（79）【按键】[独立按键] - 1： 单击，双击，三击以及N击

此按键程序的实现的功能是单个独立按键的[单击]，[长按]，[双击]，[三击]以及[多击]。本文分为三个部分，

• 第一个部分是说[单击]，[长按]的程序；
• 第二部分是讲[双击]；
• 第三部分是讲[三击]，[N击]；
  

  一、 [单击]、[长按]程序

  1. 简单介绍本按键程序的单击和长按

  首先说一下单击，长按的响应情况，就是按多久算单击或者长按，按下按键马上返回有效键值，还是释放之后返回有效键值等等，下面说下它在什么情况下返回有效的【单击】和【长按】。

  首先看一张时序图：

• 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" 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• 注：
  T1：是单击的按键消抖时长，这里预设的是30ms，也可以根据需求自行定义；
  T2：是单击时，按键释放的有效时间段，提前或者超过这个时间段释放的按键都再是单击了。提前释放则是无效键值，超过后释放则是长按。
  T3：是长按时长，按键超过此时长，则为长按。这里的预设值是3s，同样可根据需求自行更改。
  【单击】：按键按下超过消抖时长T1(30ms)，并且在T2时间段内释放按键，按键一释放，马上返回有效按键值—【单击】。
  注意：单击是释放后，才返回有效按键值，不释放时，是无效按键值。

  【长按】：按键按下的时间超过预设的长按时长T3(3s) ，马上返回有效按键值—【长按】；
  注意：长按是只要按下的时间超过预设的长按时长，马上返回有效键值。但是，如果按键一直按着不释放，则只返回一次有效按键值，不重复返回，直到释放之后，才开始重新读取键值。
  2. 按键程序的架构

  按键程序可以分为四个部分，

  第一部分：判断有无按键按下；
      第二部分：按键是否有效（按键消抖）；
      第三部分：确定有效按键的种类（单击还是长按）；
      第四部分：等待按键释放。

  3. 按键程序的源代码以及注释
  以下是key.c 的源代码：

   //============================ key.c ===================
  
   #define KEY_INPUT           P1.0    // 按键IO
  
   #define KEY_STATE_0         0       // 按键状态
   #define KEY_STATE_1         1
   #define KEY_STATE_2         2
   #define KEY_STATE_3         3
  
   #define LONG_KEY_TIME       300     // LONG_KEY_TIME*10MS = 3S
   #define SINGLE_KEY_TIME     3       // SINGLE_KEY_TIME*10MS = 30MS
  
   #define N_KEY    0                  // no click
   #define S_KEY    1                  // single click
   #define L_KEY    10                 // long press
  
   unsigned char key_driver(void)
   {
       static unsigned char key_state = ;         // 按键状态变量
       static unsigned int key_time = ;           // 按键计时变量
       unsigned char key_press, key_return;
  
       key_return = N_KEY;                         // 清除 返回按键值
  
       key_press = KEY_INPUT;                      // 读取当前键值
  
       switch (key_state)
       {
           case KEY_STATE_0:                       // 按键状态0：判断有无按键按下
               if (!key_press)                     // 有按键按下
               {
                   key_time = ;                   // 清零时间间隔计数
                   key_state = KEY_STATE_1;        // 然后进入 按键状态1
               }
               break;
  
           case KEY_STATE_1:                       // 按键状态1：软件消抖（确定按键是否有效，而不是误触）。按键有效的定义：按键持续按下超过设定的消抖时间。
               if (!key_press)
               {
                   key_time++;                     // 一次10ms
                   if(key_time>=SINGLE_KEY_TIME)   // 消抖时间为：SINGLE_KEY_TIME*10ms = 30ms;
                   {
                       key_state = KEY_STATE_2;    // 如果按键时间超过 消抖时间，即判定为按下的按键有效。按键有效包括两种：单击或者长按，进入 按键状态2， 继续判定到底是那种有效按键
                   }
               }
               else key_state = KEY_STATE_0;       // 如果按键时间没有超过，判定为误触，按键无效，返回 按键状态0，继续等待按键
               break;
  
           case KEY_STATE_2:                       // 按键状态2：判定按键有效的种类：是单击，还是长按
               if(key_press)                       // 如果按键在 设定的长按时间 内释放，则判定为单击
               {
                    key_return = S_KEY;            // 返回 有效按键值：单击
                    key_state = KEY_STATE_0;       // 返回 按键状态0，继续等待按键
               }
               else
               {
                   key_time++;                     
  
                   if(key_time >= LONG_KEY_TIME)   // 如果按键时间超过 设定的长按时间（LONG_KEY_TIME*10ms=200*10ms=2000ms）, 则判定为 长按
                   {
                       key_return = L_KEY;         // 返回 有效键值值：长按
                       key_state = KEY_STATE_3;    // 去状态3，等待按键释放
                   }
               }
               break;
  
         case KEY_STATE_3:                         // 等待按键释放
             if (key_press)
             {
                 key_state = KEY_STATE_0;          // 按键释放后，进入 按键状态0 ，进行下一次按键的判定
             }
             break;
  
           default:                                // 特殊情况：key_state是其他值得情况，清零key_state。这种情况一般出现在 没有初始化key_state，第一次执行这个函数的时候
               key_state = KEY_STATE_0;
               break;
       }
  
       return key_return;                          // 返回 按键值
   } 

• 原文地址：https://blog.csdn.net/pillarpeng/article/details/50963127