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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/626944d54f8811599e1ddd6e/bg1.jpg"><div class="t m0 x1 h2 y1 ff1 fs0 fc0 sc0 ls0 ws0">应用指南</div><div class="t m0 x1 h3 y2 ff2 fs1 fc0 sc0 ls0 ws0">T<span class="_ _0"></span>ime-to-Digital-Converter</div><div class="t m0 x1 h4 y3 ff1 fs2 fc1 sc0 ls0 ws0">时间数字转换器<span class="ff3">TDC-GP21</span>的</div><div class="t m0 x1 h4 y4 ff1 fs2 fc1 sc0 ls0 ws0">超声波热量表应用 </div><div class="t m0 x1 h5 y5 ff1 fs3 fc1 sc0 ls0 ws0"> 2011年10月19日</div><div class="t m0 x1 h5 y6 ff1 fs3 fc1 sc0 ls0 ws0">版本-No.: AN029_cn V1.1 </div></div><div class="pi" data-data='{"ctm":[1.612697,0.000000,0.000000,1.612697,0.000000,0.000000]}'></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/626944d54f8811599e1ddd6e/bg2.jpg"><div class="t m0 x2 h6 y7 ff4 fs4 fc1 sc0 ls0 ws0">acam-messelectronic gmbh - Am Hasenbiel 27 - D-76297 Stutensee-Blankenloch - Germany - www<span class="_ _1"></span>.acam.de</div><div class="t m0 x3 h2 y8 ff1 fs0 fc1 sc0 ls0 ws0">时间数字转换器</div><div class="t m0 x4 h6 y9 ff4 fs4 fc1 sc0 ls0 ws0">2</div><div class="t m0 x5 h7 ya ff4 fs5 fc1 sc0 ls0 ws0">TDC-GP21</div><div class="t m0 x3 h8 yb ff5 fs6 fc1 sc0 ls0 ws0">概述 </div><div class="t m0 x3 h9 yc ff5 fs7 fc1 sc0 ls0 ws0">在2010年9月，acam公司发布了时间数字转换器最新一代产品TDC-GP21。这颗芯片集成了非常强</div><div class="t m0 x3 h9 yd ff5 fs7 fc1 sc0 ls0 ws0">大的时用于超声波流量热量计量所需的功能，使设计者可以非常方便实现对于ps级别的时间测量</div><div class="t m0 x3 h9 ye ff5 fs7 fc1 sc0 ls0 ws0">开发。</div><div class="t m0 x3 h9 yf ff5 fs7 fc1 sc0 ls0 ws0"> </div><div class="t m0 x3 h9 y10 ff5 fs7 fc1 sc0 ls0 ws0">尤其芯片内部所集成的斩波稳定比较器和模拟开关，大大的简化了超声波热量表的硬件设计，使</div><div class="t m0 x3 h9 y11 ff5 fs7 fc1 sc0 ls0 ws0">整个设计的外部元器件降到最低。 </div><div class="t m0 x3 h9 y12 ff5 fs7 fc1 sc0 ls0 ws0">这个应用指南作为TDC-GP21的一个额外的功能描述文档，主要介绍了TDC-GP21在超声波热量表应</div><div class="t m0 x3 h9 y13 ff5 fs7 fc1 sc0 ls0 ws0">用中的一些特殊设计和功能。它提供了额外的一些参考信息帮助降低开发的时间，而且可以避免</div><div class="t m0 x3 h9 y14 ff5 fs7 fc1 sc0 ls0 ws0">一些错误的电路设计，错误的元器件使用，以及错误的寄存器配置。另外，它还包含了PCB的布</div><div class="t m0 x3 h9 y15 ff5 fs7 fc1 sc0 ls0 ws0">线指导，以及完整的演示版电路，避免了电路故障以及其它一些设计问题。最终，应用指南包含</div><div class="t m0 x3 h9 y16 ff5 fs7 fc1 sc0 ls0 ws0">了一个样例代码，实现典型的芯片超声波测量功能。</div><div class="t m0 x3 h9 y17 ff5 fs7 fc1 sc0 ls0 ws0">请注意，这些所提供的信息是准确和可靠的。尽管如此，acam公司并不承担所提供信息准确性的</div><div class="t m0 x3 h9 y18 ff5 fs7 fc1 sc0 ls0 ws0">责任，也不回承担由于任何第三方或者其它专利所引起的责任。acam公司将不会对这里所提供的</div><div class="t m0 x3 h9 y19 ff5 fs7 fc1 sc0 ls0 ws0">信息做任何担保。</div><div class="t m0 x6 ha y1a ff4 fs7 fc1 sc0 ls0 ws0">Author: Klaus W<span class="_ _1"></span>eser</div></div><div class="pi" data-data='{"ctm":[1.612697,0.000000,0.000000,1.612697,0.000000,0.000000]}'></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/626944d54f8811599e1ddd6e/bg3.jpg"><div class="t m0 x2 h6 y9 ff4 fs4 fc1 sc0 ls0 ws0">acam-messelectronic gmbh - Am Hasenbiel 27 - D-76297 Stutensee-Blankenloch - Germany - www<span class="_ _1"></span>.acam.de<span class="_ _2"> </span>3</div><div class="t m0 x7 hb y1b ff1 fs6 fc1 sc0 ls0 ws0">目录</div><div class="t m0 x7 h7 y1c ff4 fs5 fc1 sc0 ls0 ws0">TDC-GP21</div><div class="t m0 x7 hb y1d ff2 fs6 fc1 sc0 ls0 ws0">1<span class="ff1"> <span class="_ _3"> </span>介绍 <span class="_ _4"></span>...............................................<span class="_ _5"> </span><span class="ff6">4</span></span></div><div class="t m0 x7 hc y1e ff1 fs7 fc1 sc0 ls0 ws0">1.1 <span class="_ _6"> </span>流量测量 <span class="_ _7"></span>......................................................................<span class="ff6">5</span></div><div class="t m0 x7 hc y1f ff1 fs7 fc1 sc0 ls0 ws0">1.2 <span class="_ _6"> </span>温度差测量 <span class="_ _7"></span>....................................................................<span class="ff6">7</span></div><div class="t m0 x7 hb y20 ff1 fs6 fc1 sc0 ls0 ws0">2 <span class="_ _8"> </span>电路描述 <span class="_ _4"></span>...........................................<span class="_ _5"> </span><span class="ff6">8</span></div><div class="t m0 x7 hc y21 ff1 fs7 fc1 sc0 ls0 ws0">2.1 <span class="_ _6"> </span>电源设计考虑 <span class="_ _7"></span>..................................................................<span class="ff6">8</span></div><div class="t m0 x7 hc y22 ff1 fs7 fc1 sc0 ls0 ws0">2.2 <span class="_ _6"> </span>外部时钟源 <span class="_ _7"></span>....................................................................9</div><div class="t m0 x7 hc y23 ff1 fs7 fc1 sc0 ls0 ws0">2.2.1 <span class="_ _9"> </span>32,768 Hz石英晶振 <span class="_ _a"></span>......................................................9</div><div class="t m0 x7 hc y24 ff1 fs7 fc1 sc0 ls0 ws0">2.2.2 <span class="_ _9"> </span>4 MHz 高速振荡 <span class="_ _a"></span>..........................................................9</div><div class="t m0 x7 hc y25 ff1 fs7 fc1 sc0 ls0 ws0">2.2.3 <span class="_ _9"> </span>外部单片机的时钟选项 <span class="_ _a"></span>...................................................10</div><div class="t m0 x7 hc y26 ff1 fs7 fc1 sc0 ls0 ws0">2.3 <span class="_ _6"> </span>发送/ 接收电路 <span class="_ _7"></span>...............................................................10</div><div class="t m0 x7 hc y27 ff1 fs7 fc1 sc0 ls0 ws0">2.3.1 <span class="_ _9"> </span> Stop 通道的时间窗口设置 <span class="_ _a"></span>...............................................12</div><div class="t m0 x7 hb y28 ff1 fs6 fc1 sc0 ls0 ws0">3 <span class="_ _8"> </span>GP21演示板的Layout & 原理图 <span class="_ _4"></span>.......................<span class="_ _5"> </span>14</div><div class="t m0 x7 hc y29 ff1 fs7 fc1 sc0 ls0 ws0">3.1 <span class="_ _6"> </span>原理图 <span class="_ _7"></span>.......................................................................14</div><div class="t m0 x7 hc y2a ff1 fs7 fc1 sc0 ls0 ws0">3.2 <span class="_ _6"> </span>Layout布线 <span class="_ _7"></span>..................................................................15</div><div class="t m0 x7 hc y2b ff1 fs7 fc1 sc0 ls0 ws0">3.2.1 <span class="_ _9"> </span>顶层 <span class="_ _a"></span>...................................................................15</div><div class="t m0 x7 hc y2c ff1 fs7 fc1 sc0 ls0 ws0">3.2.2 <span class="_ _9"> </span>底层 <span class="_ _a"></span>...................................................................16</div><div class="t m0 x7 hc y2d ff1 fs7 fc1 sc0 ls0 ws0">3.2.3 <span class="_ _9"> </span>元件放置 <span class="_ _a"></span>...............................................................16</div><div class="t m0 x7 hb y2e ff1 fs6 fc1 sc0 ls0 ws0">4 <span class="_ _8"> </span>样例配置 <span class="_ _4"></span>..........................................<span class="_ _5"> </span>17</div><div class="t m0 x7 hb y2f ff1 fs6 fc1 sc0 ls0 ws0">5 <span class="_ _8"> </span> 编写样例 <span class="_ _4"></span>.........................................<span class="_ _5"> </span>19</div><div class="t m0 x7 hb y30 ff1 fs6 fc1 sc0 ls0 ws0">6 <span class="_ _8"> </span>例程代码 <span class="_ _4"></span>..........................................<span class="_ _5"> </span>23</div><div class="t m0 x7 hb y31 ff1 fs6 fc1 sc0 ls0 ws0">7 <span class="_ _8"> </span>文献指导 <span class="_ _4"></span>..........................................<span class="_ _5"> </span>34</div><div class="t m0 x7 hb y32 ff1 fs6 fc1 sc0 ls0 ws0">8 <span class="_ _8"> </span>修订历史 <span class="_ _4"></span>..........................................<span class="_ _5"> </span>34</div></div><div class="pi" data-data='{"ctm":[1.612697,0.000000,0.000000,1.612697,0.000000,0.000000]}'></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/626944d54f8811599e1ddd6e/bg4.jpg"><div class="t m0 x2 h6 y33 ff4 fs4 fc1 sc0 ls0 ws0">acam-messelectronic gmbh - Am Hasenbiel 27 - D-76297 Stutensee-Blankenloch - Germany - www<span class="_ _1"></span>.acam.de</div><div class="t m0 x4 h6 y34 ff4 fs4 fc1 sc0 ls0 ws0">4</div><div class="t m0 x5 h7 y35 ff4 fs5 fc1 sc0 ls0 ws0">TDC-GP21</div><div class="t m0 x1 h4 y36 ff1 fs2 fc1 sc0 ls0 ws0">时间数字转换器</div><div class="t m0 x2 h6 y33 ff4 fs4 fc1 sc0 ls0 ws0">acam-messelectronic gmbh - Am Hasenbiel 27 - D-76297 Stutensee-Blankenloch - Germany - www<span class="_ _1"></span>.acam.de</div><div class="t m0 x4 h6 y34 ff4 fs4 fc1 sc0 ls0 ws0">4</div><div class="t m0 x1 h8 y37 ff5 fs6 fc1 sc0 ls0 ws0">1 <span class="_ _b"> </span>介绍</div><div class="t m0 x1 h9 y38 ff5 fs7 fc1 sc0 ls0 ws0">这个应用指南描述了基于acam公司的时间数字转换器TDC-GP21测量前端的超声波热量表时间测量</div><div class="t m0 x1 h9 y39 ff5 fs7 fc1 sc0 ls0 ws0">方面的应用。GP21作为一个前端测量电路提供了对于流量以及温度的完全自动测量。而热量的计</div><div class="t m0 x1 h9 y3a ff5 fs7 fc1 sc0 ls0 ws0">算则依靠在上游和下游温差以及流体流量通过单片机计算而出。</div><div class="t m0 x1 hd y3b ff5 fs8 fc1 sc0 ls0 ws0">图 1.1: GP21 热量表前端测量电路</div><div class="t m0 x1 h9 y3c ff5 fs7 fc1 sc0 ls0 ws0">设计的目标:</div><div class="t m0 x2 h9 y3d ff5 fs7 fc1 sc0 ls0 ws0"> <span class="_ _c"></span><span class="ff7"><span class="_ _d"> </span><span class="ff5">最少外部元件，非常紧凑和节省成本的硬件设计</span></span></div><div class="t m0 x2 h9 y3e ff5 fs7 fc1 sc0 ls0 ws0"> <span class="_ _c"></span><span class="ff7"><span class="_ _d"> </span><span class="ff5">功耗非常低 (一次测量循环包括模拟部分，换能器以及温度传感器在内最低功耗仅为 2 µA)</span></span></div><div class="t m0 x2 h9 y3f ff5 fs7 fc1 sc0 ls0 ws0"> <span class="_ _c"></span><span class="ff7"><span class="_ _d"> </span><span class="ff5">高精度的飞行时间测量能力可以允许测量管径以及基表的设计设计非常紧凑</span></span></div><div class="t m0 x2 h9 y40 ff5 fs7 fc1 sc0 ls0 ws0"> <span class="_ _c"></span><span class="ff7"><span class="_ _d"> </span><span class="ff5">高精度的温度测量</span></span></div><div class="t m0 x2 h9 y41 ff5 fs7 fc1 sc0 ls0 ws0"> <span class="_ _c"></span><span class="ff7"><span class="_ _d"> </span><span class="ff5">开源的系统结构允许了非常灵活的设计，通过外部单片机进行控制而且允许紧凑的模块化设计</span></span></div></div><div class="pi" data-data='{"ctm":[1.612697,0.000000,0.000000,1.612697,0.000000,0.000000]}'></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/626944d54f8811599e1ddd6e/bg5.jpg"><div class="t m0 x2 h6 y33 ff4 fs4 fc1 sc0 ls0 ws0">acam-messelectronic gmbh - Am Hasenbiel 27 - D-76297 Stutensee-Blankenloch - Germany - www<span class="_ _1"></span>.acam.de<span class="_ _e"> </span>5</div><div class="t m0 x1 h7 y42 ff4 fs5 fc1 sc0 ls0 ws0">TDC-GP21</div><div class="t m0 x2 h6 y33 ff4 fs4 fc1 sc0 ls0 ws0">acam-messelectronic gmbh - Am Hasenbiel 27 - D-76297 Stutensee-Blankenloch - Germany - www<span class="_ _1"></span>.acam.de<span class="_ _e"> </span>5</div><div class="t m0 x1 h9 y43 ff5 fs7 fc1 sc0 ls0 ws0">1.1 <span class="_ _f"> </span>流量测量</div><div class="t m0 x1 h9 y44 ff5 fs7 fc1 sc0 ls0 ws0">超声波流量测量是基于超声波上下游非常时间的。两个超声波换能器将会连接到GP21的两个端</div><div class="t m0 x1 h9 y45 ff5 fs7 fc1 sc0 ls0 ws0">口。这个两个换能器可以作为接受或者发射端. </div><div class="t m0 x4 he y46 ff5 fs4 fc1 sc0 ls0 ws0">图 1.2 基于时间间隔测量的超声波流量测量原理</div><div class="t m0 x1 h9 y47 ff5 fs7 fc1 sc0 ls0 ws0">GP21 可以交替发射出两路驱动换能器的1Mhz脉冲(例如20 个脉冲)，然后测量这个脉冲经由液体</div><div class="t m0 x1 h9 y48 ff5 fs7 fc1 sc0 ls0 ws0">的媒介从换能器a到b的飞行时间，然后反向测量从b到a。 在顺流当中超声波的飞行时间要比在逆</div><div class="t m0 x1 h9 y49 ff5 fs7 fc1 sc0 ls0 ws0">流当中超声波的飞行时间短.</div><div class="t m0 x1 h9 y4a ff5 fs7 fc1 sc0 ls0 ws0">那么如下公式所示，流体的流动速度为v, 而测量管段的路径为 L，在液体当中的声速为C0, 那</div><div class="t m0 x1 h9 y4b ff5 fs7 fc1 sc0 ls0 ws0">么超声波将会有上有传播时间tup， 以及下游传播时间tdown:</div><div class="t m0 x8 h9 y4c ff5 fs7 fc1 sc0 ls0 ws0">[1] </div><div class="t m0 x9 h9 y4d ff5 fs7 fc1 sc0 ls0 ws0"> </div><div class="t m0 x9 h9 y4e ff5 fs7 fc1 sc0 ls0 ws0"> [2]</div></div><div class="pi" data-data='{"ctm":[1.612697,0.000000,0.000000,1.612697,0.000000,0.000000]}'></div></div>
