BNO055 heading wrong after calibration recall

[Digisolve]

Using the BNO055 I find it gives the different heading reading depending on the orientation when I power up.

I'm using NDOF (OPR MODE = 0xC0) & I've calibrated until I get 3 is all the cal status bits (CALIB_STAT = 0xFF). I then save the OFFSET & RADIUS reg to non-volatile ram (regs 0x55 thru to 0x6A). I then power the unit up point in one direction & get (say) 160 degees. I then power off, rotate thru 90 degees & power up again. I then move it back to the original direction & it read 114 degees

I staying in the same place & keeping the pitch & roll very close to 0 degees.

[BSTRobin]

Hi Digisolve，

Do you know what the surrounding magnetic field environment is like?

[Digisolve]

I have run tests outside in an open garden in daylight. There are a few houses about 20 meters away. There are no overhead power lines

The units is fully calibrated in this location & the offset & raduis data is saved. When I power the unit up & restore the cal data I heading is unreliable power up in different positions & then tun to the same point.

e.g. if I power up point in direction A i get A degrees. when I power up at 90 degres then turn to direction A I no longer get A degrees.

This is my start & calibration load functions:

#define BNO055_CAL_DATA_START   BNO055_ACCEL_OFFSET_X_LSB_ADDR
#define BNO055_CAL_DATA_SIZE    (BNO055_MAG_RADIUS_MSB_ADDR - BNO055_CAL_DATA_START + 1)

void bno055_init(void)
{
    Delay(TICK_100MS);
    
    COMPASS_RESET = 0;
    Delay(TICK_10MS);
    COMPASS_RESET = 1;
    
    Delay(7*TICK_100MS);    // wait compass POR
    
    /* switch back to page 0 */
    BNO055_I2C_Write(BNO055_PAGE_ID_ADDR, PAGE0);
    
    //    Delay(TICK_10MS);
    
    /* read chip IDs (for debug only)*/
    BNO055_I2C_Read(BNO055_CHIP_ID_ADDR);
    BNO055_I2C_Read(BNO055_ACCEL_REV_ID_ADDR);
    BNO055_I2C_Read(BNO055_MAG_REV_ID_ADDR);
    BNO055_I2C_Read(BNO055_GYRO_REV_ID_ADDR);
    BNO055_I2C_Read(BNO055_SW_REV_ID_LSB_ADDR);
    BNO055_I2C_Read(BNO055_SW_REV_ID_MSB_ADDR);
    BNO055_I2C_Read(BNO055_BL_REV_ID_ADDR);
    
    /* Wait till restart */
    while(BNO055_I2C_Read(BNO055_SELFTEST_RESULT_ADDR) != 0x0F )
    {
        Delay(TICK_10MS);
    }
    
    /* Set to config mode */
    BNO055_I2C_Write(BNO055_OPR_MODE_ADDR, BNO055_OPERATION_MODE_CONFIG);
    
    /* Set to normal power mode */
    BNO055_I2C_Write(BNO055_PWR_MODE_ADDR, BNO055_POWER_MODE_NORMAL);
    
    /* Set the output units */
    BNO055_I2C_Write(BNO055_UNIT_SEL_ADDR, 0x00); 
    
    // use external clock //
    BNO055_I2C_Write(BNO055_SYS_TRIGGER_ADDR, 0x80); 
    Delay(TICK_10MS);
    
    while(BNO055_I2C_Read(BNO055_SYS_CLK_STAT_ADDR) & 1)
    {
        Delay(TICK_10MS);
    }
    
    if((BNO055_I2C_Read(BNO055_SYS_TRIGGER_ADDR) & 0x80) == 0)
        while(1);   // !!! EXTERNAL CLOCK SELECTION FAILED
    
    /* Set the axis map (P2)*/
    BNO055_I2C_Write(BNO055_AXIS_MAP_CONFIG_ADDR, xyz_table[XYZ_MODE].map);
    BNO055_I2C_Write(BNO055_AXIS_MAP_SIGN_ADDR,   xyz_table[XYZ_MODE].sign);
    
    // Load calibration Profile //
    if(inhibit_profile == TRUE)
    {
        inhibit_profile = FALSE; 
    }
    else
    {
        BNO055_Load_Calibration_Profile();    
    }
    
    /* Set the requested operating mode (see section 3.3) */
    BNO055_I2C_Write(BNO055_OPR_MODE_ADDR, OPERATION_MODE);
    Delay(TICK_10MS);
}

void BNO055_Load_Calibration_Profile(void)
{  
    S16 profile_data[sizeof(NvBuff.CompassProfile)/sizeof(NvBuff.CompassProfile[0])];
    U8 flash_loop ;
    
    for(flash_loop = 0; flash_loop < sizeof(profile_data)/sizeof(profile_data[0]); flash_loop++)
    {    
        profile_data[flash_loop] = NvBuff.CompassProfile[flash_loop];
    }
    
    BNO055_I2C_Write(BNO055_OPR_MODE_ADDR, BNO055_OPERATION_MODE_CONFIG);
    Delay(TICK_10MS);

    BNO055_I2C_WriteArray(BNO055_CAL_DATA_START, (U8*)profile_data, sizeof(profile_data));
    
    BNO055_I2C_Write(BNO055_OPR_MODE_ADDR, OPERATION_MODE);
    Delay(TICK_10MS);
}

[Digisolve]

Please can I get some feedback. My client is chasing me daily. Thank you

[BSTRobin]

Hi Digisolve，

After you call BNO055_Load_Calibration_Profile(), you need to wait calibration status to reach 3.