/* 功能：PC鍵盤0-9顯示，行列式按鍵鍵值顯示
   運行：在BANK3完成，啟動串口助手軟件后，在串口助手軟件發送區輸入的任意數字
         對應數字號碼會顯示在數碼管上。按任意行列按鍵，鍵值會顯示在助手接收區
*/
#include<at89x52.h>
#define BaudRate 9600L
#define uchar unsigned char  
code uchar SegCode[]={0xc0,0xF9,0xA4,0xB0,0x99,0x92,0x82,0xF8,0x80,0x90};

void UartInit()
{
	SCON = 0x50;
	TMOD = 0x20;
	PCON = 0x80;
	TH1 = TL1 = 0xfa;
	TR1 = 1;
}

uchar key()
{
	uchar kbuf,row,line;
	P2   = 0x0f;
	row  = P2;
	P2   = 0xf0;
	line = P2;
	kbuf = row+line;	
	return(kbuf);
}

void UartRec()
{	uchar rbuf;
	if(RI)
	{
		RI = 0;
		rbuf = SBUF;
		P0 = SegCode[rbuf];
		P1_3 = 1;
		P1_3 = 0;
		P0 = 0xff;
		P1_2 = 1;
		P1_2 = 0;		
	}
}

void main()
{	uchar ch;
	UartInit();
	while(1)
	{	
		ch = key();
		if(ch != 0xff)
		{
			while(key() != 0xff);      //返回值不會修改ch吧？
			SBUF = ch;
			while(TI==0);
			TI = 0;	
		}
		UartRec();
	}	
}