s3c44b0x定时器5中断怎么不行？？？

大家帮我看哈，下面程序有没有错？串口没输出“test timer5”,谢谢大家
void __irq Timer5Interrupt(void)
{
  rI_ISPC= BIT_TIMER5;
  printf("test timer5\n");
}
void Timer5_Test(void)
{
 rTCFG0 = (0x13<<16)+(0x13<<8)+0x13; // pre0=19
 rTCFG1 = 0x0;  // mux=1/2
 rTCNTB5 = 3000000; //TCNTB5=3000000      
 rTCON=0x02000000; //update T5
 rTCON=0x05000000; //T5=auto reload,start 
    
 rINTCON=0x5;    //Non-vectored,IRQ enable,FIQ disable 
 rINTMOD=0x0;    //All=IRQ mode
 pISR_TIMER5 = (U32)Timer5Interrupt;
 
 rINTMSK=BIT_GLOBAL;
 rINTMSK=~(BIT_GLOBAL|BIT_TIMER5); //start timer INT
}