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designiot
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	<head>
		<title>一步步搭建物联网系统(教你设计物联网系统)</title>
		<meta name="keywords" content="设计物联网系统,物联网系统设计">
		<meta name="description" content="一份关于如何设计物联网系统的文档">
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	<body class="container inner wrap">
		<h1>一步步搭建物联网系统(教你设计物联网系统)</h1>
	</body>
</html>
<div id="TOC">
<ul>
<li><a href="#简单物联网"><span class="toc-section-number">1</span> 简单物联网</a><ul>
<li><a href="#硬件通信"><span class="toc-section-number">1.1</span> 硬件通信</a><ul>
<li><a href="#串口通信"><span class="toc-section-number">1.1.1</span> 串口通信</a></li>
</ul></li>
<li><a href="#硬件"><span class="toc-section-number">1.2</span> 硬件</a><ul>
<li><a href="#arduino"><span class="toc-section-number">1.2.1</span> Arduino</a></li>
<li><a href="#继电器"><span class="toc-section-number">1.2.2</span> 继电器</a></li>
</ul></li>
</ul></li>
</ul>
</div>
<h1 id="简单物联网"><span class="header-section-number">1</span> 简单物联网</h1>
<p>到这时，我们算搭建了一个简单的REST服务了。接着我们可以简单的做一个最小的物联网系统，将我们的单片机、MCU等等连上网。</p>
<div class="figure">
<img src="./images/arch.jpeg" alt="硬件结构图" />
<p class="caption">硬件结构图</p>
</div>
<p>考虑到如果我们只是单一连接各个节点，那么系统的结构图，同下所示</p>
<div class="figure">
<img src="./images/fullconnected.png" alt="全连接" />
<p class="caption">全连接</p>
</div>
<p>下面的星形结构图类似于我们在接下来所要构建的系统</p>
<div class="figure">
<img src="./images/star.png" alt="星形结构图" />
<p class="caption">星形结构图</p>
</div>
<p>一个用于控制真实电器的硬件实物图</p>
<div class="figure">
<img src="./images/hardware.jpg" alt="简单实物图" />
<p class="caption">简单实物图</p>
</div>
<h2 id="硬件通信"><span class="header-section-number">1.1</span> 硬件通信</h2>
<h3 id="串口通信"><span class="header-section-number">1.1.1</span> 串口通信</h3>
<p>Arduino与Raspberry Pi通过串口通信的方式实现通信，相互传输所需要的数据，Raspberry Pi将资源传于互联网上对应的接口，接口可以在互联网上被访问。Laravel框架构架于服务器之上，将Raspbery Pi获取过来的数据存储于MySQL数据，再以REST服务的方式共享数据，互联网上的其他设备便可以通过网络来访问这些设备。Ajax用于将后台的数据以不需要刷新的方式传递到网站前台，通过HighCharts框架显示给终端用户。</p>
<h4 id="python"><span class="header-section-number">1.1.1.1</span> Python</h4>
<p>1.在Windows中的串口通常是<code>COM1</code>,<code>COM0</code>等等</p>
<div class="sourceCode"><pre class="sourceCode python"><code class="sourceCode python">ser<span class="op">=</span>serial.Serial(<span class="st">&quot;COM0&quot;</span>,<span class="dv">9600</span>)</code></pre></div>
<p>2.Mac OS系统中位于/dev目录下，名字类似于<code>tty.usbmodem1451</code>。</p>
<div class="sourceCode"><pre class="sourceCode python"><code class="sourceCode python">    serial.Serial(<span class="st">&quot;/dev/tty.usbmodem1451&quot;</span>,<span class="dv">9600</span>)</code></pre></div>
<p>3.在Linux内核的系统中虚拟串口用的节点是ttyACM，位于/dev目录下。</p>
<div class="sourceCode"><pre class="sourceCode python"><code class="sourceCode python">    serial.Serial(<span class="st">&quot;/dev/ttyACM0&quot;</span>,<span class="dv">9600</span>)</code></pre></div>
<blockquote>
<p>串行接口是一种可以将接受来自CPU的并行数据字符转换为连续的串行数据流发送出去，同时可将接受的串行数据流转换为并行的数据字符供给CPU的器件。一般完成这种功能 的电路，我们称为串行接口电路。</p>
</blockquote>
<p>便是打开这个设备，以9600的速率传输数据。</p>
<p>程序框架如下所示:</p>
<div class="figure">
<img src="./images/raspberrypi_flow.png" alt="Raspberry Pi" />
<p class="caption">Raspberry Pi</p>
</div>
<p>代码如下:</p>
<div class="sourceCode"><pre class="sourceCode python"><code class="sourceCode python"><span class="im">import</span> json
<span class="im">import</span> urllib2
<span class="im">import</span> serial
<span class="im">import</span> time

url<span class="op">=</span><span class="st">&quot;http://www.xianuniversity.com/athome/1&quot;</span>

<span class="cf">while</span> <span class="dv">1</span>:
    <span class="cf">try</span>:
        date<span class="op">=</span>urllib2.urlopen(url)
        result<span class="op">=</span>json.load(date)
        status<span class="op">=</span>result[<span class="dv">0</span>][<span class="st">&quot;led1&quot;</span>]
        ser<span class="op">=</span>serial.Serial(<span class="st">&quot;/dev/ttyACM0&quot;</span>,<span class="dv">9600</span>)
        <span class="cf">if</span> status<span class="op">==</span><span class="dv">1</span> :
            ser.write(<span class="st">&quot;1&quot;</span>)
        <span class="cf">elif</span> status<span class="op">==</span><span class="dv">0</span>:
            ser.write(<span class="st">&quot;0&quot;</span>)
        time.sleep(<span class="dv">1</span>)
    <span class="cf">except</span> urllib2.URLError:
        <span class="bu">print</span> <span class="st">&quot;Bad URL or timeout&quot;</span></code></pre></div>
<div class="figure">
<img src="./images/getjson.png" alt="python返回json数据" />
<p class="caption">python返回json数据</p>
</div>
<p>系统还需要对上面的数据进行处理，只拿其中的结果</p>
<div class="figure">
<img src="./images/origin.png" alt="python处理完后的结果" />
<p class="caption">python处理完后的结果</p>
</div>
<p>当改变led的状态后，便可以得到下面的结果</p>
<div class="figure">
<img src="./images/change.png" alt="改变状态后的结果" />
<p class="caption">改变状态后的结果</p>
</div>
<h4 id="ruby"><span class="header-section-number">1.1.1.2</span> Ruby</h4>
<p>如果你用的是Ruby的话，可以尝试使用<code>serialport</code></p>
<p>安装</p>
<div class="sourceCode"><pre class="sourceCode bash"><code class="sourceCode bash"><span class="kw">sudo</span> gem install serialport</code></pre></div>
<p>代码大致如下</p>
<div class="sourceCode"><pre class="sourceCode ruby"><code class="sourceCode ruby">require <span class="st">&#39;serialport&#39;</span>
sp = <span class="dt">SerialPort</span>.new <span class="st">&quot;/dev/ACM0&quot;</span>, <span class="dv">9600</span>
sp.write <span class="st">&quot;1&quot;</span></code></pre></div>
<p>注意: 根据相关的系统修改相关的代码。</p>
<h2 id="硬件"><span class="header-section-number">1.2</span> 硬件</h2>
<h3 id="arduino"><span class="header-section-number">1.2.1</span> Arduino</h3>
<p>这样我们在我们的Arduino上所要做的便是，读取串口的结果并控制IO口。</p>
<div class="sourceCode"><pre class="sourceCode c"><code class="sourceCode c"><span class="dt">int</span> ledPort=<span class="dv">13</span>;

<span class="dt">void</span> setup() {
  Serial.begin(<span class="dv">9600</span>);
  pinMode(ledPort,OUTPUT);
}

<span class="dt">int</span> serialData;
<span class="dt">void</span> loop() {
  String inString = <span class="st">&quot;&quot;</span>;
  <span class="kw">while</span> (Serial.available()&gt; <span class="dv">0</span>)
  {
    <span class="dt">int</span> inChar = Serial.read();
    <span class="kw">if</span> (isDigit(inChar)) {
      inString += (<span class="dt">char</span>)inChar; 
    }
    serialData=inString.toInt();
    Serial.print(serialData);
  }
  <span class="kw">if</span>(serialData==<span class="dv">1</span>){
    digitalWrite(ledPort,HIGH);
  }<span class="kw">else</span>{
    digitalWrite(ledPort,LOW);
  }
}</code></pre></div>
<p>如果结果是1的话，就让13口为高电平，也就是让灯亮起来。</p>
<h3 id="继电器"><span class="header-section-number">1.2.2</span> 继电器</h3>
<blockquote>
<p>继电器（英文名称：relay）是一种电控制器件，是当输入量（激励量）的变化达到规定要求时，在电气输出电路中使被控量发生预定的阶跃变化的一种电器。它具有控制系统（又称输入回路）和被控制系统（又称输出回路）之间的互动关系。通常应用于自动化的控制电路中，它实际上是用小电流去控制大电流运作的一种“自动开关”。故在电路中起着自动调节、安全保护、转换电路等作用。</p>
</blockquote>
<p>在这里我们可以默认为我们想要为单片机的5V电压控制220V的电器。</p>
<p>最后我们便可以通过些来控制灯的开和关。</p>
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