cs14-3.c

《手把手教你学单片机的C程序设计》及实验程序

#include <REG51.H>		
#define uchar unsigned char	
#define uint unsigned int	
uchar code SEG7[10]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f};
sbit P3_2=P3^2;				
//===========================
void swap(uchar *x,uchar *y);	
//===========================
void delay(uint k)				
{							
uint i,j;						
for(i=0;i<k;i++){				
for(j=0;j<121;j++)				
{;}}							
}							
//===========================
void main(void)					
{
uchar i;								
uchar a=3,b=8;					
uchar *pt1,*pt2;					
pt1=&a;							
pt2=&b;	
	while(1)			
	{					
	if(!P3_2)swap(pt1,pt2);	
		for(i=0;i<100;i++)
		{P0=SEG7[a];	
		P2=0xfd;			
 		delay(2);		
		P0=SEG7[b];	
		P2=0xfe;			
		delay(2);}
	}
}
//===========================
void swap(uchar *x,uchar *y)		
{								
uchar t;							
t=*x;							
*x=*y;							
*y=t;							
}