Does Lis3dh need do calibration at when SMT in factory to our system ?

[YGary]

Hi,

from Data sheet, i saw section 3.5, it says no need to further calibration

but when i check output data from register 28-2D, the value is variety time to time ,

it has variety range for +- 20 ~ +-40, is it correct? or we should do calibration at factory side?

regards

Gary

[Miroslav BATEK]

What is the unit of mentioned variance? mg? LSB?

In any case some variance is normal, the sensor has a noise, a noise can be also induced by not completely stable environment.

Additional calibration is not needed.

[YGary]

Hi

thanks for reply, i guess the unit should be mg

output_x = (value from register 28-29) * sensitivity

the sensitivity is define as "#define SENSITIVITY_2G 1 /** mg/LSB */"

i also do some calculate with sqrt(output_x^2 + output_y^2 + output_z^2)

the variance is still.

am i go wrong with definition or something else?

regards

Gary

[Miroslav BATEK]

The sensor has several modes and according to the mode the output is 8, 10 or 12 bit left adjusted in the output 16 bit register. So you have to shift right the value in output register.

You can check your conversion is correct if you see 1g of the gravity in an axis pointing to ground.

[YGary]

Hi,

my setting is 10 bit with normal mode, with FS = +-2g, ODR = 100Hz

and i've measure for 5 minutes with 5 times, the average of conversion is 1010 mg, point to ground

regards

Gary

[Miroslav BATEK]

OK, it looks good.