ADXL345测试笔记

1、与测试装置连接：

2、测试代码：

//Add the SPI library so we can communicate with the ADXL345 sensor

#include <SPI.h>

//Assign the Chip Select signal to pin 10.

int CS=10;

//This is a list of some of the registers available on the ADXL345.

//To learn more about these and the rest of the registers on the ADXL345, read the datasheet!

char POWER_CTL = 0x2D;    //Power Control Register

char DATA_FORMAT = 0x31;

char DATAX0 = 0x32;    //X-Axis Data 0

char DATAX1 = 0x33;    //X-Axis Data 1

char DATAY0 = 0x34;    //Y-Axis Data 0

char DATAY1 = 0x35;    //Y-Axis Data 1

char DATAZ0 = 0x36;    //Z-Axis Data 0

char DATAZ1 = 0x37;    //Z-Axis Data 1

//This buffer will hold values read from the ADXL345 registers.

char values[10];

//These variables will be used to hold the x,y and z axis accelerometer values.

int x,y,z;

void setup(){

  //Initiate an SPI communication instance.

  SPI.begin();

  //Configure the SPI connection for the ADXL345.

  SPI.setDataMode(SPI_MODE3);

  //Create a serial connection to display the data on the terminal.

  Serial.begin(9600);

  //Set up the Chip Select pin to be an output from the Arduino.

  pinMode(CS, OUTPUT);

  //Before communication starts, the Chip Select pin needs to be set high.

  digitalWrite(CS, HIGH);

  //Put the ADXL345 into +/- 4G range by writing the value 0x01 to the DATA_FORMAT register.

  writeRegister(DATA_FORMAT, 0x01);

  //Put the ADXL345 into Measurement Mode by writing 0x08 to the POWER_CTL register.

  writeRegister(POWER_CTL, 0x08);  //Measurement mode 

}

void loop(){

  //Reading 6 bytes of data starting at register DATAX0 will retrieve the x,y and z acceleration values from the ADXL345.

  //The results of the read operation will get stored to the values[] buffer.

  readRegister(DATAX0, 6, values);

  //The ADXL345 gives 10-bit acceleration values, but they are stored as bytes (8-bits). To get the full value, two bytes must be combined for each axis.

  //The X value is stored in values[0] and values[1].

  x = ((int)values[1]<<8)|(int)values[0];

  //The Y value is stored in values[2] and values[3].

  y = ((int)values[3]<<8)|(int)values[2];

  //The Z value is stored in values[4] and values[5].

  z = ((int)values[5]<<8)|(int)values[4];

  //Print the results to the terminal.

  Serial.print(x, DEC);

  Serial.print(',');

  Serial.print(y, DEC);

  Serial.print(',');

  Serial.println(z, DEC);     

  delay(10);

}

//This function will write a value to a register on the ADXL345.

//Parameters:

//  char registerAddress - The register to write a value to

//  char value - The value to be written to the specified register.

void writeRegister(char registerAddress, char value){

  //Set Chip Select pin low to signal the beginning of an SPI packet.

  digitalWrite(CS, LOW);

  //Transfer the register address over SPI.

  SPI.transfer(registerAddress);

  //Transfer the desired register value over SPI.

  SPI.transfer(value);

  //Set the Chip Select pin high to signal the end of an SPI packet.

  digitalWrite(CS, HIGH);

}

//This function will read a certain number of registers starting from a specified address and store their values in a buffer.

//Parameters:

//  char registerAddress - The register addresse to start the read sequence from.

//  int numBytes - The number of registers that should be read.

//  char * values - A pointer to a buffer where the results of the operation should be stored.

void readRegister(char registerAddress, int numBytes, char * values){

  //Since we're performing a read operation, the most significant bit of the register address should be set.

  char address = 0x80 | registerAddress;

  //If we're doing a multi-byte read, bit 6 needs to be set as well.

  if(numBytes > 1)address = address | 0x40;

  //Set the Chip select pin low to start an SPI packet.

  digitalWrite(CS, LOW);

  //Transfer the starting register address that needs to be read.

  SPI.transfer(address);

  //Continue to read registers until we've read the number specified, storing the results to the input buffer.

  for(int i=0; i<numBytes; i++){

    values[i] = SPI.transfer(0x00);

  }

  //Set the Chips Select pin high to end the SPI packet.

  digitalWrite(CS, HIGH);

}

将以上代码复制到arduino IDE，并下载到arduino 控制板中。 

3、 数据的读取与判断：

水平放置状态： 

左右翻转90度： 

左右翻转90度X轴读书会发生较大变化。

前后翻转90度：  

前后翻转90度Y轴读书发生较大变化。

上下翻转180度： 

上下翻转180度Z轴读书发生较大变化。

另外在沿着X轴方向水平用力晃动时，X轴数据发生较大变化，而其它两个轴变化较小：

沿着Y轴方向水平用力晃动，Y轴数据发生较大变化，而其它两个轴变化较小：

沿着Z轴上下垂直用力晃动，Z轴数据发生较大变化，而其它两个轴变化较小：