#include<reg51.h>
#define uchar unsigned char
#define uint unsigned int
#define dadata P0
void delay(uint xms)
{
uint i,j;
for(i=xms;i>0;i--)
for(j=110;j>0;j--);
}
void main()
{
uchar temp=255,a=1;
while(1)
{
if(a==0)
{
dadata=temp ;
delay(5);
temp--;
if(temp==255)
a=1;
}
if(a==1)
{
dadata=temp;
delay(5);
temp--;
if(temp==0)
a=0;
}
}
}
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