AVR 单片机 键盘子程序

键盘扫描有中断方式和查询方式 
#include "jn8515def.h" 

/******以下是键盘排列图****** 
                   |       |       |

PC0  ___1|__2|__3|__ 
                    |      |        | 
PC1  ___4|__5|__6|__ 
                   |       |        | 
PC2  ___7|__8|__9|__ 
                    |       |       | 
PC3  ___C|__0|__S|__   
                    |       |       | 
                    |       |       | 
               PC4 PC5 PC6 
*****************************/    
//下沿为有效键值          0    1    2    3    4    5    6    7    8    9  s(10)  c0   c1   c4   c7   cs  c 
flash uchar cKeyTab[]={0x57,0x6e,0x5e,0x3e,0x6d,0x5d,0x3d,0x6b,0x5b,0x3b,0x37,0x47,0x66,0x65,0x63,0x27,0x67}; 
flash uchar cKeyOut[]={0xef,0xdf,0xbf};           //其中一列为0 
flash uchar cKeyDir[]={0x10,0x20,0x40};   
uchar cMenu=0;  

uchar cKeyVal() 
{  statIC uchar cLastKv,cSameKvNum=0;   
   static   bit bKeyPress=0; 
   uchar i,j,cKeytmp=0xff; 
   for(i=0;i<3;i++) 
   {  DDRC&=0x80; 
      DDRC|=cKeyDir[i]; 
      PORTC=cKeyOut[i];    
      #asm("nop") 
      #asm("nop") 
      cKeytmp=PINC&0x7f;    
      for(j=0;j<16;j++) 
      {  if(cKeyTab[j]==cKeytmp) 
         {  cWaitTime=10;          //延时去抖 
            goto Next;    
         } 
      } 
   } 
  // do{                           //等待按键释放 
   // }while(!bKeyPress);     
   cSameKvNum=0;   
   bKeyPress=0; 
   return 0xff; 
Next:  
//   delay_ms(2);     
   if(bKeyPress) return 0xff; 
   if(cKeytmp==cLastKv)                  
   {  if(++cSameKvNum>10) 
      {  cSameKvNum=0; 
         bKeyPress=1; 
         return j; 
      } 
   } 
   else 
   {  cSameKvNum=0;   
      cLastKv=cKeytmp; 
   } 
      
   return 0xff;//返回空键值      
}