#include<reg51.h>
#include<absacc.h>
#define uint unsigned int
#define uchar unsigned char
/*********延時程序****************/
void delay_10ms(void) 
{ uchar i,j; 
 for(i=2000;i>0;i--) 
 for(j=24800;j>0;j--);
}  
  
/****掃描按鍵函數******/
uchar keyscan(void)
{
 uchar temp;  	
 uchar key=20;
 
 P1=0x7f;
  temp=P1;
  temp=temp&0x0f;
   if(temp!=0x0f)
	{

	delay_10ms();
	    switch(temp&0x0f)
		{                                                                                           


		case 0x0e:
 	    key=4;
		break;
		case 0x0d:
 	    key=8;
		break;
		case 0x0b:
 	    key=13;
		break;
	    case 0x07:
 	    key=16;
		break;
		default:break;
		}

	}


  P1=0xbf;
  temp=P1;
  temp=temp&0x0f;
   if(temp!=0x0f)
	{

	delay_10ms();
	    switch(temp&0x0f)
		{                                                                                           


		case 0x0e:
 	    key=3;
		break;
		case 0x0d:
 	    key=7;
		break;
		case 0x0b:
 	    key=11;
		break;
	    case 0x07:
 	    key=15;
		break;
		default:break;
		}

	}


  P1=0xdf;
  temp=P1;
  temp=temp&0x0f;
   if(temp!=0x0f)
	{

	delay_10ms();
	    switch(temp&0x0f)
		{                                                                                           


		case 0x0e:
 	    key=2;
		break;
		case 0x0d:
 	    key=6;
		break;
		case 0x0b:
 	    key=10;
		break;
	    case 0x07:
 	    key=14;
		break;
		default:break;
		}

	}


  P1=0xef;
  temp=P1;
  temp=temp&0x0f;
   if(temp!=0x0f)
	{

	delay_10ms();
	    switch(temp&0x0f)
		{                                                                                           


		case 0x0e:
 	    key=1;
		break;
		case 0x0d:
 	    key=5;
		break;
		case 0x0b:
 	    key=9;
		break;
	    case 0x07:
 	    key=13;
		break;
		default:break;
		}

	}


return key;


}