51中的 外部中断

外部中断的程序和time0、time1的程序差不多： 
一、打开外部中断

<code class="hljs fix has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-attribute" style="box-sizing: border-box;">EA </span>=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;"> 1;</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul>

二、设置外部中断触发方式

<code class="hljs fix has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-attribute" style="box-sizing: border-box;">IT0 </span>=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;"> 1;    //INT0中断请求触发，1为负边沿触发</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul>

三、打开外部中断函数

<code class="hljs fix has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-attribute" style="box-sizing: border-box;">EX0 </span>=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;"> 1;  //enable int0</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul>

四、编写外部中断函数

<code class="hljs cs has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> ISR_Exit0(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span>) interrupt <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>{    EX0 = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>;    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">/*    task    */</span>    EX0 = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>;}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li></ul>

中断的嵌套

两个中断一个在运行时，另一个突然中断，判断优先级后，由优先级高的先运行。

用外部中断和一个中断实现闹钟

<code class="hljs cpp has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#include <reg52.h></span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#include "./delay/delay.h"</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#define SEGPORT P0</span>sbit key1 = P3^<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>;sbit bit_sel = P2^<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>;sbit seg_sel = P2^<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>;<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">unsigned</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span> segdata[<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">16</span>] = {<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0x3f</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0x06</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0x5b</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0x4f</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0x66</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0x6d</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0x7d</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0x07</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0x7f</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0x6f</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0x77</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0x7c</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0x39</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0x5e</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0x79</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0x71</span>};<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">unsigned</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span> coode[<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">8</span>] = {<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0xfe</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0xfd</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0xfb</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0xf7</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0xef</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0xdf</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0xbf</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0x7f</span>};<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">unsigned</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span> outdata[<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>] = {<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0x3f</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0x3f</span>};<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> timer0(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span>){    EA = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>;    TMOD |= <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0x01</span>;    TH0 = (<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">65536</span>-<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">20000</span>)/<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">256</span>;    TL0 = (<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">65536</span>-<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">20000</span>)%<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">256</span>;    ET0 = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>;    TR0 = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>;}<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> display(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span>){     <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">static</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">unsigned</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span> i = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>;     SEGPORT = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0xff</span>;             bit_sel = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>;     bit_sel = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>;     SEGPORT = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0x0</span>;     seg_sel = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>;     seg_sel = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>;     SEGPORT = coode[i];     bit_sel = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>;     bit_sel = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>;     SEGPORT = outdata[i];     seg_sel = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>;     seg_sel = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>;     i++;     <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span>(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span> == i)     {        i = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>;      }}<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> timer0_isr(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span>) interrupt <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>{    TH0 = (<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">65536</span>-<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2000</span>) / <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">256</span>;    TL0 = (<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">65536</span>-<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2000</span>) % <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">256</span>;    display();}<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> int0_init(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span>){    EA = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>;    IT0 = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>;    EX0 = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>;}<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> main(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span>){     int0_init();     timer0();     <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">while</span>(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>);}<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> int0_isr(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span>) interrupt <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>{    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">static</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">unsigned</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span> disdata = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>;    delay_ms(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">10</span>);    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span>(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span> == key1)    {         <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">while</span>(!key1);         delay_ms(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">10</span>);         <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">while</span>(!key1);         disdata++;         <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span>(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">100</span> == disdata)         {             disdata = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>;          }     }                          outdata[<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>] = segdata[disdata / <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">10</span>];    outdata[<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>] = segdata[disdata % <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">10</span>];}</code>