About Thingy52 custom firmware: I can't choose accelerometer 16G range

[manumonti]

Hi all,

I'm working with Nordic Thingy:52 (nRF6936 with nRF52832 inside).

Currently I'm working with original firmware (I mean, not modified firmware) version 2.1.0. But doing some tests with Thingy52 and nRF connect Android app, I realized that the range of the accelerometer axis is from -G (-9.81) to +G (9.81). So 9.81 is the limit even if I shake strongly the Thingy:52, and I need a higher range.

Taking a look to documentation, I see I can choose the acceleration range, so I decided to modify the firmware.

From "/NordicThingyFW/include/drivers/drv_acc_lis3dh_types.h":

/** @brief Acceleration ranges.
 */
typedef enum
{
  FULLSCALE_2             = 0x00,   ///<  2 G full scale.
  FULLSCALE_4             = 0x01,   ///<  4 G full scale.
  FULLSCALE_8             = 0x02,   ///<  8 G full scale.
  FULLSCALE_16            = 0x03    ///< 16 G full scale.
} Fullscale_t;

I'm not sure what I have to modify from firmware in order to change acceleration range, for instance, to FULLSCALE_16. I have tried unsuccessfully the following:

From "/NordicThingyFW/include/drivers/drv_acc_lis3dh_types.h", on "drv_acc_wakeup_prepare(bool wakeup)" function:

[...]
if(wakeup)
    {
        NRF_LOG_DEBUG("Configuring LIS3DH for wake on motion \r\n");

        uint8_t ctrl_regs[] = {(ODR_100Hz << 4) | CTRL_REG1_LPEN | CTRL_REG1_ZEN | CTRL_REG1_YEN, //| CTRL_REG1_XEN,  // CTRL_REG1
                                CTRL_REG2_FDS | CTRL_REG2_HP_IA1,                                                 // CTRL_REG2
                                CTRL_REG3_I1_IA1,                                                                 // CTRL_REG3
                                0,                                                                                // CTRL_REG4
                                CTRL_REG5_LIR_INT1};                                                              // CTRL_REG5
        uint8_t int1_ths[]  = {ACC_INT1_THRESHOLD,                                                                // INT1_THS
                               ACC_INT1_DURATION};                                                                // INT1_DURATION
        uint8_t int1_cfg[]  = {INT1_CFG_ZHIE | INT1_CFG_YHIE | INT1_CFG_XHIE};                                    // INT1_CFG

        err_code = lis3dh_write_regs(CTRL_REG1, ctrl_regs, (sizeof(ctrl_regs)/sizeof((ctrl_regs)[0])));
        RETURN_IF_ERROR(err_code);
[...]

I have modified CTRL_REG4 adding CTRL_REG4_FS0 and CTRL_REG4_FS1:

if(wakeup)
    {
        NRF_LOG_DEBUG("Configuring LIS3DH for wake on motion \r\n");

        uint8_t ctrl_regs[] = {(ODR_100Hz << 4) | CTRL_REG1_LPEN | CTRL_REG1_ZEN | CTRL_REG1_YEN, //| CTRL_REG1_XEN,  // CTRL_REG1
                                CTRL_REG2_FDS | CTRL_REG2_HP_IA1,                                                 // CTRL_REG2
                                CTRL_REG3_I1_IA1,                                                                 // CTRL_REG3
                                CTRL_REG4_FS1 | CTRL_REG4_FS0,                                                    // CTRL_REG4 Modified: FullScale_16
                                CTRL_REG5_LIR_INT1};                                                              // CTRL_REG5
        uint8_t int1_ths[]  = {ACC_INT1_THRESHOLD,                                                                // INT1_THS
                               ACC_INT1_DURATION};                                                                // INT1_DURATION
        uint8_t int1_cfg[]  = {INT1_CFG_ZHIE | INT1_CFG_YHIE | INT1_CFG_XHIE};                                    // INT1_CFG

        err_code = lis3dh_write_regs(CTRL_REG1, ctrl_regs, (sizeof(ctrl_regs)/sizeof((ctrl_regs)[0])));
        RETURN_IF_ERROR(err_code);

But this doesn't work. In the nRF Connect app I see the same limit in 9.81.

Any help?

Thank you,

Manuel Montenegro.

[Bjørn Kvaale]

Hi Manuel,

You are currently modifying the low power accelerometer, which is only used for waking up the Thingy device. You will need to use the other accelerometer on the Thingy device.

I am not sure that you will need to make any changes to the code itself. I do not believe there is a n accelerometer limit in the Thingy SDK either. There could be some kind of limit in the nRF Connect apps maybe. I have tested with both iOS & Android using the Thingy apps & nRF Connect for Mobile. I was also unable to get a reading higher than +9.81 or -9.81 m/s^2. Whether this is due to a limit in the app itself or whether it is difficult for me to see a value higher than the acceleration of gravity, I am not so sure.

I have tried to increase the .motion_freq_hz in the MOTION_DEFAULT_CONFIG define in m_motion.h from 10 to 100. If you combine that with using nRF Connect for Desktop, you can connect to your Thingy device, read the gravity values & download the log. The log values are unfortunately given in hexadecimal values, so you will need to figure out a way of converting the values with a script or going through the log itself to see if you can find a value greater than g. Hope that helps a bit!

Kind Regards,

Bjørn

[manumonti]

Hi, Bjørn.

I didn't know that there are two accelerometers in the device, but it makes sense.

I'm trying to see the values captured by the hardware directly (without the android app). For this, I'm trying to see debug messages, but how you can see in this post, I can't do it.

Thank you for your answers,

Manuel Montenegro.

[Bjørn Kvaale]

Did you get the logging working now? It seems that Martin answered your other question. It is a good idea to check out the logging on the device itself before trying to log via nrf connect for desktop.