3 axis Accelerometer ADXL345

hi, gotten 9dof imu sensor stick sparkfun includes adxl345 accelerometer, itg-3200 mems gyroscope , hmc5883l magnetometer.

i decided test on accelerometer first. i've connected 4.7k resistor ohms both sda , scl. input voltage 3v of arduino micro.


here adxl345 accelerometer code internet:

code: [select]


#include <adafruit_sensor.h>
#include <wire.h>


#define adxl345_address (0x53)        
#define adxl345_register_xlsb (0x32)
#define adxl_power_ctl (0x2d)
#define adxl_pwrctl_measure (1 << 3)

int accelerometer_data[3];

char c;

void setup()
{
  wire.begin();
  serial.begin(9600);
  
   for(int = 0; < 3; ++i)
   {
    accelerometer_data[i] = 0;
   }
  
   init_adxl345();
}

void loop() {
  read_adxl345();
  
   serial.print("accel: ");
   serial.print(accelerometer_data[0]);      // x-axis
   serial.print("\t");                      
   serial.print(accelerometer_data[1]);      // y-axis
   serial.print("\t");
   serial.print(accelerometer_data[2]);      // z-axis
   serial.print("\n");
  
   delay(500);
}

void init_adxl345()
{
  byte data = 0;

  i2c_write(adxl345_address, adxl_power_ctl, adxl_pwrctl_measure);

  i2c_read(adxl345_address, adxl_power_ctl, 1, &data);
  serial.println((unsigned int)data);
}

void i2c_write(int address, byte reg, byte data) {
  wire.begintransmission(0x53);
  wire.write(reg);
  wire.write(data);
  wire.endtransmission();
}

void i2c_read(int address, byte reg, int count, byte* data) {
 int = 0;

 wire.begintransmission(0x53);
 wire.write(reg);
 wire.endtransmission();
 wire.begintransmission(0x53);
 wire.requestfrom(0x53,count);
 while(wire.available()){
   c = wire.read();
   data[i] = c;
   i++;
 }
 wire.endtransmission();
}

void read_adxl345()
{
 byte bytes[6];
 memset(bytes,0,6);

 i2c_read(adxl345_address, adxl345_register_xlsb, 6, bytes);

 for (int i=0;i<3;++i)
 {
   accelerometer_data[i] = (int)bytes[2*i] + (((int)bytes[2*i + 1]) << 8);
 }
}



my display output, getting:
x: 0      y: 5           z: 264

my 'x' remains @ 1, 0 or -1
my y remains around 5,6,7 values
my z remains around  263, 264

all these values when board resting on horizontal surface. understand should display of 0,0,1 x, y, z values respectively.. no. because should convert unit?

im not quite sure how check accuracy of values displayed.. there method check?
and how conversion of units bytes unit, g ?

please help, , thank in advance!

no, because sitting on desk adxl345 subject 1g field of earth. if flip upside down, z values should go negative. if put on side x or y show 263-264.

the accelerometer can calibrated high precision clever algorithms or can subtract offset , multiply "g per lsb" shown in datasheet.

depending on want do, may or may not make sense remove 1g constant.

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