#include <reg51.h>
#include <absacc.h>
#include <math.h>
sbit B_AB = P1^7;
sbit CS = P1^0;       //P1^4;    P1^0;
sbit READY = P1^1;    //P3^2     P1^1;
sbit SCLK = P1^4;     //P1.7     P1^4;
sbit DIN = P1^3;      //P1^6     P1^3;
sbit DOUT = P1^2;     //P1.5     P1^2;
signed int s = 0;

void exint0_ist(void) interrupt 0 using 0
{
if (B_AB)
  s = s+1;
  else s=s-1;
}

//寫7731函數，寫入一個字節，如寫入多個字節，重復該函數。
void print_led(int cord,int i)
{
short bcd,p1_bcd;
if (i==1)
  {
  bcd=cord/1000;
  bcd=bcd<<4;
  p1_bcd=bcd+0x0e;
  P3=p1_bcd;
   }
if (i==2)
   {
  cord=cord%1000;
  bcd=cord/100;
  bcd=bcd<<4;
  p1_bcd=bcd+0x0d;
  P3=p1_bcd;
   }
 if (i==3)
 {
  cord=cord%100;
  bcd=cord/10;
  bcd=bcd<<4;
  p1_bcd=bcd+0x0b;
  P3=p1_bcd;
  }
 if (i==4)
 {
  cord=cord%10;
  bcd=cord/1;
  bcd=bcd<<4;
  p1_bcd=bcd+0x07;
  P3=p1_bcd;
  }
}

void write7731(short val)
{short temp,i;
  temp = val;
  for (i=0;i<8;i++)
  {
  temp = temp & 0x80;
  if (temp == 0x80)
       DIN = 1;
       else
       DIN = 0;
  temp = val; temp = temp<<1; val=temp;
  SCLK = 0;
  SCLK = 1;
  }
}

//讀7731函數,每次讀取一個字節。
short read7731(void)
{
 short i,temp=0;
 for (i=0;i<8;i++)
 {
 SCLK = 0;
 SCLK = 1;
 temp = temp << 1;
if (DOUT)
    temp = temp | 0x01;
    else
    temp=temp | 0x00;
 }
 return(temp);
}

//  AD7731 初始化。
void int7731(void)
{
int i;
i=0;
while(i<10) i=i+1;
 CS = 0;
 write7731(0x03); //設置濾波器，輸出速率為50Hz 。
 write7731(0x13);
 write7731(0x34);
 write7731(0x02); //滿量程校準。
 write7731(0xa1);
 write7731(0xf4);
 while(READY);
 write7731(0x02); //零刻度校準。
 write7731(0x81);
 write7731(0xf4);
 while(READY);
 CS = 1;
}

//初始化成連續讀取24位轉換數據。
void int_continuous_conversion(void)
{
 CS = 0;
 write7731(0x02);
 write7731(0x21);
 write7731(0xf4);
 while(READY);
 DIN = 0;
 CS = 1;
}
//單次讀取24位轉換數據。
long single_conversion(void)
{
unsigned short f1, f2,f3;
unsigned long f;
 CS=0;
 write7731(0x02);
 write7731(0x41);
 write7731(0xf4);
 while (READY);
 write7731(0x11);
 f1=read7731();
 f2=read7731();
 f3=read7731();
 f=0;
 f=f1*256;
 f=256*(f+f2);
 f=f+f3;
 CS=1;
 return (f);
}
void main(void)
{
unsigned short a, b,c,i;
unsigned long x;
biaozhi();
int7731();
int_continuous_conversion();
IT0=1;
EX0=1;
EA=1;
CS = 0;
while(1)
{
 while(!READY)
{
 if (i>4) i=1;
 write7731(0x11);
 a=read7731();
 b=read7731();
 c=read7731();
 x=0;
 x=a*256;
 x=256*(x+b);
 x=x+c;
 i=i+1;
 }
}
CS=1;
}