//单片机型号STC12C5204AD
//按键输入口：P2^0,P2^1
//输出端口：P2^2

 #include

 #define   null        0x00
 #define   bit_0       0x01
 #define   bit_1       0x02
 #define   bit_2       0x04
 #define   bit_3       0x08
 #define   bit_4       0x10
 #define   bit_5       0x20
 #define   bit_6       0x40
 #define   bit_7       0x80
 #define   uchar       unsigned char 
 #define   suchar      static unsigned  char
 #define   uint        unsigned int
 #define   suint       static unsigned int
 #define   cuchar      const  unsigned char

#define   uchar       unsigned char 
sbit      OUT_LIGHT = P2^2;      //定义背光驱动口

bit         LOCK=0;
char        keybitbuf;

//$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
typedef struct             // 按键处理用
 { uchar timebuf[8];
   uchar hadpresskey;
 } PressKey;
   PressKey  presskey;

#define   WAITCIRCLETIMENUM    10// 20   //等待延时次数

/*按键检测*/
char lookForKey(PressKey *b,uchar *a,uchar BITNUM)
  { uchar m,n;
    n=BITNUM,m=0;
   while (!(n&1)) { m+=1;n=n>>1;}
   if     (b->hadpresskey&(*a)&BITNUM) 
         { b->hadpresskey&=~BITNUM;
           return(BITNUM);
   }
    else { if    (*a&BITNUM)     
             {  b->timebuf[m]=0;
       b->hadpresskey&=~BITNUM;
    }
        else {  if   (b->timebuf[m]>=WAITCIRCLETIMENUM )
                 { b->hadpresskey|=BITNUM; 
          b->timebuf[m]=0;
        }
                   else {b->timebuf[m]++; }
    }
       }
    return(0);
  }

 //$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$

//$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
//程序的调用
void main()
{
while(1)
{
 keybitbuf=P2;  //P2表示单片机的P2口
   if  (lookForKey(&presskey,&keybitbuf,0x02))    {OUT_LIGHT=~OUT_LIGHT;}     //0X02表示P2.1口，0X01表示P2.0，0X04表示P2.2 ，0X08表示P2.3，0X10表示P2.4
   if  (lookForKey(&presskey,&keybitbuf,0x01))    {OUT_LIGHT=~OUT_LIGHT; ;}  
    if  (lookForKey(&presskey,&keybitbuf,0x20))    {  ;}
}
}