这个程序为什么在中断里占空比不正确，在MAIN里就正确呢

#include

sbit PWMOUT = P0^0;

unsigned char HighRH = 0;

unsigned char HighRL = 0;

unsigned char LowRH = 0;

unsigned char LowRL = 0;

void ConfigPWM(unsigned int fr, unsigned char dc);

void ClosePWM();void init_uart(void);

void main()

{   

 unsigned int i;   

unsigned char tmp1;

    EA = 1;     //开总中断   

init_uart();   

while (1) ;

// {

//   ConfigPWM(500, 50);               //频率100Hz，占空比10%

//     for (i=0; i<40000; i++);

//  ConfigPWM(892.85, 80);              

//频率100Hz，占空比10%

//     for (i=0; i<40000; i++);

 // 

// }}void ConfigPWM(unsigned int fr, unsigned char dc)

{ 

unsigned long tmp; unsigned int high, low;

 tmp = 11059200/12/fr;

 high = (tmp*dc)/100;

 low = tmp - high; high = 65536 - high + 12;

 low = 65536 - low + 12; 

HighRH = (unsigned char)(high >>8); 

HighRL = (unsigned char)high;

 LowRH = (unsigned char)(low >> 8);

 LowRL = (unsigned char)low; 

TMOD &= 0xF0; TMOD |= 0x01; 

TH0 = HighRH;

 TL0 = HighRL; 

ET0 = 1; 

TR0 = 1; 

PWMOUT = 1; 

}

void ClosePWM()

{ 

TR0 = 0;

 ET0 = 0; 

PWMOUT = 1;

}

void InterruptTimer0() interrupt 1

{   

 if (PWMOUT == 1)  //当前输出为高电平时，装载低电平值并输出低电平 

   {       

TH0 = LowRH;       

TL0 = LowRL;       

PWMOUT = 0;   

 }    else              //当前输出为低电平时，装载高电平值并输出高电平   

 {        TH0 = HighRH;       

TL0 = HighRL;       

 PWMOUT = 1;   

}

}

void init_uart(void)

{       SCON=0x50;        //REN=1允许串行接受状态，串口工作模式2          

  TMOD= 0x00;       //定时器1为模式0（16位自动重载）                

   AUXR=0X40;   //开启1T模式      

TL1=(65535-(11059200/4/9600));    //设置波特率重装值   

TH1=(65535-(11059200/4/9600))>>8;   

TR1  = 1;        //开启定时器1    

 ES   = 1;        //开串口中断  

  }

void uart_int(void) interrupt 4 using 1

{  

unsigned char tmp1;

 unsigned int i;   

 if (RI)  

  {      

 tmp1 = SBUF;  

  if(tmp1==0x8A)       //收到的数据为0x15  

  {            

  RI = 0;     

   ES= 0;          //关闭串口中断   

   ConfigPWM(500, 50);               //频率100Hz，占空比10%     

   for (i=0; i<40000; i++);     //ES= 1;  

  }   

 else if(tmp1==0x8B)   

 {            

  RI = 0;       

 ES= 0;          //关闭串口中断     

 ConfigPWM(892.85, 80);               //频率100Hz，占空比10%     

   for (i=0; i<40000; i++);    // ES= 1;  

  }   

 }

}