//------------------------------------AD9851---------------------------------------
#include "REG51.h"
sbit M_DATA=P1^0;  
sbit M_CLK=P1^1;   
sbit M_UD=P1^2;   
sbit M_RESET=P1^3; 
unsigned int Phase_Ctrl_Word = 0x0000; 
unsigned int Order_Ctrl_Word = 0x0001;
 /*************************************************************************************/ 
void Write_AD9851(unsigned long int Freq_Ctrl_Word)	  
{
 unsigned long int mask = 0x00000001;
 unsigned int i;
 M_UD=0;  
 for(i = 0;i < 32;i++)						 //寫頻率
 {
  M_CLK=0; 
  if(Freq_Ctrl_Word & mask)
  {
   M_DATA=1;
  }
  else 
  {
   M_DATA=0;
  }
  M_CLK=1;
  mask=mask<<1;
 }
 mask = 0x0001;
 for(i = 0;i < 3;i++)			 //寫3位控制字，
 {
  M_CLK=0; 
  if(Order_Ctrl_Word & mask)
  {
   M_DATA=1;
  }
  else 
  {
   M_DATA=0;
  }
  M_CLK=1;
  mask = mask << 1;
 }

 mask = 0x0001;
 for(i = 0;i < 5;i++)			   //寫相位控制字
 {
  M_CLK=0;
  if(Phase_Ctrl_Word & mask)
  {
   M_DATA=1;
  }
  else 
  {
   M_DATA=0;
  }
  M_CLK=1;
  mask = mask << 1;
 }
 M_UD=1; 
}
/**********************************************************************************/
void Write_freq(unsigned long int freq)
{
	unsigned long int dds; 
	dds= 42.94967296*freq;				//32位=2^32/clock*f	，用的是100M的有源震蕩器
	Write_AD9851(dds);	
}
/****************************************************************************************/
   main()
{   
    M_RESET=0;						//初始化：注意，本程序用串行方式進行數據傳輸，D0，D1接高電平，D2接低電平
	M_RESET=1;						//就省去了開始要用并行方式送控制字：00000011
	M_RESET=0;
	M_CLK=0;
	M_UD=0;	
	M_CLK=1;
	M_CLK=0;
	M_UD=1; 
	M_UD=0;
	
    Write_freq(8000000);
}