第4章 流水灯的实现

单片机电路图：

缓冲器、译码器电路图：

流水灯左移代码：

#include<reg52.h>
sbit ADDR0 = P1^0;
sbit ADDR1 = P1^1;
sbit ADDR2 = P1^2;
sbit ADDR3 = P1^3;
sbit ENLED = P1^4;
void main()
{
	unsigned char cnt = 0;
	unsigned int i=0;
	ENLED = 0;
	ADDR3 = 1;
	ADDR2 = 1;
	ADDR1 = 1;
	ADDR0 = 0;
	while(1)
	{
		P0 = ~(0x01 <<cnt);
		for(i=0; i<30000; i++);
		cnt++;
		if(cnt>=8)
		{
			cnt = 0;
		}
	}
}

流水灯右移代码：

#include<reg52.h>
sbit ADDR0 = P1^0;
sbit ADDR1 = P1^1;
sbit ADDR2 = P1^2;
sbit ADDR3 = P1^3;
sbit ENLED = P1^4;
void main()
{
	unsigned char cnt = 0;
	unsigned int i=0;
	ENLED = 0;
	ADDR3 = 1;
	ADDR2 = 1;
	ADDR1 = 1;
	ADDR0 = 0;
	while(1)
	{
		P0 = ~(0x80 >>cnt);
		for(i=0; i<30000; i++);
		cnt++;
		if(cnt>=8)
		{
			cnt = 0;
		}
	}
}

流水灯左移到头，然后右移，然后再左移，依次循环，代码如下：

#include <reg52.h>

sbit ADDR0 = P1^0;
sbit ADDR1 = P1^1;
sbit ADDR2 = P1^2;
sbit ADDR3 = P1^3;
sbit ENLED = P1^4;

void main()
{
    unsigned int i = 0;   
    unsigned char dir = 0; 		//0为左移，1为右移
    unsigned char shift = 0x01; 

    ENLED = 0;
    ADDR3 = 1;
    ADDR2 = 1;
    ADDR1 = 1;
    ADDR0 = 0;
    while (1)  
    {
        P0 = ~shift;             
        for (i=0; i<20000; i++);  
        if (dir == 0)            
        {
            shift = shift << 1;   
            if (shift == 0x80)    
            {
                dir = 1;
            }
        }
        else                      
        {
            shift = shift >> 1;   
            if (shift == 0x01)    
            {
                dir = 0;
            }
        }
    }
}