3.5

#include<reg52.h>


void delay(unsigned char cnt);


void main()
{
    unsigned int j;
unsigned char cnt;
    while(1)
{
  P0 = ~(0x01<<cnt);
delay(200);
cnt++;
if(cnt == 7)
{
   cnt = 1;
for(j=0;j<8;j++)
{
        P0 = ~(0x80>>j);
      delay(200);
}
//P0 = 0x00;
   //delay(200);
    //P0 = 0xFF;
    //delay(200);
}

}
}


void delay(unsigned char cnt)
{
    unsigned char i,j;
    for(i=0;i<cnt;i++)
{
       for(j=0;j<255;j++);
    }
}