#include "MSP430X16X.h"

#define  uint  unsigned int
#define  uchar unsigned char

#define SCLK_UP    P5OUT |= BIT3
#define SCLK_DOWN  P5OUT &= ~BIT3
#define SYNC_UP    P5OUT |= BIT0
#define SYNC_DOWN  P5OUT &= ~BIT0
#define SDIN_UP    P5OUT |= BIT1
#define SDIN_DOWN  P5OUT &= ~BIT1

uchar DA_ON[4]={0,0,0,1};
//uchar DA_OFF[4]={0,0,0,0};
//uchar DA_baochi[4]={0,0,1,1};

//10us¼¶ÑÓʱ×Ó³ÌÐò
void Delayus(uint us)
{
   while(us--)
     {
       for(uint i=8;i>0;i--)
         ;
     }
  }

void InitDAC(void)
{
  P5DIR=BIT0+BIT1+BIT3;
  SYNC_DOWN; 
  SDIN_UP;
  SCLK_DOWN;
}

void DAC_convert(unsigned int da)
{
  uchar i;
  SYNC_DOWN;
  SCLK_UP;

  for(i=0;i<4;i++)
  {
    SCLK_UP;
    if(DA_ON[i])
      SDIN_UP;
    else
      SDIN_DOWN;
    SCLK_DOWN;
  }
  
  for (i=0;i<12;i++)
  {
    SCLK_UP;
    if(da&0x800)
      SDIN_UP; 
    else
      SDIN_DOWN;
    SCLK_DOWN;
    da<<=1;
  }
  SDIN_UP;
  
  SYNC_UP;
  
  SCLK_DOWN;
  Delayus(10);
}