsb ws0">USB</div><div class="t m0 x94 h4 yae ff3 fs1 fc0 sc0 ls4c ws0">设备在主机看来就是一个端点的集合</div><div class="t m0 x95 h4 yac ff3 fs1 fc0 sc0 ls4d ws0">主机只能通过端点</div><div class="t m0 x4 h4 yaf ff3 fs1 fc0 sc0 ls8 ws0">与设备进行通讯<span class="_"> </span><span class="ls4e">以使用设备的功能<span class="_"> </span><span class="ls36">每个端点实际上就是一个一定大小的数据</span></span></div><div class="t m0 x4 h4 yb0 ff3 fs1 fc0 sc0 lsa ws0">缓冲区</div><div class="t m0 x96 h4 yb1 ff3 fs1 fc0 sc0 lsa ws0">这些端点在设备出厂时就已定义好<span class="_"> </span><span class="ls0">在</span></div><div class="t m0 x78 h5 yb2 ff2 fs1 fc0 sc0 ls4 ws0">USB</div><div class="t m0 x36 h4 yb1 ff3 fs1 fc0 sc0 ls4f ws0">系统中<span class="_"> </span><span class="lsa">每一个端点都有唯</span></div><div class="t m0 x4 h4 yb3 ff3 fs1 fc0 sc0 lsd ws0">一的地址<span class="_"> </span><span class="ls36">这是由设备地址和端点号给出的<span class="_"> </span>每个端点都有一定的特性<span class="_"> </span><span class="ls7">其中包</span></span></div><div class="t m0 x4 h4 yb4 ff3 fs1 fc0 sc0 ls0 ws0">括<span class="_ _17"> </span><span class="ls50">传输方式<span class="_"> </span><span class="lsd">总线访问频率<span class="_"> </span><span class="ls3b">带宽<span class="_"> </span><span class="ls7">端点号<span class="_"> </span><span class="ls51">数据包的最大容量等等<span class="_"> </span></span>端点必</span></span></span></span></div><div class="t m0 x4 h4 yb5 ff3 fs1 fc0 sc0 ls0 ws0">须在设备配置后才能生效</div><div class="t m0 x97 h5 yb6 ff2 fs1 fc0 sc0 ls0 ws0">(</div><div class="t m0 x98 h4 yb5 ff3 fs1 fc0 sc0 ls0 ws0">端点</div><div class="t m0 x99 h5 yb6 ff2 fs1 fc0 sc0 ls0 ws0">0</div><div class="t m0 x9a h4 yb5 ff3 fs1 fc0 sc0 ls0 ws0">除外</div><div class="t m0 x1b h5 yb6 ff2 fs1 fc0 sc0 ls0 ws0">)</div><div class="t m0 x2d h5 yb7 ff2 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 x3 h4 yb8 ff3 fs1 fc0 sc0 ls27 ws0">端点</div><div class="t m0 x4b h5 yb9 ff2 fs1 fc0 sc0 ls0 ws0">0</div><div class="t m0 x9b h4 yb8 ff3 fs1 fc0 sc0 ls27 ws0">通常为控制端点</div><div class="t m0 x9c h4 yba ff3 fs1 fc0 sc0 ls27 ws0">用于设备初始化参数等<span class="_"> </span>端点</div><div class="t m0 x7e h5 ybb ff2 fs1 fc0 sc0 ls0 ws0">1</div><div class="t m0 x6b h5 yb9 ff2 fs1 fc0 sc0 ls0 ws0">2</div><div class="t m0 x95 h4 yb8 ff3 fs1 fc0 sc0 ls27 ws0">等一般用作数据端</div><div class="t m0 x4 h4 ybc ff3 fs1 fc0 sc0 ls0 ws0">点</div><div class="t m0 x23 h4 ybd ff3 fs1 fc0 sc0 ls0 ws0">存放主机与设备间往来的数据</div><div class="t m0 x5d h5 ybe ff2 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 xe h4 ybf ff3 fs1 fc0 sc1 ls27 ws0">管道</div><div class="t m0 x19 h5 yc0 ff2 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 x93 h4 yc1 ff3 fs1 fc0 sc0 ls27 ws0">一个</div><div class="t m0 x9d h5 yc0 ff2 fs1 fc0 sc0 lsb ws0">USB</div><div class="t m0 x9e h4 yc1 ff3 fs1 fc0 sc0 ls4c ws0">管道是驱动程序的一个数据缓冲区与一个外设端点的连接</div><div class="t m0 x4 h4 yc2 ff3 fs1 fc0 sc0 lsd ws0">它代表了一种在两者之间移动数据的能力<span class="_"> </span><span class="ls7">一旦设备被配置<span class="_"> </span></span>管道就存在了<span class="_"> </span><span class="ls0">管</span></div><div class="t m0 x4 h4 yc3 ff3 fs1 fc0 sc0 lsa ws0">道有两种类型<span class="_"> </span>数据流管道<span class="_"> </span>其中的数据没有</div><div class="t m0 x77 h5 yc4 ff2 fs1 fc0 sc0 ls4 ws0">USB</div><div class="t m0 x9f h4 yc3 ff3 fs1 fc0 sc0 ls52 ws0">定义的结构<span class="_"> </span><span class="lsa">与消息管道<span class="_"> </span><span class="ls0">其</span></span></div><div class="t m0 x4 h4 yc5 ff3 fs1 fc0 sc0 ls0 ws0">中的数据必须有</div><div class="t m0 xa0 h5 yc6 ff2 fs1 fc0 sc0 ls4 ws0">USB</div><div class="t m0 x8 h4 yc5 ff3 fs1 fc0 sc0 ls0 ws0">定义的结构</div><div class="t m0 xa1 h4 yc7 ff3 fs1 fc0 sc0 ls0 ws0">管道只是一个逻辑上的概念</div><div class="t m0 xa2 h5 yc8 ff2 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 xe h4 yc9 ff3 fs1 fc0 sc0 ls1a ws0">所有的设备必须支持端点</div><div class="t m0 xa3 h5 yca ff2 fs1 fc0 sc0 ls0 ws0">0</div><div class="t m0 x14 h4 yc9 ff3 fs1 fc0 sc0 ls1a ws0">以作为设备的控制管道</div><div class="t m0 xa4 h4 ycb ff3 fs1 fc0 sc0 ls53 ws0">通过控制管道可以获取完</div><div class="t m0 x4 h4 ycc ff3 fs1 fc0 sc0 lsa ws0">全描述</div><div class="t m0 x6 h5 ycd ff2 fs1 fc0 sc0 ls4 ws0">USB</div><div class="t m0 xa5 h4 ycc ff3 fs1 fc0 sc0 lsa ws0">设备的信息<span class="_"> </span>包括<span class="_"> </span>设备类型<span class="_"> </span>电源管理<span class="_"> </span>配置<span class="_"> </span>端点描述等等<span class="_"> </span><span class="ls0">只</span></div><div class="t m0 x4 h4 yce ff3 fs1 fc0 sc0 ls0 ws0">要设备连接到</div><div class="t m0 x7b h5 ycf ff2 fs1 fc0 sc0 ls4 ws0">USB</div><div class="t m0 x3b h4 yce ff3 fs1 fc0 sc0 ls1a ws0">上并且上电<span class="_"> </span><span class="ls0">端点</span></div><div class="t m0 x5d h5 ycf ff2 fs1 fc0 sc0 ls0 ws0">0</div><div class="t m0 x5a h4 yce ff3 fs1 fc0 sc0 ls0 ws0">就可以被访问<span class="_"> </span>与之对应的控制管道就存在</div><div class="t m0 x4 h4 yd0 ff3 fs1 fc0 sc0 ls0 ws0">了</div><div class="t m0 x23 h5 yd1 ff2 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 xe h4 yd2 ff3 fs1 fc0 sc0 ls0 ws0">一个</div><div class="t m0 x42 h5 yd3 ff2 fs1 fc0 sc0 ls4 ws0">USB</div><div class="t m0 xa6 h4 yd2 ff3 fs1 fc0 sc0 ls28 ws0">设备可以分为三个层</div><div class="t m0 xa7 h4 yd4 ff3 fs1 fc0 sc0 ls0 ws0">图</div><div class="t m0 xa8 h5 yd5 ff2 fs1 fc0 sc0 ls0 ws0">2.3</div><div class="t m0 x55 h4 yd4 ff3 fs1 fc0 sc0 ls0 ws0">最底层是总线接口<span class="_ _9"> </span>用来发送与接收</div><div class="t m0 x4 h4 yd6 ff3 fs1 fc0 sc0 ls0 ws0">包</div><div class="t m0 x23 h4 yd7 ff3 fs1 fc0 sc0 ls54 ws0">中间层处理总线接口与不<span class="ls6">同的端点之间的数据流通<span class="_"> </span><span class="ls35">一个端点是数据最终的</span></span></div><div class="t m0 x4 h4 yd8 ff3 fs1 fc0 sc0 lsa ws0">使用者或提供者<span class="_"> </span>它可以看作数据的源或接收端<span class="_"> </span>最上层就是</div><div class="t m0 x95 h5 yd9 ff2 fs1 fc0 sc0 ls4 ws0">USB</div><div class="t m0 x89 h4 yd8 ff3 fs1 fc0 sc0 ls55 ws0">设备所提供的</div><div class="t m0 x4 h4 yda ff3 fs1 fc0 sc0 ls0 ws0">功能<span class="_"> </span>比如鼠标或键盘等</div><div class="t m0 x3e h5 ydb ff2 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 xa9 h12 ydc ff8 fsb fc0 sc0 ls56 wsd">USB<span class="_ _7"></span> Logical</div><div class="t m0 xaa h12 ydd ff8 fsb fc0 sc0 ls57 ws0">Dev<span class="_ _c"></span>i<span class="_ _c"></span>ce</div><div class="t m0 xab h12 yde ff8 fsb fc0 sc0 ls58 ws0">Function</div><div class="t m0 xac h12 ydf ff8 fsb fc0 sc0 ls59 wse">P<span class="_ _7"></span>h<span class="_ _7"></span>ys<span class="_ _7"></span>ic<span class="_ _7"></span>a<span class="_ _7"></span>l<span class="_ _7"></span> D<span class="_ _7"></span>e<span class="_ _7"></span>vi<span class="_ _7"></span>c<span class="_ _7"></span>e</div><div class="t m0 xab h12 ye0 ff8 fsb fc0 sc0 ls57 wsf">USB Bu<span class="_ _c"></span>s</div><div class="t m0 xab h12 ye1 ff8 fsb fc0 sc0 ls5a ws0">Inter<span class="_ _c"></span>face</div><div class="t m0 xad h12 ye2 ff8 fsb fc0 sc0 ls5b ws10">Actual communi<span class="_ _c"></span>cations <span class="_ _c"></span>flow</div><div class="t m0 xa8 h13 ye3 ff3 fsb fc0 sc1 ls5c ws0">实际数据流</div><div class="t m0 xad h12 ye4 ff8 fsb fc0 sc0 ls5d ws11">Logical c<span class="_ _7"></span>ommunic<span class="_ _7"></span>ations flow</div><div class="t m0 xa8 h13 ye5 ff3 fsb fc0 sc1 ls5c ws0">逻辑数据流</div><div class="t m0 xae h5 ye6 ff2 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 x34 h4 ye7 ff3 fs1 fc0 sc0 ls0 ws0">图</div><div class="t m0 xf h5 ye8 ff2 fs1 fc0 sc0 ls3 ws9">2.3 USB</div><div class="t m0 xaf h4 ye7 ff3 fs1 fc0 sc0 ls0 ws0">设备结构层次</div><div class="t m0 xb0 h5 ye8 ff2 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 x4 h6 y25 ff2 fs2 fc0 sc0 ls29 ws0"> </div><div class="t m0 x4 h6 y26 ff2 fs2 fc0 sc0 ls29 ws0"> </div><div class="t m0 x9 h7 y27 ff3 fs3 fc0 sc0 ls0 ws0">第</div><div class="t m0 xa h8 y28 ff2 fs3 fc0 sc0 ls2a ws3"> 4 </div><div class="t m0 xb h7 y27 ff3 fs3 fc0 sc0 ls0 ws0">页</div><div class="t m0 xc h8 y28 ff2 fs3 fc0 sc0 ls0 ws0"> </div></div><div class="pi" data-data='{"ctm":[1.611639,0.000000,0.000000,1.611639,0.000000,0.000000]}'></div></div>
<div id="pf5" class="pf w0 h0" data-page-no="5"><div class="pc pc5 w0 h0"><img class="bi x0 y0 w1 h1" alt="" src="https://static.pudn.com/prod/directory_preview_static/633bb3d72aaf6043c9e80983/bg5.jpg"><div class="t m0 x1 h2 y1 ff1 fs0 fc0 sc0 ls0 ws0">清华大学毕业设计论文<span class="ff2"> </span></div><div class="t m0 x4 h14 ye9 ff4 fsc fc0 sc0 ls5e ws12">2.3.1 Hub </div><div class="t m0 xe h5 yea ff2 fs1 fc0 sc0 ls3a ws0">Hub</div><div class="t m0 xb1 h4 yeb ff3 fs1 fc0 sc0 ls0 ws0">在</div><div class="t m0 xb2 h5 yea ff2 fs1 fc0 sc0 ls4 ws0">USB</div><div class="t m0 xb3 h4 yeb ff3 fs1 fc0 sc0 ls0 ws0">结构中是一个关键</div><div class="t m0 x62 h4 yec ff3 fs1 fc0 sc0 ls0 ws0">它提供了附加的</div><div class="t m0 x57 h5 yed ff2 fs1 fc0 sc0 ls4 ws0">USB</div><div class="t m0 xa4 h4 yec ff3 fs1 fc0 sc0 ls0 ws0">节点<span class="_ _12"> </span>这些节点被称为端</div><div class="t m0 x4 h4 yee ff3 fs1 fc0 sc0 ls0 ws0">口</div><div class="t m0 xe h5 yef ff2 fs1 fc0 sc0 ls3a ws0">Hub</div><div class="t m0 xb1 h4 yf0 ff3 fs1 fc0 sc0 ls0 ws0">可以检测出每一个下行端口的状态</div><div class="t m0 x55 h4 yee ff3 fs1 fc0 sc0 ls0 ws0">并且可以给下端的设备提供电源<span class="_ _15"> </span>图</div><div class="t m0 x4 h5 yf1 ff2 fs1 fc0 sc0 ls0 ws0">2.4</div><div class="t m0 xb4 h4 yf2 ff3 fs1 fc0 sc0 ls0 ws0">是一个典型的</div><div class="t m0 x76 h5 yf1 ff2 fs1 fc0 sc0 ls3a ws0">Hub</div><div class="t m0 xb5 h5 yf3 ff2 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 xe h5 yf4 ff2 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 x57 h15 yf5 ff8 fsd fc0 sc0 ls5f ws0">HUB</div><div class="t m0 xb6 h16 yf6 ff8 fse fc0 sc0 ls31 ws0">Upstream</div><div class="t m0 xb6 h16 yf7 ff8 fse fc0 sc0 ls0 ws0">Port</div><div class="t m0 x77 h16 yf8 ff8 fse fc0 sc0 ls0 ws0">Port</div><div class="t m0 xa9 h16 yf9 ff8 fse fc0 sc0 ls60 ws0">#1</div><div class="t m0 x77 h16 yfa ff8 fse fc0 sc0 ls0 ws0">Port</div><div class="t m0 xb7 h16 yfb ff8 fse fc0 sc0 ls61 ws0">#7</div><div class="t m0 x43 h16 yfa ff8 fse fc0 sc0 ls0 ws0">Port</div><div class="t m0 x3c h16 yfb ff8 fse fc0 sc0 ls61 ws0">#6</div><div class="t m0 x59 h16 yfc ff8 fse fc0 sc0 ls0 ws0">Port</div><div class="t m0 x2f h16 yfd ff8 fse fc0 sc0 ls61 ws0">#5</div><div class="t m0 x68 h16 yfe ff8 fse fc0 sc0 ls0 ws0">Port</div><div class="t m0 x95 h16 yff ff8 fse fc0 sc0 ls60 ws0">#4</div><div class="t m0 x36 h16 y100 ff8 fse fc0 sc0 ls0 ws0">Port</div><div class="t m0 x3c h16 y101 ff8 fse fc0 sc0 ls61 ws0">#2</div><div class="t m0 x44 h16 y102 ff8 fse fc0 sc0 ls0 ws0">Port</div><div class="t m0 x2f h16 y103 ff8 fse fc0 sc0 ls61 ws0">#3</div><div class="t m0 xb8 h5 y104 ff2 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 xe h5 y105 ff2 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 x94 h4 y106 ff3 fs1 fc0 sc0 ls0 ws0">图</div><div class="t m0 x63 h5 y107 ff2 fs1 fc0 sc0 ls0 ws0">2.4 </div><div class="t m0 xb9 h4 y106 ff3 fs1 fc0 sc0 ls0 ws0">典型的</div><div class="t m0 x6a h5 y107 ff2 fs1 fc0 sc0 ls4 ws0">USB</div><div class="t m0 xba h4 y106 ff3 fs1 fc0 sc0 ls0 ws0">集线器</div><div class="t m0 x81 h5 y107 ff2 fs1 fc0 sc0 ls3a ws0">Hub<span class="_ _3"> </span><span class="ls0"> </span></div><div class="t m0 x4 h14 y108 ff4 fsc fc0 sc0 ls62 ws0">2.3.2 <span class="_ _18"> </span><span class="ff3 sc1 ls3b">即插即用</span><span class="ls0"> </span></div><div class="t m0 xe h5 y109 ff2 fs1 fc0 sc0 ls4 ws0">USB</div><div class="t m0 x42 h4 y10a ff3 fs1 fc0 sc0 ls28 ws0">设备可以即插即用</div><div class="t m0 xbb h4 y10b ff3 fs1 fc0 sc0 ls0 ws0">但在可以使用之前<span class="_ _10"> </span>必须对设备进行配置<span class="_ _10"> </span>一旦设备</div><div class="t m0 x4 h4 y10c ff3 fs1 fc0 sc0 ls0 ws0">连接到某一个</div><div class="t m0 x7b h5 y10d ff2 fs1 fc0 sc0 ls4 ws0">USB</div><div class="t m0 x3b h4 y10c ff3 fs1 fc0 sc0 ls18 ws0">的节点上</div><div class="t m0 xa3 h5 y10e ff2 fs1 fc0 sc0 ls4 ws0">USB</div><div class="t m0 xbc h4 y10f ff3 fs1 fc0 sc0 ls0 ws0">就会产生一系列的操作</div><div class="t m0 xbd h4 y10c ff3 fs1 fc0 sc0 ls0 ws0">来完成对设备的配置</div><div class="t m0 x4 h4 y110 ff3 fs1 fc0 sc0 ls0 ws0">这种操作被称为总线枚举过程</div><div class="t m0 xbe h5 y111 ff2 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 xe h5 y112 ff2 fs1 fc0 sc0 ls0 ws0">1.</div><div class="t m0 x80 h4 y113 ff3 fs1 fc0 sc0 ls0 ws0">设备所连接的</div><div class="t m0 xbf h5 y112 ff2 fs1 fc0 sc0 ls3a ws0">Hub</div><div class="t m0 x7d h4 y113 ff3 fs1 fc0 sc0 ls0 ws0">检测出端口上有设备连接<span class="_ _19"> </span>通过状态变化管道向主机报告</div><div class="t m0 x53 h5 y112 ff2 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 xe h5 y114 ff2 fs1 fc0 sc0 ls0 ws0">2.</div><div class="t m0 x80 h4 y115 ff3 fs1 fc0 sc0 ls0 ws0">主机通过询问</div><div class="t m0 xbf h5 y114 ff2 fs1 fc0 sc0 ls3a ws0">Hub</div><div class="t m0 x7d h4 y115 ff3 fs1 fc0 sc0 ls0 ws0">以获取确切的信息</div><div class="t m0 x1e h5 y114 ff2 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 xe h5 y116 ff2 fs1 fc0 sc0 ls0 ws0">3.</div><div class="t m0 x80 h4 y117 ff3 fs1 fc0 sc0 ls0 ws0">主机这时知道设备连接到哪个端口上</div><div class="t m0 x4d h4 y118 ff3 fs1 fc0 sc0 ls0 ws0">于是向这个端口发出复位命令</div><div class="t m0 x83 h5 y116 ff2 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 xe h5 y119 ff2 fs1 fc0 sc0 ls31 ws0">4.Hub</div><div class="t m0 xc0 h4 y11a ff3 fs1 fc0 sc0 ls63 ws0">发出的复位信号结束后<span class="_"> </span><span class="ls7">端口被打开</span></div><div class="t m0 x4e h5 y11b ff2 fs1 fc0 sc0 ls3a ws0">Hub</div><div class="t m0 x1f h4 y11c ff3 fs1 fc0 sc0 ls7 ws0">向设备提供</div><div class="t m0 x45 h5 y11b ff2 fs1 fc0 sc0 ls32 ws0">100mA</div><div class="t m0 xc1 h4 y11c ff3 fs1 fc0 sc0 ls7 ws0">的电源</div><div class="t m0 x4 h4 y11d ff3 fs1 fc0 sc0 ls0 ws0">这时设备上电<span class="_"> </span>所有的寄存器复位<span class="_"> </span>并且以缺省地址</div><div class="t m0 xc2 h5 y11e ff2 fs1 fc0 sc0 ls0 ws0">0</div><div class="t m0 xc3 h4 y11d ff3 fs1 fc0 sc0 ls0 ws0">以及端点</div><div class="t m0 x4a h5 y11e ff2 fs1 fc0 sc0 ls0 ws0">0</div><div class="t m0 x82 h4 y11d ff3 fs1 fc0 sc0 ls0 ws0">响应命令</div><div class="t m0 xc4 h5 y11f ff2 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 xe h5 y120 ff2 fs1 fc0 sc0 ls0 ws0">5.</div><div class="t m0 x80 h4 y121 ff3 fs1 fc0 sc0 ls64 ws0">主机通过缺省地址与端点</div><div class="t m0 xc5 h5 y120 ff2 fs1 fc0 sc0 ls0 ws0">0</div><div class="t m0 xc6 h4 y121 ff3 fs1 fc0 sc0 ls65 ws0">进行通讯</div><div class="t m0 x1e h4 y122 ff3 fs1 fc0 sc0 ls64 ws0">赋予设备一个独一的地址<span class="_"> </span><span class="ls3b">并且读取</span></div><div class="t m0 x4 h4 y123 ff3 fs1 fc0 sc0 ls0 ws0">设备的配置信息</div><div class="t m0 x39 h5 y124 ff2 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 xe h5 y125 ff2 fs1 fc0 sc0 ls0 ws0">6.</div><div class="t m0 x80 h4 y126 ff3 fs1 fc0 sc0 ls0 ws0">最后主机对设备进行配置</div><div class="t m0 xb9 h5 y125 ff2 fs1 fc0 sc0 ls0 ws0">,</div><div class="t m0 xf h4 y126 ff3 fs1 fc0 sc0 ls0 ws0">该设备就可以使用了</div><div class="t m0 x86 h5 y125 ff2 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 xe h4 y127 ff3 fs1 fc0 sc0 ls0 ws0">当该设备被移走时</div><div class="t m0 xc7 h5 y128 ff2 fs1 fc0 sc0 ls3a ws0">Hub</div><div class="t m0 xc8 h4 y127 ff3 fs1 fc0 sc0 ls0 ws0">依然要报告主机</div><div class="t m0 xc9 h4 y129 ff3 fs1 fc0 sc0 ls0 ws0">并且关闭端口<span class="_ _9"> </span>一旦主机接到设备</div><div class="t m0 x4 h4 y12a ff3 fs1 fc0 sc0 ls0 ws0">移走的报告</div><div class="t m0 x7b h4 y12b ff3 fs1 fc0 sc0 ls0 ws0">就会改写当前结构信息</div><div class="t m0 x8f h5 y12c ff2 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 x4 h6 y25 ff2 fs2 fc0 sc0 ls29 ws0"> </div><div class="t m0 x4 h6 y26 ff2 fs2 fc0 sc0 ls29 ws0"> </div><div class="t m0 x9 h7 y27 ff3 fs3 fc0 sc0 ls0 ws0">第</div><div class="t m0 xa h8 y28 ff2 fs3 fc0 sc0 ls2a ws3"> 5 </div><div class="t m0 xb h7 y27 ff3 fs3 fc0 sc0 ls0 ws0">页</div><div class="t m0 xc h8 y28 ff2 fs3 fc0 sc0 ls0 ws0"> </div></div><div class="pi" data-data='{"ctm":[1.611639,0.000000,0.000000,1.611639,0.000000,0.000000]}'></div></div>
Vander 2011-05-01 09:38:46不能下载啊。