实例——usb设备驱动设计（上）--山野村夫.htm

USB驱动设计的步骤和主要程序框架

                              lang=EN-US>DMA</SPAN><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">传输。</SPAN></P>
                              <P class=MsoNormal 
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                              lang=EN-US><o:p>&nbsp;</o:p></SPAN></P>
                              <P class=MsoNormal 
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                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">它的功能结构如图</SPAN><SPAN 
                              lang=EN-US>7-7</SPAN><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">所示。</SPAN></P><BR></DIV>
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                              <DIV>
                              <P class=MsoNormal 
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                              lang=EN-US>3</SPAN><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">．</SPAN><SPAN 
                              lang=EN-US>USB</SPAN><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">端口模式</SPAN></P>
                              <P class=MsoNormal 
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                              lang=EN-US><o:p>&nbsp;</o:p></SPAN></P>
                              <P class=MsoNormal 
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                              lang=EN-US><SPAN style="mso-spacerun: yes">&nbsp; 
                              </SPAN>USB</SPAN><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">控制器的端口适用于不同类型的设备，例如：图像、打印机、海量存储器和通信设备。端口可通过“</SPAN><SPAN 
                              lang=EN-US>Set Mode</SPAN><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">”命令配置为</SPAN><SPAN 
                              lang=EN-US>4</SPAN><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">种不同的模式，对应表</SPAN><SPAN 
                              lang=EN-US>7-2</SPAN><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">～表</SPAN><SPAN 
                              lang=EN-US>7-5</SPAN><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">所示。</SPAN></P>
                              <P class=MsoNormal 
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                              lang=EN-US><o:p>&nbsp;</o:p></SPAN></P>
                              <P class=MsoNormal 
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                              lang=EN-US><SPAN style="mso-spacerun: yes">&nbsp; 
                              </SPAN></SPAN><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">·模式</SPAN><SPAN 
                              lang=EN-US>O(non-ISO</SPAN><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">模式</SPAN><SPAN 
                              lang=EN-US>)</SPAN><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">：非同步传输；</SPAN></P>
                              <P class=MsoNormal 
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                              lang=EN-US><o:p>&nbsp;</o:p></SPAN></P>
                              <P class=MsoNormal 
                              style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21pt; mso-char-indent-count: 2.0"><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">·模式</SPAN><SPAN 
                              lang=EN-US>1(ISO-OUT</SPAN><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">模式</SPAN><SPAN 
                              lang=EN-US>)</SPAN><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">：同步输出模式；</SPAN></P>
                              <P class=MsoNormal 
                              style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21pt; mso-char-indent-count: 2.0"><SPAN 
                              lang=EN-US><o:p>&nbsp;</o:p></SPAN></P>
                              <P class=MsoNormal 
                              style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21pt; mso-char-indent-count: 2.0"><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">·模式</SPAN><SPAN 
                              lang=EN-US>2(ISO-IN</SPAN><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">模式</SPAN><SPAN 
                              lang=EN-US>)</SPAN><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">：同步输入模式；</SPAN></P>
                              <P class=MsoNormal 
                              style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21pt; mso-char-indent-count: 2.0"><SPAN 
                              lang=EN-US><o:p>&nbsp;</o:p></SPAN></P>
                              <P class=MsoNormal 
                              style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21pt; mso-char-indent-count: 2.0"><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">·模式</SPAN><SPAN 
                              lang=EN-US>3(ISO-IO</SPAN><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">模式</SPAN><SPAN 
                              lang=EN-US>)</SPAN><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">：同步输入输出传输。</SPAN></P><BR></DIV>
                              <DIV><IMG onmousewheel="return bbimg(this)" 
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                              <DIV>
                              <P class=MsoNormal 
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                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">这些端点描述符分别定义如下：</SPAN></P><BR></DIV>
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                              <DIV>
                              <P class=MsoNormal 
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                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">其中主端口</SPAN><SPAN 
                              lang=EN-US>(</SPAN><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">端口</SPAN><SPAN 
                              lang=EN-US>2)</SPAN><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">在有些方面是比较特别的，它是吞吐大数据的主要端口。同时，它执行主端口的特性以减轻传输大数据的任务。</SPAN></P>
                              <P class=MsoNormal 
                              style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt"><SPAN 
                              lang=EN-US><o:p>&nbsp;</o:p></SPAN></P>
                              <P class=MsoNormal 
                              style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt"><SPAN 
                              lang=EN-US>(1)</SPAN><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">双缓冲：允许</SPAN><SPAN 
                              lang=EN-US>USB</SPAN><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">与</SPAN><SPAN 
                              lang=EN-US>ARM</SPAN><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">之间进行并行读写操作，这样就增加了数据的吞吐量。缓冲区切换是自动处理的，这导致了透明的缓冲区操作。</SPAN></P>
                              <P class=MsoNormal 
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                              lang=EN-US><o:p>&nbsp;</o:p></SPAN></P>
                              <P class=MsoNormal 
                              style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt"><SPAN 
                              lang=EN-US>(2)</SPAN><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">支持</SPAN><SPAN 
                              lang=EN-US>DMA(</SPAN><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">直接存储器访问</SPAN><SPAN 
                              lang=EN-US>)</SPAN><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">操作：可以与其他端点的正常</SPAN><SPAN 
                              lang=EN-US>I</SPAN><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">／</SPAN><SPAN 
                              lang=EN-US>O</SPAN><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">操作交叉进行。</SPAN></P>
                              <P class=MsoNormal 
                              style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt"><SPAN 
                              lang=EN-US><o:p>&nbsp;</o:p></SPAN></P>
                              <P class=MsoNormal 
                              style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt"><SPAN 
                              lang=EN-US>(3)DMA</SPAN><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">操作中的自动指针处理：在跨过缓冲区边界时不需要</SPAN><SPAN 
                              lang=EN-US>ARM</SPAN><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">的干预。</SPAN></P>
                              <P class=MsoNormal 
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                              lang=EN-US><o:p>&nbsp;</o:p></SPAN></P>
                              <P class=MsoNormal 
                              style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt"><SPAN 
                              lang=EN-US>(4)</SPAN><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">可配置为同步传输或非同步</SPAN><SPAN 
                              lang=EN-US>(</SPAN><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">批量和中断</SPAN><SPAN 
                              lang=EN-US>)</SPAN><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">传输。</SPAN></P>
                              <P class=MsoNormal 
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                              lang=EN-US><o:p>&nbsp;</o:p></SPAN></P>
                              <P class=MsoNormal 
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                              lang=EN-US>4</SPAN><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">．系统硬件电路结构图</SPAN></P>
                              <P class=MsoNormal 
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                              lang=EN-US><o:p>&nbsp;</o:p></SPAN></P>
                              <P class=MsoNormal 
                              style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt"><SPAN 
                              lang=EN-US>USB</SPAN><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">接口主芯片电路如图</SPAN><SPAN 
                              lang=EN-US>7-8</SPAN><SPAN 
                              style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">所