Question

用at89c51和74hc138 跑马灯程序

八个灯一个灯亮，其他的灭。从左往右依次亮 时间间隔50ms 单片机编程

Answer 1

sbit 74hc138_a=0x90;
sbit 74hc138_b=0x91;
sbit 74hc138_c=0x92;

while(1)
{
unsigned char n=0;
n=n-1;
n=n&0x7;
if(n&0x01)
74hc138_a=1;
else
74hc138_a=0;
if(n&0x02)
74hc138_b=1;
else
74hc138_b=0;
if(n&0x04)
74hc138_c=1;
else
74hc138_c=0;
DelaymS(50);
}
DelaymS()为毫秒级延时程序