key.c

一个对4X4数字键盘进行行&列扫描,获取扫描码的程序,支持符合键,串键,软件去抖.

/*  
连线定义：
	C51 ~~ Key

	P1.0-7  = DB.0-7
*/  
#include <c51.h>

//   define  P1.0--P1.7
sbit  P10=P1^0;
sbit  P11=P1^1;
sbit  P12=P1^2;
sbit  P13=P1^3;
sbit  P14=P1^4;
sbit  P15=P1^5;
sbit  P16=P1^6;
sbit  P17=P1^7;

/*
char  keyBuf[KEY_RINGBUF_LENGTH];  // key ring buffer
int   iKeyHead;                       // pointer. for head
int   iKeyTail;                       // pointer for tail
*/
char  ScanCode[4]={0xfe,0xfd,0xfb,0xf7};  
char  key;                         
//int   latency;                     // define the keyboard sensity


void keyInit(void)             //initialize key board
{
   TMOD=0x20;   // T1=mod2
   TH1=0xfd;   //baudrate=9600
   TL1=0xfd;   
   PCON=0x00;   
   SCON=0x50;   // serial=mod1
   TR1=1;
   ES=0;
   EA=0;
   TI=0;
/*   iKeyHead=0;
   iKeyTail=0;*/
   }

int ScanKey(struct KeyStatus *ks)   //scan keyboard to get key code
{                                   // if any key pressed, return key code.
                                    // if pressed, only return code once.
   int c;
   int i,j;
   int key;
   
   ks->NowStatus=KEY_UP;
   for (i=0; i<4; i++) //scan
      {
	   c=ScanCode[i];
	   P1=(c<<4)|0x0f;
       delay(5);
	   c=P1 &0x0f;
	   if ( c  ==0x0f) continue;
	   for (j=0; j<4; j++)   //look up in the scancode tabel
		    if (!( c & (1<<j) ))
    		   {
			    key=(i<<2)+j;
#ifdef INCLUDE_CONTROL

       if      ( key==KEY_CTRL)  ks->Ctrl |= CTRL_CODE;
	            else if ( key==KEY_SHIFT)  ks->Ctrl |= SHIFT_CODE;
	            else
#endif
		    	        {
				        ks->NowStatus=KEY_DOWN;
						ks->Key=key;
						};
   		  	   };
      }

      if (ks->NowStatus==KEY_DOWN && ks->PreStatus==KEY_UP)
 	  {
	      ks->PreStatus=KEY_DOWN;
	      return 1;
	  };
/*	  ks->Ctrl=0;*/
      ks->PreStatus=ks->NowStatus;  //still pressed,and not released yet
   return 0;
}



// define the return value  
#define  ENTER    1    // get a line of input
#define  CANCEL   0    // canceled the input
#define  PAGEUP   2    // page up, need process last page of input 


int  Edln(char buf[CHAR_BUFFER_LENGTH] )   // edit a line ,and displayed on LCD
{
    struct KeyStatus ks;
    char  cnt;
    char c;

	cnt=0;
    ks.PreStatus=ks.NowStatus=KEY_UP;
    while (cnt<CHAR_BUFFER_LENGTH)  // avoid overflowing
    {
      if (ScanKey(&ks))             //get a new key
	      c=ks.Key;
	  else  continue;

	  switch  (c)
  	  {  
	      case KEY1:   c='1'; break;
		  case KEY2:   c='2'; break;  
		  case KEY3:   c='3'; break;
		  case KEY4:   c='4'; break;
		  case KEY5:   c='5'; break;
		  case KEY6:   c='6'; break;
		  case KEY7:   c='7'; break;
		  case KEY8:   c='8'; break;
		  case KEY9:   c='9'; break;
		  case KEY0:   c='0'; break;
		  case KEY_DOT:   c='.'; break;
		  case KEY_SUB:   c='-'; break;
		  case KEY_ENTER:
		       buf[cnt]=0;
			   while (ks.PreStatus==KEY_DOWN)
			     	  ScanKey(&ks);
				  
			   return ENTER;
		  case KEY_BACKSPACE:
		       if (cnt==0) continue;
			   cnt--;

 			   lcdInstruction(LCD_SET_DDRAM| (cnt>>1) |0x10 );  
		       prtc(' ');
		       prtc(' ');                      //clear one block
               delay(10);
 			   lcdInstruction(LCD_SET_DDRAM| (cnt>>1) |0x10 );  
			   if (cnt&0x01)
			       prtc(buf[cnt-1]);           // redraw the unaffected char

			   continue;
		  case KEY_CANCEL:
		       return CANCEL;
		  case KEY_PAGEUP:
		       return PAGEUP;
	   };
       buf[cnt]=c;
	   cnt++;            
	   prtc(c);              //displayed on LCD
	};
}