LIS12DH12TR self test values

[orhan ocak]

Posted on December 18, 2017 at 15:26

Hi,  I am using LIS2DH12TR accelerometer. I am testing self test values.

When self test mode is disabled, the axis values:

Ax:100

By:80

Cz:90

When self test mode is enabled in self test mode 1,

the axis values

:

Kx:120

Ly:95

Mz:80

Kx > Ax , Ly > By but  Mz < Cz 

Can this happen on a robust accelerometer?

if Kx

 

>

Ax and  Ly

>

 By, 

the Mz value must be big than 

Cz . Is it true?

Best Regards

[Miroslav BATEK]

Posted on December 19, 2017 at 19:54

In principle it can happen and it is OK, absolute value of the difference sefl_test_on - self_test_off should be evaluated.

But what is the unit of Ax, By, Cz, Kx, Ly, Mz? Is it LSB?

The self-test should be done with FS = 2g and Normal mode (10-bit representation).

[orhan ocak]

Posted on December 20, 2017 at 08:31

Thanks Miroslav for your answer.

The unit of axes values is LSB  the above and the following measures.

When enabled self test mode 1, axes values: (FS = 2g and Normal mode (10-bit representation). CTRL_REG4: 0x84)

x:429 y:457 z:331

When disabled self test mode, axes values:

x:532 y:555 z:264

x and y values increased, z value decreased. Is it Ok?

[Miroslav BATEK]

Posted on December 20, 2017 at 10:40

It is OK if x and y values increased, z value decreased.

As I mentioned before the absolute value of the difference should be evaluated and compered with the limits mentioned in datasheet (see page 11 of the datasheet).

The value without self-test seems strange to me because I don't see the gravity in any axis and even the size of the vector is significantly less than 1g.