Functions to Magnetometer HMC5883

Collaboration diagram for Functions to Magnetometer HMC5883:

Functions
uint8_t *	mag_read_reg (int i2c_dev, uint8_t reg, uint8_t count)
	READ COUNT 8-BIT REGISTER IN SEQUENCE. More...
int	mag_read_all_data (int i2c_dev, short int *data)
	READ ALL DATA AT ONCE (X, Y and Z) More...
short int	mag_read_data (int i2c_dev, int axis)
	READ DATA (X, Y or Z) More...

Detailed Description

Function Documentation

int mag_read_all_data	(	int	i2c_dev,
		short int *	data
	)

READ ALL DATA AT ONCE (X, Y and Z)

Parameters

	i2c_dev
[out]	*data

Definition at line 121 of file mag_functions.c.

References FAILURE, MAG_DATAX1, mag_read_reg(), and SUCCESS.

Referenced by read_all_data().

{
  uint8_t i, j;
  uint8_t *data8;
  union result
  {
    unsigned short int usgnd[3];
    short int sgnd[3];
  } result;
  //result=(union result*)malloc(3*sizeof(union result));
  if( (data8=mag_read_reg(i2c_dev,MAG_DATAX1,6))==NULL)
  {
    //perror("Read accelerometer register failed");
    return FAILURE;
  }
  //result.usgnd=(unsigned int*)malloc(3*sizeof(unsigned int));
  j=0;
  for(i=0; i<3; i++)
  {
    result.usgnd[j]=0;
    result.usgnd[j]=result.usgnd[j]|((unsigned short int)data8[i*2+1])|(((unsigned int)data8[i*2])<<8);
    data[j]=result.sgnd[j];
    j=2-i; // trick used to change the sorting of the data from XZY to XYZ
  }
  return SUCCESS;  
}

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short int mag_read_data	(	int	i2c_dev,
		int	axis
	)

READ DATA (X, Y or Z)

Parameters

i2c_dev
axis	set the axis ('X' or 'Y' or 'Z')

Definition at line 148 of file mag_functions.c.

References MAG_DATAX1, MAG_DATAY1, MAG_DATAZ1, and mag_read_reg().

{
  uint8_t *data;
  union result
  {
    unsigned int usgnd;
    int sgnd;
  }result;

  switch(axis){
    case 'X':
      data=mag_read_reg(i2c_dev,MAG_DATAX1,2);
      break;
    case 'Y':
      data=mag_read_reg(i2c_dev,MAG_DATAY1,2);
      break;
    case 'Z':
      data=mag_read_reg(i2c_dev,MAG_DATAZ1,2);
      break;
    default:
      //perror("Wrong argument for axis in mag_read_data");
      return -1;
  }
  result.usgnd=0;
  result.usgnd=result.usgnd|(((unsigned short int)data[1]))|(((unsigned short int)data[0])<<8);
  return result.sgnd;
}

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uint8_t* mag_read_reg	(	int	i2c_dev,
		uint8_t	reg,
		uint8_t	count
	)

READ COUNT 8-BIT REGISTER IN SEQUENCE.

Parameters

i2c_dev
reg
count	number of registers in sequence (1-13)

Definition at line 31 of file mag_functions.c.

Referenced by mag_read_all_data(), and mag_read_data().

{
  uint8_t data[13];
  int i;

  //data=(uint8_t*)malloc((count+1)*sizeof(data));
  
  data[0] = reg;

  if (write(i2c_dev, &data, 1) != 1) {           
        //perror("write before read");
        return NULL;
  }
  data[0] = 0;
  if (read(i2c_dev, &data, count) != count) {
        //perror("read");
        return NULL;    
  }

  return data;
}

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