下面这个程序为什么dat需要右移七位?,595不是高位先输入到Q7吗?为什么要写个低输入的程序
#include "reg51.h"
#include<intrins.h>
typedef unsigned int u16;
typedef unsigned char u8;
sbit SRCLK=P3^6;
sbit RCLK=P3^5;
sbit SER=P3^4;
u8 ledduan[]={0x38,0x44,0x42,0x21,0x42,0x44,0x38,0x00};
u8 ledwei[]={0x7f
,0xbf,0xdf,0xef,0xf7,0xfb,0xfd,0xfe};
void delay(u16 i)
{
while(i--);
}
void Hc595SendByte(u8 dat)
{
u8 a;
SRCLK=0;
RCLK=0;
for(a=0;a<8;a++)
{
SER=dat>>7;
dat<<=1;
SRCLK=1;
_nop_();
_nop_();
SRCLK=0;
}
RCLK=1;
_nop_();
_nop_();
RCLK=0;
}
void main()
{
u8 i;
while(1)
{
P0=0x7f;
for(i=0;i<8;i++)
{
P0=ledwei[i]; //位选
Hc595SendByte(ledduan[i]); //发送段选数据
delay(100); //延时
Hc595SendByte(0x00); //消隐
}
}
}