常用接口电路及其编程.htm

电压计(c语言编写的) 通过led灯显示 电路图说明： 1、R1、R2、D1、D2 组成发光二极管显示

lang=EN-US>“</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">日</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'">字形，另一个贺点形的发光管在显示器的右下角作为显示小数点用，它能显示各种数字及部份英文字母。</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">LED</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">显示器有两种不同的形式：一种是</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">8</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">个发光二极管的阳极都连在一起的，称之为共阳极</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">LED</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">显示器；另一种是</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">8</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">个发光二极管的阴极都连在一起的，称之为共阴极</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">LED</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">显示器。如下图所示。</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">`</SPAN></P>
<P style="MARGIN-LEFT: 36pt"><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">共阴和共阳结构的</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">LED</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">显示器各笔划段名和安排位置是相同的。当二极管导通时，相应的笔划段发亮，由发亮的笔划段组合而显示的各种字符。</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">8</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">个笔划段</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">hgfedcba</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">对应于一个字节（</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">8</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">位）的</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">D7 D6 D5 D4 D3 D2 D1 D0,</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">于是用</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">8</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">位二进制码就可以表示欲显示字符的字形代码。例如，对于共阴</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">LED</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">显示器，当公共阴极接地（为零电平），而阳极</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">hgfedcba</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">各段为</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">0111011</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">时，显示器显示</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">"P"</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">字符，即对于共阴极</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">LED</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">显示器，</SPAN><SPAN 
lang=EN-US>“</SPAN><SPAN lang=EN-US style="FONT-FAMILY: System">P</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'">字符的字形码是</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">73H</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">。如果是共阳</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">LED</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">显示器，公共阳极接高电平，显示</SPAN><SPAN 
lang=EN-US>“</SPAN><SPAN lang=EN-US style="FONT-FAMILY: System">P</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'">字符的字形代码应为</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">10001100</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 style="FONT-FAMILY: System">8CH</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">）。这里必须注意的是：很多产品为方便接线，常不按规则的方法去对应字段与位的关系，这时字形码就必须根据接线来自行设计了，后面我们会给出一个例子。</SPAN></P>
<P 
style="MARGIN-LEFT: 36pt; TEXT-INDENT: -18pt; mso-list: l0 level1 lfo4; tab-stops: list 36.0pt"><![if !supportLists]><SPAN 
lang=EN-US>2.<SPAN 
style="FONT: 7pt 'Times New Roman'">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
</SPAN></SPAN><![endif]><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">静态显示接口</SPAN></P>
<P><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">在单片机应用系统中，显示器显示常用两种方法：静态显示和动态扫描显示。所谓静态显示，就是每一个显示器都要占用单独的具有锁存功能的</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">I/O</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">接口用于笔划段字形代码。这样单片机只要把要显示的字形代码发送到接口电路，就不用管它了，直到要显示新的数据时，再发送新的字形码，因此，使用这种方法单片机中</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">CPU</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">的开销小。可以提供单独锁存的</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">I/O</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">接口电路很多，这里以常用的串并转换电路</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">74LS164</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">为例，介绍一种常用静态显示电路，以使大家对静态显示有一定的了解。</SPAN></P>
<P><SPAN lang=EN-US style="FONT-FAMILY: System">MCS-51</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">单片机串行口方式押为移们寄存器方式，外接</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">6</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">片</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">74LS164</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">作为</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">6</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">位</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">LED</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">显示器的静态显示接口，把</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">8031</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">的</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">RXD</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">作为数据输出线，</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">TXD</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">作为移位时钟脉冲。</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">74LS164</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">为</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">TTL</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">单向</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">8</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">位移位寄存器，可实现串行输入，并行输出。其中</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">A</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 style="FONT-FAMILY: System">B</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">（第</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">1</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 style="FONT-FAMILY: System">2</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">脚）为串行数据输入端，</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">2</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">个引脚按逻辑与运算规律输入信号，公一个输入信号时可并接。</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">T</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">（第</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">8</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">脚）为时钟输入端，可连接到串行口的</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">TXD</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">端。每一个时钟信号的上升沿加到</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">T</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">端时，移位寄存器移一位，</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">8</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">个时钟脉冲过后，</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">8</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">位二进制数全部移入</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">74LS164</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">中。</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">R</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">（第</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">9</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">脚）为复位端，当</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">R=0</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">时，移位寄存器各位复</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">0</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">，只有当</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">R=1</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">时，时钟脉冲才起作用。</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">Q1</SPAN><SPAN lang=EN-US>…</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">Q8</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">（第</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">3-6</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">和</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">10-13</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">引脚）并行输出端分别接</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">LED</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">显示器的</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">hg---a</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">各段对应的引脚上。关于</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">74LS164</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">还可以作如下的介绍：所谓时钟脉冲端，其实就是需要高、低、高、低的脉冲，不管这个脉冲是怎么来的，比如，我们用根电线，一端接</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">T</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">，一端用手拿着，分别接高电平、低电平，那也是给出时钟脉冲，在</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">74LS164</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">获得时钟脉冲的瞬间（再讲清楚点，是在脉冲的沿），如果数据输入端（第</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">1</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 style="FONT-FAMILY: System">2</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">引脚）是高电平，则就会有一个</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">1</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">进入到</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">74LS164</SPAN><SPAN 
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">的内部，如果数据输入端是低电平，则就会有一个</SPAN><SPAN 
lang=EN-US style="FONT-FAMILY: System">0</SPAN><SPAN