values ​​of iis3dwb mems

[Kyouk.1]

I am reading the x, y, z axis values ​​of iis3dwb mems using DSP Microprocessor.

However, the following results are displayed.

lpf or 2g, 4g, 8g, 16g change the same

I want to ask if the procedure is wrong

X auxi : red graph

initial(default) value : 39xx.xxxxxx ~ 3996.xxxxxx(mg)

Q1) How to set the initial value to 0?

Value changes rapidly even without vibration.(0g ~ 3g)

Even if there is vibration, the value changes rapidly.(0g ~ 3g)

Q2) How to make the rate of change small?

It is not a program error.

Q3) Is the sensitivity of the original iis3dwb like this?

[Kyouk.1]

The offset adjustment problem is solved.

(Solved by setting CTRL7_C register)

Thank you.

[Kyouk.1]

The offset adjustment problem is solved.

(Solved by setting CTRL7_C register)

Thank you.

[Kyouk.1]

Rather than this, the problem is that noise occurs when updating block data.

If the block data is not updated, noise does not occur.

[Kyouk.1]

Hello...​

Z-axis data fluctuates after block data update.

Look at the graph.

Block data updata enabale case (A) and block data updata disable case (B)

This is my sequence.

Are there any errors?

It seems to be the last question.

​Thank you....

​

[Eleon BORLINI · Accepted solution]

Hi @Kyouk.1​ ,

trying to answer to your

Q2) The hpf adjustment changes position, but the signal is fluctuating.

Is there another way?

Please check this thread if can be of any help for you. The suggestion here is to properly set both HP and LP2 filters.

 iis3dwb_xl_hp_path_on_out_set(&dev_ctx, IIS3DWB_HP_ODR_DIV_800);
 iis3dwb_xl_filter_lp2_set(&dev_ctx, PROPERTY_ENABLE);
 
/* Into --> */
 
iis3dwb_xl_hp_path_on_out_set(&dev_ctx, IIS3DWB_XL_ODR_26k7Hz);
iis3dwb_xl_filter_lp2_set(&dev_ctx, PROPERTY_ENABLE);

Q3) When the block data is updated, a noise signal is generated.

If the block data is not updated, the noise signal disappears.

    Is there another way?

Is it mandatory for you to have the BDU enabled?

-Eleon

[Kyouk.1]

Hello.

Thanks for the advice.

I want to set the X, Y, Z auxi to 0mg(I want to avoid gravity)

Even if I adjust hpf and lpf, it cannot be set to 0mg

[Eleon BORLINI]

Hi @Kyouk.1​ ,

it's strange that with the high pass... did you correctly configured the HPCF_XL_[2:0] and the FDS bits of CTRL8_XL (17h) register? (See datasheet, p.36)

Another way to make the residual offset zero is to use the user offset compensation method. You have to measure the residual offset in a steady state condition and then write it in the X_OFS_USR (73h), Y_OFS_USR (74h) and Z_OFS_USR (75h) registers, so that the chip automatically subtract this value to the output. You have also to set the USR_OFF_ON_OUT bit of CTRL7_C (16h) register to enable this path.

-Eleon