还不是很懂，给点建议
#include <reg52.h>
typedef unsigned char uchar;
#define Ton 50
#define LED P0

unsigned char Maikuan=0;
uchar Occupy_led;     //占空比越大，灯越亮
bit light;
uchar m;

void Inittime()                 //初始化函数
{
TMOD = 0x02; //定时器0，工作方式2，自动重装
TH0 = 256-Ton;
TL0 = 256-Ton;
ET0 = 1;
EA = 1;
TR0 = 1;
}                   //定时器0中断

void time0() interrupt 1 using 0
{
   Maikuan++;
}

void main()
{
Inittime();
while (1)
{
//所有的灯逐渐从暗到全亮，再由全亮到暗
for (m=254; m>0; m--)
{
  while (Maikuan!=Occupy_led)
  {
   LED = 0x00;           //亮
  }

  while (Maikuan!=127)
  {
   LED = 0xff;           //灭
  }
Maikuan = 0;
  if (light)
  {
    Occupy_led++;
  }
  else
  {
    Occupy_led--;
  }

  if (Occupy_led==128)
  {
    Occupy_led = 127;
    light = !light;
  }
  if (Occupy_led>128)
   {
    Occupy_led = 0;
    light = !light;
   }
  }
   
}
}