cs9-2.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};
//===============================
uchar a=0,b=0,c;			
//----------------------------------
uchar key_S1(void);		
uchar key_S2(void);			
void delay(uint k);			
//----------------------------------------
void main(void)				
{	uchar i;				
	while(1)				
	{						
	b= key_S1();				
	a= key_S2();			
	if(a>b)c=0x76;			
	if(a<b)c=0x38;		
	if(a==b)c=0x09;		
		for(i=0;i<50;i++)		
		{				
		P0= SEG7[a];		
		P2=0xfd;			
		delay(2);			
		P0= SEG7[b];		
		P2=0xfe;			
		delay(2);			
		P0= c;			
		P2=0xf7;			
		delay(2);			
		}				
	}					
}							
//----------------------------------------
void delay(uint k)				
{						
uint i,j;					
for(i=0;i<k;i++){				
for(j=0;j<121;j++)			
{;}}						
}						
//---------------------------------------
uchar key_S1(void)			
{static uchar x;			
P3=0xff;					
if(P3!=0xff)					
	{delay(10);				
		if(P3==0xfb)			
		{					
		x=x+1;				
		}					
	}						
if(x>9)x=0;					
return x;					
}						
//----------------------------------------
uchar key_S2(void)			
{static uchar y;			
P3=0xff;					
if(P3!=0xff)			
	{delay(10);			
		if(P3==0xf7)				
		{					
		y=y+1;					
		}					
	}						
if(y>9)y=0;					
return y;					
}