ADXL345各轴加速度值有较大波动

我已经帮楼主在我们这边的板子上做了测试，ADXL345+ADuC7026，测试+/-16G，串口使用9600。主要代码如下：
 
void
IRQ_Handler() __irq
{
if(0 != (IRQSTA & SPM5_IO_BIT))   //External
IRQ3 (IRQ3->INT2 pin of ADXL345)
{
  Calculate_Sign = 1;     //Set
flag
  xl345Read(6, XL345_DATAX0, buf); //Read DATAX/Y/Z
registers
  DataX_Low = buf[0];
  DataX_High = buf[1];
  DataX_High
&= 0x1F;
  DataY_Low = buf[2];
  DataY_High = buf[3];
  DataY_High
&= 0x1F;
  DataZ_Low = buf[4];
  DataZ_High = buf[5];
  DataZ_High
&= 0x1F;
}
else if(0 != (IRQSTA & UART_BIT))  //UART
Interrupt
{
  UartInterrupt = COMIID0 ;
  if(0x04 ==
UartInterrupt)   //Has Received a Data
  {
   UartDataReceived =
COMRX;  //Get Received Data
 
   if(0xAA == UartDataReceived) //Test
Communication By Sending Device ID
   {
       while(!(0x020==(COMSTA0
& 0x020))){}
     COMTX = Dev_ID;    //COMTX is an 8-bit Transmit
Register.
   }
   if(0x55 == UartDataReceived) //Start
Command
   {
    IsStart = 0x01;
   }
   if(0xA5 ==
UartDataReceived) //Stop Command
   {
    IsStart =
0x00;
   }
  }
}
}
void ADuC7026_Initiate(void)
{
   
//Clock Initial
POWKEY1 = 0x01;     //Start PLL Setting
    POWCON =
0x00;     //Set PLL Active Mode With CD = 0  CPU CLOCK DIVIDER = 41.78MHz
   
POWKEY2 = 0xF4;     //Finish PLL Setting
 
GP1CON = 0x00002211;   //PIN
set up for I2C and UART
GP2DAT = GP2DAT | 0x04040000; //Disable
LCD;
GP0DAT = GP0DAT | 0x02020000; //Disable LED;
GP4DAT = GP4DAT |
0x01000000; //Grouding the SDO, I2C address for writing and reading is 0xA6 and
0xA7
 
    //UART Initial，Baud Rate = 9600
COMCON0 = 0x080; 
 
COMDIV0 = 0x088;     
COMDIV1 = 0x000;
COMCON0 = 0x007;   
  
 
//I2C Initial
I2C1CFG = 0x00000082;        // Master Enable &
Enable Generation of Master Clock
I2C1DIV = 0x3232;          // 0x3232 =
400kHz 0xCFCF = 100kHz
 
    //Interrupt Set Up
    FIQEN =
SM_MASTER1_BIT;   //I2C1 Master Interrupt
 
}
//ADXL345 initialization,
register configuration
void ADXL345_Initiate()
{
buf[0] =
XL345_RATE_50;    //Output Data Rate: 50Hz
xl345Write(1, XL345_BW_RATE,
buf);
buf[0] = XL345_FULL_RESOLUTION | XL345_RANGE_16G;//Data Format: +/-16g
range, right justified,  256->1g
xl345Write(1, XL345_DATA_FORMAT,
buf);
buf[0] = XL345_DATAREADY;   //INT_Enable: Data Ready
xl345Write(1,
XL345_INT_ENABLE, buf);
buf[0] = XL345_DATAREADY;   //INT_Map: Data Ready
interrupt to the INT2 pin
xl345Write(1, XL345_INT_MAP, buf);
}
void
main(void)
{
ADuC7026_Initiate();    //ADuC7026
Initialization
ADXL345_Initiate();     //ADXL345 Initialization
IsStart
= 0x00;      //Variables initialization
xl345Read(1,XL345_DEVID,buf);
  //Get Device ID
Dev_ID = buf[0];
 
COMIEN0 = 0x01;      //Enable
Receive Buffer Full Interrupt    
IRQEN = UART_BIT | SPM5_IO_BIT;  //Enable
UART and IRQ3 Interrupt (IRQ3->INT2 pin of ADXL345)
 
buf[0] =
XL345_MEASURE;    //Power CTL: Measure mode
xl345Write(1, XL345_POWER_CTL,
buf);
 
while(1)
{
  if(0x01 == IsStart)     //
Start
  {
      if(1 == Calculate_Sign)
   {
    Calculate_Sign =
0;
    
    Acceleration[X_CHANNEL] =
DataX_High;
    Acceleration[X_CHANNEL] = (Acceleration[X_CHANNEL]<<8)
| DataX_Low;
 
    Acceleration[Y_CHANNEL] =
DataY_High;
    Acceleration[Y_CHANNEL] = (Acceleration[Y_CHANNEL]<<8)
| DataY_Low;
 
    Acceleration[Z_CHANNEL] =
DataZ_High;
    Acceleration[Z_CHANNEL] = (Acceleration[Z_CHANNEL]<<8)
| DataZ_Low;
    
    //Translate the twos complement to true binary
code (256+4096)->1g, (4096-256)->(-1)g           
 
    for(iTemp=X_CHANNEL;iTemp<=Z_CHANNEL;iTemp++)
    {
     if(Acceleration[iTemp]
< 4096)
     {
      Acceleration[iTemp] = Acceleration[iTemp] +
4096;
     }
     else if(Acceleration[iTemp] >=
4096)
     {
      Acceleration[iTemp] = Acceleration[iTemp] -
4096;
     }
     un.ui =
Acceleration[iTemp];
     putchar(un.uc[1]);//High
Bit
     putchar(un.uc[0]);//Low
bit
    }
   }
  }
}
}
 
得到的原始数据如下所示：
 

 
其中每两列为一轴的高低8位数据，结果与数据手册指标相符。以下三图分别为静止、沿X、Z轴晃动在PC端通过串口接收与显示的测试结果。
 

 

 

 
所以如果芯片确定是从正规渠道购买的，芯片本身是没有问题的。请再检查一下软件是否正确或SPI通信是否正常。