#include <io8535v.h>
#define uchar unsigned char
#define uint  unsigned int

uchar Table[16]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,
                 0x7f,0x6f,0x77,0x7c,0x39,0x5e,0x79,0x71};
uchar Send_Data[]={'a','b','c','d'};
uchar Receive_Data[];
			 
void DelayMs(uint i)
{uint j;
 for(;i!=0;i--)
   {for(j=2000;j!=0;j--) {;}}
}

void Display(uchar *p)         //動態顯示函數，參數p為待顯示的數組名
{uchar i,sel=0x01;           
 for(i=0;i<4;i++)
  {PORTA=sel;                  //選通最右邊的數碼管
   PORTC=0xff-Table[p[i]];     //送字型碼
   DelayMs(1);                 //顯示延時    
   sel=sel<<1;                 //移位以顯示前一位
  }
}

void main(void)
{uchar temp,i;
 DDRA=0xff;
 DDRC=0xff;
 PORTA=0xff;
 PORTC=0x00;
 DelayMs(2000);
 PORTC=0xff;
 UBRR=51;//9600bps,8.000M,
 UCR=0x18;//RXD.TXD使能；
 for(i=0;i<4;i++)
   {while(!(USR&0x80)) 
      {Display(Receive_Data);}            //等待接收完成
    Receive_Data[i]=UDR-48;}            //接收數據
 for(i=0;i<4;i++)
   {while(!(USR&0x20)) 
      {Display(Receive_Data); }           //等待移位寄存器空；
    UDR=Send_Data[i];} 
 while(1)
   Display(Receive_Data);   
}