查看“Micro:bit系列教程17：Liquid Level Sensor”的源代码

<p class="MsoNormal" style="line-height:150%"><span style="font-size:12.0pt;
line-height:150%;font-family:宋体">本章将介绍通过<span lang="EN-US">Liquid Level Sensor (液位传感器)</span>模块进行液位检测。<span lang="EN-US"></span></span></p>
<h1 style="line-height:150%"><span lang="EN-US" style="font-size:15.0pt;
line-height:150%;font-family:黑体;font-weight:normal;mso-bidi-font-weight:bold">1.</span><span style="font-size:15.0pt;line-height:150%;font-family:黑体;font-weight:normal;
mso-bidi-font-weight:bold">基本介绍<span lang="EN-US"></span></span></h1>
<p class="MsoNormal" style="line-height:150%"><span lang="EN-US" style="font-size:
12.0pt;line-height:150%;font-family:宋体"><span style="mso-tab-count:1">  </span>Liquid
level Sensor</span><span style="font-size:12.0pt;line-height:150%;font-family:
宋体">模块利用三极管的电流放大原理，当液位的高度使三极管的基极与电源正极导通的时候，在三极管的基极和发射极之间就会产生一定大小的电流，此时在三极管的集电极和发射极之间就会产生一个一定放大倍数的电流，该电流经过发射极的电阻产生电压供<span lang="EN-US">AD</span>转换器采集。<span lang="EN-US"></span></span></p>
<h1 style="line-height:150%"><span lang="EN-US" style="font-size:15.0pt;
line-height:150%;font-family:黑体;font-weight:normal;mso-bidi-font-weight:bold">2.</span><span style="font-size:15.0pt;line-height:150%;font-family:黑体;font-weight:normal;
mso-bidi-font-weight:bold">硬件连接<span lang="EN-US"></span></span></h1>
<p class="MsoNormal" style="line-height:150%"><span lang="EN-US"><span style="mso-tab-count:1">    </span></span><span style="font-size:12.0pt;
line-height:150%;font-family:宋体">在硬件上，采用<span lang="EN-US">Micro:bit</span>的<span lang="EN-US">P0</span>引脚来采集模拟电压，并进行<span lang="EN-US">AD</span>转换，从而得到数字信号，获取液位相对值。<span lang="EN-US"></span></span></p>
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 mso-yfti-tbllook:1184;mso-padding-alt:0cm 5.4pt 0cm 5.4pt">
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<td style="width:207.4pt;border:solid windowtext 1.0pt;mso-border-alt:
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<p align="center" class="MsoNormal" style="text-align:center;line-height:150%"><span lang="EN-US" style="font-size:12.0pt;line-height:150%;font-family:宋体">Micro:bit</span></p>
</td>
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<p align="center" class="MsoNormal" style="text-align:center;line-height:150%"><span lang="EN-US" style="font-size:12.0pt;line-height:150%;font-family:宋体">Liquid level
  Sensor</span></p>
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<tr style="mso-yfti-irow:1">
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  none;mso-border-top-alt:solid windowtext .5pt;mso-border-alt:solid windowtext .5pt;
  padding:0cm 5.4pt 0cm 5.4pt" width="277">
<p align="center" class="MsoNormal" style="text-align:center;line-height:150%"><span lang="EN-US" style="font-size:12.0pt;line-height:150%;font-family:宋体">VCC</span></p>
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  border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;
  mso-border-top-alt:solid windowtext .5pt;mso-border-left-alt:solid windowtext .5pt;
  mso-border-alt:solid windowtext .5pt;padding:0cm 5.4pt 0cm 5.4pt" width="277">
<p align="center" class="MsoNormal" style="text-align:center;line-height:150%"><span lang="EN-US" style="font-size:12.0pt;line-height:150%;font-family:宋体">VCC</span></p>
</td>
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<tr style="mso-yfti-irow:2">
<td style="width:207.4pt;border:solid windowtext 1.0pt;border-top:
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<p align="center" class="MsoNormal" style="text-align:center;line-height:150%"><span lang="EN-US" style="font-size:12.0pt;line-height:150%;font-family:宋体">GND</span></p>
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<td style="width:207.4pt;border-top:none;border-left:none;
  border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;
  mso-border-top-alt:solid windowtext .5pt;mso-border-left-alt:solid windowtext .5pt;
  mso-border-alt:solid windowtext .5pt;padding:0cm 5.4pt 0cm 5.4pt" width="277">
<p align="center" class="MsoNormal" style="text-align:center;line-height:150%"><span lang="EN-US" style="font-size:12.0pt;line-height:150%;font-family:宋体">GND</span></p>
</td>
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<tr style="mso-yfti-irow:3;mso-yfti-lastrow:yes">
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<p align="center" class="MsoNormal" style="text-align:center;line-height:150%"><span lang="EN-US" style="font-size:12.0pt;line-height:150%;font-family:宋体">P0</span></p>
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<td style="width:207.4pt;border-top:none;border-left:none;
  border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;
  mso-border-top-alt:solid windowtext .5pt;mso-border-left-alt:solid windowtext .5pt;
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<p align="center" class="MsoNormal" style="text-align:center;line-height:150%"><span lang="EN-US" style="font-size:12.0pt;line-height:150%;font-family:宋体">AOUT</span></p>
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<p class="MsoNormal" style="line-height:150%"><span style="font-size:12.0pt;
line-height:150%;font-family:宋体">具体硬件连接如下图所示：<span lang="EN-US"></span></span></p>
<p>[[File:Micro：bit系列教程17：Liquid_Level_Sensor液位检测-0.png|400px]]</p>
<h1 style="line-height:150%"><span lang="EN-US" style="font-size:15.0pt;
line-height:150%;font-family:黑体;font-weight:normal;mso-bidi-font-weight:bold">3.</span><span style="font-size:15.0pt;line-height:150%;font-family:黑体;font-weight:normal;
mso-bidi-font-weight:bold">软件设计<span lang="EN-US"></span></span></h1>
<p class="MsoNormal" style="line-height:150%"><span lang="EN-US"><span style="mso-tab-count:1">    </span></span><span style="font-size:12.0pt;
line-height:150%;font-family:宋体">打开<span lang="EN-US">makecode</span>，添加软件包，输入以下链接：<span lang="EN-US"></span></span></p>
<p class="MsoNormal" style="line-height:150%"><span lang="EN-US"><span style="font-size:12.0pt;
line-height:150%;font-family:宋体">https://github.com/waveshare/CourseKit</span></span><span class="MsoHyperlink"><span lang="EN-US" style="font-size:12.0pt;line-height:150%;
font-family:宋体"></span></span></p>
<p class="MsoNormal" style="line-height:150%"><span style="font-size:12.0pt;
line-height:150%;font-family:宋体">添加软件包成功后，采用积木块编写以下程序：<span lang="EN-US"></span></span></p>
<p>[[File:Micro：bit系列教程17：Liquid_Level_Sensor液位检测-1.png|400px]]</p>
<p class="MsoNormal" style="line-height:150%"><span style="font-size:12.0pt;
line-height:150%;font-family:宋体">下载，点击显示数据<span lang="EN-US">(</span>设备<span lang="EN-US">),</span>可观测<span lang="EN-US">Micro:bit</span>读取<span lang="EN-US">Liquid
Level Sensor</span>模块的<span lang="EN-US">ADC</span>值及转换后的电压值<span lang="EN-US">(mv)</span>：<span lang="EN-US"></span></span></p>
<p>[[File:Micro：bit系列教程17：Liquid_Level_Sensor液位检测-2.png|400px]]</p>
<p class="MsoNormal" style="line-height:150%"><span style="font-size:12.0pt;
line-height:150%;font-family:宋体">由图中数据可得，当将<span lang="EN-US">Liquid Level Sensor</span>模块插入到液体时，输出的<span lang="EN-US">ADC</span>值逐渐升高，相应的电压值也不断升高，可根据下表初略估计插入液位深度与电压的关系：<span lang="EN-US"></span></span></p>
<p class="MsoNormal" style="line-height:150%"><span lang="EN-US" style="font-size:
12.0pt;line-height:150%;font-family:宋体"></span></p>
<div align="center">
<table border="1" cellpadding="0" cellspacing="0" class="MsoTableGrid" style="border-collapse:collapse;border:none;mso-border-alt:solid windowtext .5pt;
 mso-yfti-tbllook:1184;mso-padding-alt:0cm 5.4pt 0cm 5.4pt">
<tr style="mso-yfti-irow:0;mso-yfti-firstrow:yes;height:19.9pt">
<td style="width:158.85pt;border:solid windowtext 1.0pt;mso-border-alt:
  solid windowtext .5pt;padding:0cm 5.4pt 0cm 5.4pt;height:19.9pt" width="212">
<p align="center" class="MsoNormal" style="text-align:center;line-height:150%"><span style="font-size:12.0pt;line-height:150%;font-family:宋体">水位高度<span lang="EN-US"></span></span></p>
</td>
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<p align="center" class="MsoNormal" style="text-align:center;line-height:150%"><span style="font-size:12.0pt;line-height:150%;font-family:宋体">输出电压值<span lang="EN-US"></span></span></p>
</td>
</tr>
<tr style="mso-yfti-irow:1;height:19.9pt">
<td style="width:158.85pt;border:solid windowtext 1.0pt;border-top:
  none;mso-border-top-alt:solid windowtext .5pt;mso-border-alt:solid windowtext .5pt;
  padding:0cm 5.4pt 0cm 5.4pt;height:19.9pt" width="212">
<p align="center" class="MsoNormal" style="text-align:center;line-height:150%"><span lang="EN-US" style="font-size:12.0pt;line-height:150%;font-family:宋体">0cm</span></p>
</td>
<td style="width:158.85pt;border-top:none;border-left:none;
  border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;
  mso-border-top-alt:solid windowtext .5pt;mso-border-left-alt:solid windowtext .5pt;
  mso-border-alt:solid windowtext .5pt;padding:0cm 5.4pt 0cm 5.4pt;height:19.9pt" width="212">
<p align="center" class="MsoNormal" style="text-align:center;line-height:150%"><span lang="EN-US" style="font-size:12.0pt;line-height:150%;font-family:宋体">0mV</span></p>
</td>
</tr>
<tr style="mso-yfti-irow:2;height:20.45pt">
<td style="width:158.85pt;border:solid windowtext 1.0pt;border-top:
  none;mso-border-top-alt:solid windowtext .5pt;mso-border-alt:solid windowtext .5pt;
  padding:0cm 5.4pt 0cm 5.4pt;height:20.45pt" width="212">
<p align="center" class="MsoNormal" style="text-align:center;line-height:150%"><span lang="EN-US" style="font-size:12.0pt;line-height:150%;font-family:宋体">0.5cm</span></p>
</td>
<td style="width:158.85pt;border-top:none;border-left:none;
  border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;
  mso-border-top-alt:solid windowtext .5pt;mso-border-left-alt:solid windowtext .5pt;
  mso-border-alt:solid windowtext .5pt;padding:0cm 5.4pt 0cm 5.4pt;height:20.45pt" width="212">
<p align="center" class="MsoNormal" style="text-align:center;line-height:150%"><span lang="EN-US" style="font-size:12.0pt;line-height:150%;font-family:宋体">1300mV</span></p>
</td>
</tr>
<tr style="mso-yfti-irow:3;height:19.9pt">
<td style="width:158.85pt;border:solid windowtext 1.0pt;border-top:
  none;mso-border-top-alt:solid windowtext .5pt;mso-border-alt:solid windowtext .5pt;
  padding:0cm 5.4pt 0cm 5.4pt;height:19.9pt" width="212">
<p align="center" class="MsoNormal" style="text-align:center;line-height:150%"><span lang="EN-US" style="font-size:12.0pt;line-height:150%;font-family:宋体">1.0cm</span></p>
</td>
<td style="width:158.85pt;border-top:none;border-left:none;
  border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;
  mso-border-top-alt:solid windowtext .5pt;mso-border-left-alt:solid windowtext .5pt;
  mso-border-alt:solid windowtext .5pt;padding:0cm 5.4pt 0cm 5.4pt;height:19.9pt" width="212">
<p align="center" class="MsoNormal" style="text-align:center;line-height:150%"><span lang="EN-US" style="font-size:12.0pt;line-height:150%;font-family:宋体">1530mV</span></p>
</td>
</tr>
<tr style="mso-yfti-irow:4;height:19.9pt">
<td style="width:158.85pt;border:solid windowtext 1.0pt;border-top:
  none;mso-border-top-alt:solid windowtext .5pt;mso-border-alt:solid windowtext .5pt;
  padding:0cm 5.4pt 0cm 5.4pt;height:19.9pt" width="212">
<p align="center" class="MsoNormal" style="text-align:center;line-height:150%"><span lang="EN-US" style="font-size:12.0pt;line-height:150%;font-family:宋体">1.5cm</span></p>
</td>
<td style="width:158.85pt;border-top:none;border-left:none;
  border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;
  mso-border-top-alt:solid windowtext .5pt;mso-border-left-alt:solid windowtext .5pt;
  mso-border-alt:solid windowtext .5pt;padding:0cm 5.4pt 0cm 5.4pt;height:19.9pt" width="212">
<p align="center" class="MsoNormal" style="text-align:center;line-height:150%"><span lang="EN-US" style="font-size:12.0pt;line-height:150%;font-family:宋体">1620mV</span></p>
</td>
</tr>
<tr style="mso-yfti-irow:5;height:19.9pt">
<td style="width:158.85pt;border:solid windowtext 1.0pt;border-top:
  none;mso-border-top-alt:solid windowtext .5pt;mso-border-alt:solid windowtext .5pt;
  padding:0cm 5.4pt 0cm 5.4pt;height:19.9pt" width="212">
<p align="center" class="MsoNormal" style="text-align:center;line-height:150%"><span lang="EN-US" style="font-size:12.0pt;line-height:150%;font-family:宋体">2.0cm</span></p>
</td>
<td style="width:158.85pt;border-top:none;border-left:none;
  border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;
  mso-border-top-alt:solid windowtext .5pt;mso-border-left-alt:solid windowtext .5pt;
  mso-border-alt:solid windowtext .5pt;padding:0cm 5.4pt 0cm 5.4pt;height:19.9pt" width="212">
<p align="center" class="MsoNormal" style="text-align:center;line-height:150%"><span lang="EN-US" style="font-size:12.0pt;line-height:150%;font-family:宋体">1690mV</span></p>
</td>
</tr>
<tr style="mso-yfti-irow:6;height:19.9pt">
<td style="width:158.85pt;border:solid windowtext 1.0pt;border-top:
  none;mso-border-top-alt:solid windowtext .5pt;mso-border-alt:solid windowtext .5pt;
  padding:0cm 5.4pt 0cm 5.4pt;height:19.9pt" width="212">
<p align="center" class="MsoNormal" style="text-align:center;line-height:150%"><span lang="EN-US" style="font-size:12.0pt;line-height:150%;font-family:宋体">2.5cm</span></p>
</td>
<td style="width:158.85pt;border-top:none;border-left:none;
  border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;
  mso-border-top-alt:solid windowtext .5pt;mso-border-left-alt:solid windowtext .5pt;
  mso-border-alt:solid windowtext .5pt;padding:0cm 5.4pt 0cm 5.4pt;height:19.9pt" width="212">
<p align="center" class="MsoNormal" style="text-align:center;line-height:150%"><span lang="EN-US" style="font-size:12.0pt;line-height:150%;font-family:宋体">1740mV</span></p>
</td>
</tr>
<tr style="mso-yfti-irow:7;height:19.9pt">
<td style="width:158.85pt;border:solid windowtext 1.0pt;border-top:
  none;mso-border-top-alt:solid windowtext .5pt;mso-border-alt:solid windowtext .5pt;
  padding:0cm 5.4pt 0cm 5.4pt;height:19.9pt" width="212">
<p align="center" class="MsoNormal" style="text-align:center;line-height:150%"><span lang="EN-US" style="font-size:12.0pt;line-height:150%;font-family:宋体">3.0cm</span></p>
</td>
<td style="width:158.85pt;border-top:none;border-left:none;
  border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;
  mso-border-top-alt:solid windowtext .5pt;mso-border-left-alt:solid windowtext .5pt;
  mso-border-alt:solid windowtext .5pt;padding:0cm 5.4pt 0cm 5.4pt;height:19.9pt" width="212">
<p align="center" class="MsoNormal" style="text-align:center;line-height:150%"><span lang="EN-US" style="font-size:12.0pt;line-height:150%;font-family:宋体">1770mV</span></p>
</td>
</tr>
<tr style="mso-yfti-irow:8;height:20.45pt">
<td style="width:158.85pt;border:solid windowtext 1.0pt;border-top:
  none;mso-border-top-alt:solid windowtext .5pt;mso-border-alt:solid windowtext .5pt;
  padding:0cm 5.4pt 0cm 5.4pt;height:20.45pt" width="212">
<p align="center" class="MsoNormal" style="text-align:center;line-height:150%"><span lang="EN-US" style="font-size:12.0pt;line-height:150%;font-family:宋体">3.5cm</span></p>
</td>
<td style="width:158.85pt;border-top:none;border-left:none;
  border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;
  mso-border-top-alt:solid windowtext .5pt;mso-border-left-alt:solid windowtext .5pt;
  mso-border-alt:solid windowtext .5pt;padding:0cm 5.4pt 0cm 5.4pt;height:20.45pt" width="212">
<p align="center" class="MsoNormal" style="text-align:center;line-height:150%"><span lang="EN-US" style="font-size:12.0pt;line-height:150%;font-family:宋体">1810mV</span></p>
</td>
</tr>
<tr style="mso-yfti-irow:9;height:19.9pt">
<td style="width:158.85pt;border:solid windowtext 1.0pt;border-top:
  none;mso-border-top-alt:solid windowtext .5pt;mso-border-alt:solid windowtext .5pt;
  padding:0cm 5.4pt 0cm 5.4pt;height:19.9pt" width="212">
<p align="center" class="MsoNormal" style="text-align:center;line-height:150%"><span lang="EN-US" style="font-size:12.0pt;line-height:150%;font-family:宋体">4.0cm</span></p>
</td>
<td style="width:158.85pt;border-top:none;border-left:none;
  border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;
  mso-border-top-alt:solid windowtext .5pt;mso-border-left-alt:solid windowtext .5pt;
  mso-border-alt:solid windowtext .5pt;padding:0cm 5.4pt 0cm 5.4pt;height:19.9pt" width="212">
<p align="center" class="MsoNormal" style="text-align:center;line-height:150%"><span lang="EN-US" style="font-size:12.0pt;line-height:150%;font-family:宋体">1840mV</span></p>
</td>
</tr>
<tr style="mso-yfti-irow:10;height:19.9pt">
<td style="width:158.85pt;border:solid windowtext 1.0pt;border-top:
  none;mso-border-top-alt:solid windowtext .5pt;mso-border-alt:solid windowtext .5pt;
  padding:0cm 5.4pt 0cm 5.4pt;height:19.9pt" width="212">
<p align="center" class="MsoNormal" style="text-align:center;line-height:150%"><span lang="EN-US" style="font-size:12.0pt;line-height:150%;font-family:宋体">4.5cm</span></p>
</td>
<td style="width:158.85pt;border-top:none;border-left:none;
  border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;
  mso-border-top-alt:solid windowtext .5pt;mso-border-left-alt:solid windowtext .5pt;
  mso-border-alt:solid windowtext .5pt;padding:0cm 5.4pt 0cm 5.4pt;height:19.9pt" width="212">
<p align="center" class="MsoNormal" style="text-align:center;line-height:150%"><span lang="EN-US" style="font-size:12.0pt;line-height:150%;font-family:宋体">1860mV</span></p>
</td>
</tr>
<tr style="mso-yfti-irow:11;mso-yfti-lastrow:yes;height:19.9pt">
<td style="width:158.85pt;border:solid windowtext 1.0pt;border-top:
  none;mso-border-top-alt:solid windowtext .5pt;mso-border-alt:solid windowtext .5pt;
  padding:0cm 5.4pt 0cm 5.4pt;height:19.9pt" width="212">
<p align="center" class="MsoNormal" style="text-align:center;line-height:150%"><span lang="EN-US" style="font-size:12.0pt;line-height:150%;font-family:宋体">4.8cm</span></p>
</td>
<td style="width:158.85pt;border-top:none;border-left:none;
  border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;
  mso-border-top-alt:solid windowtext .5pt;mso-border-left-alt:solid windowtext .5pt;
  mso-border-alt:solid windowtext .5pt;padding:0cm 5.4pt 0cm 5.4pt;height:19.9pt" width="212">
<p align="center" class="MsoNormal" style="text-align:center;line-height:150%"><span lang="EN-US" style="font-size:12.0pt;line-height:150%;font-family:宋体">1880mV</span></p>
</td>
</tr>
</table>
</div>
<p class="MsoNormal" style="line-height:150%"><span lang="EN-US" style="font-size:
12.0pt;line-height:150%;font-family:宋体"></span></p>