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Fix BMM150 blocking magnetometer read #50

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Merged
bjornhbengtsson merged 2 commits into from
Jul 19, 2026
Merged

Fix BMM150 blocking magnetometer read #50

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b0f00a5
Fix BMM150 blocking magnetometer read
bjornhbengtsson Jul 19, 2026
b9feeed
Address BMM150 read review comments
bjornhbengtsson Jul 19, 2026
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87 changes: 49 additions & 38 deletions imu/imu.c
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Original file line number Diff line number Diff line change
Expand Up @@ -504,8 +504,8 @@ return IMU_OK;
* imu_get_mag_xyz *
* *
* DESCRIPTION: *
* Return the pointer to structure that updates the x,y,z magnetometer *
* values from the IMU *
* Return the pointer to structure that updates the x, y, z, and RHALL *
* magnetometer values from the BMM150. *
* *
*******************************************************************************/
IMU_STATUS imu_get_mag_xyz
Expand All @@ -516,52 +516,63 @@ IMU_STATUS imu_get_mag_xyz
/*------------------------------------------------------------------------------
Local variables
------------------------------------------------------------------------------*/
uint8_t regMag[6]; /* Magnetometer register bytes */
uint16_t mag_x_raw; /* Raw magnetometer sensor readouts */
uint16_t mag_y_raw;
uint16_t mag_z_raw;
IMU_STATUS imu_status; /* IMU status return codes */
uint8_t regMag[8]; /* Magnetometer register bytes */
int16_t mag_x_raw; /* Raw magnetometer sensor readouts */
int16_t mag_y_raw;
int16_t mag_z_raw;
uint16_t mag_hall_raw;
IMU_STATUS imu_status; /* IMU status return codes */


/*------------------------------------------------------------------------------
API function implementation
------------------------------------------------------------------------------*/

/* Read MAG_X, MAG_Y, MAG_Z high byte and low byte registers */
#if defined( A0002_REV1 )
imu_status = read_mag_regs( IMU_REG_MAG_XOUT_H,
&regMag[0] ,
sizeof( regMag ) );
#elif defined( A0002_REV2 )
imu_status = read_mag_regs( MAG_REG_DATAX_L,
&regMag[0] ,
sizeof( regMag ) );
#endif
/* Read BMM150 X, Y, Z, and RHALL registers */
imu_status = read_mag_regs( MAG_REG_DATAX_L,
&regMag[0],
sizeof( regMag ) );

/* Check for HAL IMU error */
if ( imu_status == IMU_TIMEOUT )
{
return IMU_TIMEOUT;
}
/* Check for magnetometer read error */
if ( imu_status != IMU_OK )
{
return imu_status;
}

/* Combine high byte and low byte to 16 bit data */
#if defined( A0002_REV1 )
mag_x_raw = ( (uint16_t) regMag[1] ) << 8 | regMag[0];
mag_y_raw = ( (uint16_t) regMag[3] ) << 8 | regMag[2];
mag_z_raw = ( (uint16_t) regMag[5] ) << 8 | regMag[4];
#elif defined( A0002_REV2 )
mag_x_raw = ( (uint16_t) regMag[1] << MAG_XY_MSB_BITSHIFT ) |
( ( (uint16_t) regMag[0] && MAG_XY_LSB_BITMASK ) >> MAG_XY_LSB_BITSHIFT );
mag_y_raw = ( (uint16_t) regMag[3] << MAG_XY_MSB_BITSHIFT ) |
( ( (uint16_t) regMag[2] && MAG_XY_LSB_BITMASK ) >> MAG_XY_LSB_BITSHIFT );
mag_z_raw = ( (uint16_t) regMag[5] << MAG_Z_MSB_BITSHIFT ) |
( ( (uint16_t) regMag[4] && MAG_Z_LSB_BITMASK ) >> MAG_Z_LSB_BITSHIFT );
#endif
/* Combine and scale the packed BMM150 register values */
mag_x_raw = (int16_t)( (uint16_t) regMag[1] << MAG_XY_MSB_BITSHIFT ) |
( ( (uint16_t) regMag[0] & MAG_XY_LSB_BITMASK ) >> MAG_XY_LSB_BITSHIFT );

mag_y_raw = (int16_t)( (uint16_t) regMag[3] << MAG_XY_MSB_BITSHIFT ) |
( ( (uint16_t) regMag[2] & MAG_XY_LSB_BITMASK ) >> MAG_XY_LSB_BITSHIFT );

mag_z_raw = (int16_t)( (uint16_t) regMag[5] << MAG_Z_MSB_BITSHIFT ) |
( ( (uint16_t) regMag[4] & MAG_Z_LSB_BITMASK ) >> MAG_Z_LSB_BITSHIFT );

mag_hall_raw = (uint16_t)( (uint16_t) regMag[7] << MAG_RHALL_MSB_BITSHIFT ) |
( ( (uint16_t) regMag[6] & MAG_RHALL_LSB_BITMASK ) >> MAG_RHALL_LSB_BITSHIFT );

/* Sign-extend the packed 13-bit X/Y and 15-bit Z measurements */
if ( mag_x_raw & ( 1 << 12 ) )
{
mag_x_raw |= (int16_t) ~( ( 1 << 13 ) - 1 );
}

if ( mag_y_raw & ( 1 << 12 ) )
{
mag_y_raw |= (int16_t) ~( ( 1 << 13 ) - 1 );
}

if ( mag_z_raw & ( 1 << 14 ) )
{
mag_z_raw |= (int16_t) ~( ( 1 << 15 ) - 1 );
}

/* Export sensor data */
pIMU->mag_x = mag_x_raw;
pIMU->mag_y = mag_y_raw;
pIMU->mag_z = mag_z_raw;
pIMU->mag_x = mag_x_raw;
pIMU->mag_y = mag_y_raw;
pIMU->mag_z = mag_z_raw;
pIMU->mag_hall = mag_hall_raw;

return IMU_OK;
} /* imu_get_mag_xyz */
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