AD7799使用困惑，急！！

只看该作者 · 2007-4-7 15:21

我用的是AD7799BRUZ芯片，打算应用于称重。
电路连接参照数据手册(Rev.0) 27页的那个电路，
我只用了AIN1一个通道，其余未用。

出现的问题是：采不出数据。

进行满量程校准后读出的数据全为FF，读状态寄存器有错误标志。把REF_DEC置位后有NOREF错误标志，可是我的参考电压接是是正5V啊，是不是AD7799内部的参考电压电路部分损坏了啊！！
#include <intrins.h>        /* use _nop_() function */
/*
AD7799写寄存器函数
WriteData：要写的数据
*/
void WriteByteToAd7799(unsigned char WriteData)
{
   unsigned char i;
   //AD7799_CS=0;
   for(i=0;i<8;i++)
   {
      AD7799_SCLK=0;
      if(WriteData&0x80)AD7799_DIN=1;
      else AD7799_DIN=0;
      WriteData=WriteData<<1;
      AD7799_SCLK=1;
    }
    //AD7799_CS=1;
}

/*
AD7799读寄存器函数
*/
unsigned char ReadByteFromAd7799(void)
{
   unsigned char i;
   unsigned char ReadData;
   //AD7799_CS=0;
   ReadData=0;
   for(i=0;i<8;i++)
   {
      AD7799_SCLK=0;
      ReadData=ReadData<<1;
      if(AD7799_DOUT)ReadData+=1;
      AD7799_SCLK=1;
   }
   //AD7799_CS=1;
   return(ReadData);
}

void WaiteRDY(void)
{
    unsigned int iint;
    iint=0;
    while(AD7799_RDY)
    {
        iint++;
        if(iint>20000)
        {
            //reset ad7799
            WriteByteToAd7799(0xff);
            WriteByteToAd7799(0xff);
            WriteByteToAd7799(0xff);
            WriteByteToAd7799(0xff);
            for(iint=0;iint<1000;iint++)
            {
                _nop_();
                _nop_();
            }
            Ad7799_Ini(0);
            break;
        }
    }
}

void Ad7799_Ini(unsigned char ChannelNum)
{

    WriteByteToAd7799(0x10);//b0000 1000
    /* Writes to Communications Register Setting Next Operation as Write to
    CONFIGURATION Register*/
    WriteByteToAd7799(0x00); //增益为0
    WriteByteToAd7799(0x10+ChannelNum); //1通道
    /*CONFIGURATION REGISTER[00,BO(0),U/B(0),
    0(0),G2(1),G1(1),G0(1),0,0,REF_DET(0),BUF(1),0(0),CH2(0),CH1(0),CH0(0)]*/

    WriteByteToAd7799(0x08); //b0000 1000
    /* Writes to Communications Register Setting Next Operation as Write to
    Mode Register*/
    WriteByteToAd7799(0x80);
    WriteByteToAd7799(0x0a);
    /* Writes to Mode Register Initiating Internal Zero-Scale Calibration*/
    WaiteRDY();
    /* Wait for RDY pin to go low to indicate end of calibration cycle*/
    WriteByteToAd7799(0x08);
    /* Writes to Communications Register Setting Next Operation as Write to
    Mode Register*/
    WriteByteToAd7799(0xa0);
    WriteByteToAd7799(0x0a);
    /* Writes to Mode Register Initiating Internal Full-Scale Calibration*/
    WaiteRDY();
    /* Wait for RDY pin to go low to indicate end of calibration cycle*/

    WriteByteToAd7799(0x08); //b0000 1000
    /* Writes to Communications Register Setting Next Operation as Write to
    Mode Register*/
    WriteByteToAd7799(0x00);
    WriteByteToAd7799(0x0A);
    /* Mode Register[MD2(0),MD1(0),MD0(0),PSW(0),0(0),0(0),0(0),0(0),
    (0),(0),0(0),0(0),FS3(1),FS2(0),FS1(1),FS0(0)]*/
    /*模式0 Continuous-Conversion Mode.，Fadc=16.7HZ;*/
}

long ReadAd7799ConversionData(void)
{
    long ConverData;
    unsigned char ADSAT;
    unsigned int iint;

    WaiteRDY();
    WriteByteToAd7799(0x40);
    ADSAT=ReadByteFromAd7799();
    if((ADSAT&0x40)||(ADSAT& 0x08)==0)  //出错或者读写异常
    {
   WriteByteToAd7799(0xff);
   WriteByteToAd7799(0xff);
   WriteByteToAd7799(0xff);
   WriteByteToAd7799(0xff);
   for(iint=0;iint<3000;iint++)
   {
        _nop_();
    }
    Ad7799_Ini(0);
       return(0);
    }
    else
    {
    WriteByteToAd7799(0x58);

    /* Writes to Communications Register Setting Next Operation as Continuous
    Read From Data Register*/
    WaiteRDY();
   /* Wait for RDY pin to go low to indicate end of calibration cycle*/
   if(!AD7799_RDY)
   {
       ConverData=0;
       ConverData=ReadByteFromAd7799();
       ConverData=ConverData<<8;
       ConverData=ReadByteFromAd7799()+ConverData;
       ConverData=ConverData<<8;
       ConverData=ReadByteFromAd7799()+ConverData;
   }
   /* Read Conversion Result from AD7730's Data Register*/

   return(ConverData);

   }
}

#include <reg52.h>
#include "ad7799.h"

idata long addata;

main()
{
   Ad7799_Ini(0);
   while(1)
   {
     addata=ReadAd7799ConversionData();
   }
}