我直接使用寄存器按照原子大哥的流程写的，也是出现了问题。
一直卡死在红 {MOD}的那一行。
void Clock_Init(u8 PLL)
{
        unsigned char temp=0;  
        MYRCC_DeInit();                                                  //复位并配置向量表
        RCC->CR |= 0x00010000;                          //外部高速时钟使能HSEON
        while(!(RCC->CR>>17));                                //等待外部时钟就绪
       
        //RCC->CFGR=0X00000400; //APB1=DIV2;APB2=DIV1;AHB=DIV1;
        RCC->LLCFGR |= (PLL<<6);                   //设置PLL值 2~16
       
        RCC->LLCFGR |= (1<<22);                          //PLLSRC ON
        FLASH->ACR   |= 0x00000002;                                  //FLASH 2个延时周期

        RCC->CR|=0x01000000;                                  //PLLON
        while(!(RCC->CR>>25));                                //等待PLL锁定       
               RCC->CFGR|=0x00000002;                                //PLL作为系统时钟        
        while(temp!=0x02)                                     //等待PLL作为系统时钟设置成功
        {  
                temp=RCC->CFGR>>2;
                temp&=0x03;
        }   
}