void AD9850_Write_Serial(unsigned char W0,unsigned long freq)
{
    unsigned char i,wdata ;
    unsigned long  y ;
    y = (unsigned long )268435456.0/AD9850_SYSTEM_COLCK*freq ;  
    
    wdata = y>>0 ;   //写w4
    for(i=0 ;i<8 ;i++)
    {
        if(wdata & 0x01)
          AD9850_DATA_Write_1 ;
        else
          AD9850_DATA_Write_0 ;
        AD9850_WCLK_SET ;
        wdata >>= 1 ;
        AD9850_WCLK_CLR ;
    }
    wdata = y>>8 ;  //写w3
     for(i=0 ;i<8 ;i++)
    {
        if(wdata & 0x01)
          AD9850_DATA_Write_1 ;
        else
          AD9850_DATA_Write_0 ;
        AD9850_WCLK_SET ;
        wdata >>= 1 ;
        AD9850_WCLK_CLR ;
    }
    wdata = y>>16 ;  //写w2
     for(i=0 ;i<8 ;i++)
    {
        if(wdata & 0x01)
          AD9850_DATA_Write_1 ;
        else
          AD9850_DATA_Write_0 ;
        AD9850_WCLK_SET ;
        wdata >>= 1 ;
        AD9850_WCLK_CLR ;
    }
    wdata = y>>24 ;  //写w1
     for(i=0 ;i<8 ;i++)
    {
        if(wdata & 0x01)
          AD9850_DATA_Write_1 ;
        else
          AD9850_DATA_Write_0 ;
        AD9850_WCLK_SET ;
        wdata >>= 1 ;
        AD9850_WCLK_CLR ;
    }
    wdata = W0 ;  //写w0
     for(i=0 ;i<8 ;i++)
    {
        if(wdata & 0x01)
          AD9850_DATA_Write_1 ;
        else
          AD9850_DATA_Write_0 ;
        AD9850_WCLK_SET ;
        wdata >>= 1 ;
        AD9850_WCLK_CLR ;
    }
    
    AD9850_FQUD_SET ;  //移入使能
    AD9850_Delay(0xFFFF) ;
    AD9850_FQUD_CLR ;
}

延时函数：

#endif /* MODE_SERIAL */

void AD9850_Delay(unsigned int z)
{
    for(;z>0;z--)
    {;}
}