大家好，请教一个问题，ADS1242芯片一直输出65535？？？

你好！ Van Yang  

我试验了，可以正确的读写寄存器，我用的51单片机，AIN0接的可调电阻，最大电压5V，MUX设置为0x08,按我的理解这样是单通道通道0，我调试了一周了，一直没出来，希望能帮帮我，下面是我的程序。

ADS1242.h

#ifndef __ADS1242_H__
#define __ADS1242_H__ 
             
#include <reg52.h>               //头文件的包含
#include <intrins.h>
#define uchar unsigned char
#define uint  unsigned int
#define ulong unsigned long
#define  _Nop()  _nop_()        //定义空指令

/*定义ADS1242的寄存器地址   */
#define ADS1242_SETUP     0x00
#define ADS1242_MUX       0x01
#define ADS1242_ACR       0x02
#define ADS1242_ODAC      0x03
#define ADS1242_DIO       0x04
#define ADS1242_DIR       0x05
#define ADS1242_IOCON     0x06
#define ADS1242_OCR0      0x07
#define ADS1242_OCR1      0x08
#define ADS1242_OCR2      0x09
#define ADS1242_FSR0      0x0a
#define ADS1242_FSR1      0x0b
#define ADS1242_FSR2      0x0c
#define ADS1242_DOR2      0x0d
#define ADS1242_DOR1      0x0e
#define ADS1242_DOR0      0x0f

/*定义ADS1242的寄存器地址   */
#define ADS1242_CMD_RDATA    0x01
#define ADS1242_CMD_RDATAC   0x03
#define ADS1242_CMD_STOPC    0x0f
#define ADS1242_CMD_RREG     0x10
#define ADS1242_CMD_WREG     0x50
#define ADS1242_CMD_SELFCAL  0xf0
#define ADS1242_CMD_SELFOCAL 0xf1
#define ADS1242_CMD_SELFGCAL 0xf2
#define ADS1242_CMD_SYSOCAL  0xf3
#define ADS1242_CMD_SYSGCAL  0xf4
#define ADS1242_CMD_WAKEUP   0xfb
#define ADS1242_CMD_DSYNC    0xfc
#define ADS1242_CMD_SLEEP    0xfd
#define ADS1242_CMD_RESET    0xfe

/*配置寄存器位*/
#define BUFFER_ON     (1<<4)          /*ACR寄存器BUFFER启用*/
#define BUFFER_OFF    (0<<4)          /*ACR寄存器BUFFER不用*/

#define RANGE_0    (0<<2)                /*配置ACR寄存器的RANGE位为0*/
#define RANGE_1    (1<<2)    /*配置ACR寄存器的RANGE位为1*/

#define SPEED_0       (0<<5)    /**/
#define SPEED_1       (1<<5)

#define DATARATE_3_75 (0x02)       /*配置ACR寄存器的Data Rate为3.75HZ*/
#define DATARATE_7_5  (0x01)    /*配置ACR寄存器的Data Rate为7.5HZ*/
#define DATARATE_15   (0x00)    /*配置ACR寄存器的Data Rate为15HZ*/

#define PGA_1         (0x00)    /*配置SETUP寄存器的PGA为1   */
#define PGA_2         (0x01)    /*配置SETUP寄存器的PGA为2   */
#define PGA_4         (0x02)    /*配置SETUP寄存器的PGA为4   */
#define PGA_8         (0x03)    /*配置SETUP寄存器的PGA为8   */
#define PGA_16        (0x04)    /*配置SETUP寄存器的PGA为16  */
#define PGA_32        (0x05)    /*配置SETUP寄存器的PGA为32  */
#define PGA_64        (0x06)    /*配置SETUP寄存器的PGA为64  */
#define PGA_128       (0x07)    /*配置SETUP寄存器的PGA为128 */

/*定义IO口*/
sbit IO_PDWN=                P1^0;
sbit IO_DRDY=                P1^1;
sbit IO_SCLK=                P1^2;
sbit IO_DOUT=                P1^3;
sbit IO_DIN=                 P1^4;
sbit IO_CS=                  P1^5;

void ADS1242Init();
/*写一个字节的数据            */
void WriteByte(uchar Dat);
/*读一个字节的数据            */
uchar ReadByte();

/*写寄存器            */
void WriteReg(uchar RegAdd,uchar RegDat);

/*读寄存器            */
uchar ReadReg(uchar RegAdd);
/*选择AD通道  */
void SelectChannel(uchar PosChannel,uchar NegChannel);
/*等待AD转换完成  */
void WaitADConComplete();
/*从DOR寄存器读取转换结果  */
ulong ReadDataFromDOR(uchar PosChannel,uchar NegChannel);
/*上电自校正*/
void SelfCalibrate();
/*供主程序调用*/
ulong ADS1242Convert(uchar PosChannel,uchar NegChannel);

#endif

ADS1242.C

#include "ads1242.h"
#include "delay.h"

void ADS1242Init()
{
  IO_PDWN = 1;
  IO_DOUT = 0;
}
/*写一个字节的数据            */
void WriteByte(uchar Dat)
{
  uchar i;
  IO_CS = 0;
  IO_SCLK = 0;
  _nop_();
  for(i=0;i<8;i++)
   {
    Dat = Dat<<1;
    IO_DIN = CY;
    IO_SCLK = 1;
    _nop_();
    _nop_();
    IO_SCLK = 0;
    _nop_(); 
   }
  IO_CS = 1;
}
/*读一个字节的数据            */
uchar ReadByte()
{
  uchar i,RDat;
  RDat = 0;
  IO_CS = 0;
  IO_SCLK = 0;
  _nop_();
  for(i=0;i<8;i++)
   {
    
    IO_SCLK = 1;
    _nop_();
    RDat = (RDat<<1)|IO_DOUT;
    IO_SCLK = 0;
    _nop_();
    _nop_();
 //   DelayUs2x(2);
   }
  IO_CS = 1;
  return RDat;
}
/*写寄存器            */
void WriteReg(uchar RegAdd,uchar RegDat)                              /*寄存器地址，写入数据*/
{
  WriteByte(ADS1242_CMD_WREG + RegAdd);                         /*写寄存器命令+寄存器地址*/
  WriteByte(0x00);
  WriteByte(RegDat);
}

/*读寄存器            */
uchar ReadReg(uchar RegAdd)                                           /*寄存器地址  */
{
  WriteByte(ADS1242_CMD_RREG + RegAdd);                         /*读寄存器命令+寄存器地址*/
  WriteByte(0x00);
  return (ReadByte());
}
/*选择AD通道  */
void SelectChannel(uchar PosChannel,uchar NegChannel)                 /*正向通道，负向通道*/
{
  WriteReg(ADS1242_MUX,((PosChannel<<4)+NegChannel));
}
/*等待AD转换完成  */
void WaitADConComplete()
{
 IO_CS = 0;
 while(!IO_DRDY);                                                   /*DRDY为0表示转换完成*/
 while(IO_DRDY);
 IO_CS = 1;
}
/*从DOR寄存器读取转换结果  */
ulong ReadDataFromDOR(uchar PosChannel,uchar NegChannel)              /*正负通道号*/
{
  ulong temp;
  uchar i;
  IO_CS = 0;
  SelectChannel(PosChannel,NegChannel);                         /*选择通道*/
  WriteByte(0x01);                                         /*发送读数据命令*/
  IO_CS = 0;
  DelayMs(1);                                              /*发送读数据命令*/
  temp = ReadByte();
    temp = (temp << 8) | ReadByte();
    temp = (temp << 8) | ReadByte();
  IO_CS = 1;
  return temp;
}
/*上电自校正*/
void SelfCalibrate()
{
  IO_PDWN = 1;
  WriteByte(ADS1242_CMD_RESET);
  WriteReg(ADS1242_SETUP,PGA_1);
  WriteReg(ADS1242_ACR,BUFFER_OFF + RANGE_0 + DATARATE_3_75);   /*配置ACR寄存器*/
        WriteReg(ADS1242_SETUP,PGA_1);
  WriteReg(ADS1242_ODAC,0x00);                                  /*上电自校正*/
  IO_CS = 0;
  while(IO_DRDY);                                               /*等待校正完成*/
  IO_CS = 1;
  WriteReg(ADS1242_ACR,BUFFER_ON + RANGE_0 + DATARATE_3_75);    /*配置ACR寄存器*/
               
}
/*供主程序调用*/
ulong ADS1242Convert(uchar PosChannel,uchar NegChannel)
{
  ulong temp;
  ADS1242Init();
  SelfCalibrate();
  temp = ReadDataFromDOR(PosChannel,NegChannel);
  temp = ReadDataFromDOR(PosChannel,NegChannel);                /*取第二个数据*/
  return temp;
}