LIS2DW12 removing gravity

[Msaga.1]

Hello, I have read in the "application notes" that :

The LIS2DW12 provides an embedded high-pass filtering capability to easily delete the DC component of the measured acceleration (pg 12) .

can you elaborate please? does that mean we can make so the readings will be without the 1g add-up, and (theoretically) in rest we will get x=0 y=0 z=0 ?

Thank you

[niccolò]

Hi @Msaga.1​ ,

yes, with the High Pass filter you can cut the continuous earth gravity and see only the vibrations you apply on the sensor.

the readings in a rest state should be 0, but environmental noise will always keep that value different from 0.

It is to be noted that stable accelerations are not detected when the HP filter is enabled.

hope this clarifies the application note.

Niccolò

[Msaga.1]

@niccolo.ruffini​  HI , thank you , can you reference me to how to disable the DC component?

[niccolò]

Hi @Msaga.1​ ,

to disable the DC component, you need to enable the HP filter.

this is done using the BW_FILT[1:0] bits and FDS bit in CTRL6 (25h) as stated in the datasheet on page 21.

FDS = 1 for HP filter and you can choose the cut frequency through BW_FILT.

hope this helps

Niccolò

[Msaga.1]

Hi @niccolo.ruffini​  , thank you. But now I dont understand - any activation of the HP filter will disable the DC component? ie - if I activate the HP filter without choosing the cut frequency, is the DC component is disabled?

and what do you mean by "choose the cut frequency".

[niccolò]

Hi @Msaga.1​ ,

yes, every HP filter cuts the DC component.

I suggest to check what the cutoff frequency is, to choose the right one for your goal.

as the datasheet explains, you can choose the cutoff frequency with the  BW_FILT[1:0] bits

Niccolò

[Msaga.1]

Hi @niccolo.ruffini​ 

If I disable the DC component, will it affect the orientation bit? (if all will be 0 on rest, how will I know the orientation?)

and will it affect any other data we get from the accelorometer?

[niccolò]

Hi @Msaga.1​ ,

the HP filter should have effect before the signal, as per the filter diagram in the datasheet.

so you can't know the orientation with the HP filter enabled.

you can try to check on your device, maybe I'm forgetting something and you can find it out yourself.

hope this helps

Niccolò