关于计时器中断问题

请问一下,我要用2440的tim0去做计时中断每1秒中断一次程序码如下好像无法做到1秒
void  __irq Timer0_ISR(void)  
{  
   rSRCPND=1<<rINTOFFSET;
    rINTPND = rINTPND;  
    
}  


void TimeInit(void)  
{  
      
    
        rTCFG0 =249;        // prescaler等于249

            
          rTCFG1 =0x02;     //
           rTCNTB0 = 25000;  //
        
       rTCMPB0 = 0; // 50%  即占空比
      
            
           rTCON |=(1<<1);//        
                          rTCON =0x09 ;  //
    

}  

void irq_init()  //中断初始化
{
  
  
  
    rINTMSK = ~(0x1<<10);
       rINTMOD=0;

}

void main()


{

MMU_Init();//

TimeInit();
irq_init();
pISR_TIMER0 = (unsigned int) Timer0_ISR;//    


}