实验内容：

按下图连接器件：

程序如下所示：

#include <reg52.h> 
#include <intrins.h> 
#define uchar unsigned char 
#define uint unsigned int 
sbit SDA =   P1^1; 
sbit SHIFT  =  P1^2; 
sbit ST  =  P1^0; 
#define NOP _nop_() 
uchar led[] = {0x5b,0x3f,0x3f,0x6f}; 
uchar select[] = {0x0fe,0xfd,0xfb,0xf7}; 
uchar i=0; 
void Init( ) 
{ 
      SDA = 0; 
      SHIFT = 0; 
      ST = 0; 
} 
void delay() 
{ 
     uchar jj; 
     for(jj=0;jj<200;jj++); 
     while(jj--); 
} 
void display(uchar dat) 
{ 
      uchar ii; 
      uchar sdata=dat; 
      
    for(ii=0;ii<8;ii++) 
    { 
            if(sdata&0x80) 
        SDA=1; 
           else 
        SDA = 0; 
            sdata<<=1; 
            SHIFT =0; 
            NOP; 
            NOP; 
            SHIFT = 1; 
           NOP; 
           NOP; 
      } 
      ST = 1; 
      NOP; 
      NOP; 
      ST = 0; 
} 
void main() 
{ 
      Init(); 
      while(1) 
    { 
          delay(); 
        delay(); 
          P2 = select[i]; 
          display(led[i]); 
          i=(i+1)%4; 
      } 
}