How to test offset calibration using MMA8451Q

[chetanveer]

Hi,

How to test offset calibration with different scenario and how to confirm expected accelerometer output. we test offset calibaretion on flat surface and read expected output. we want to test and confirm with different condition. please share information.

Thank you,

[TomasVaverka]

Hi Chetan,

The following Freescale application notes describe different methods of final accelerometer recalibration.

AN4069 - Offset Calibration of the MMA8451, 2, 3Q:

http://cache.freescale.com/files/sensors/doc/app_note/AN4069.pdf

AN4399 - High Precision Calibration of a Three-Axis Accelerometer:

http://cache.freescale.com/files/sensors/doc/app_note/AN4399.pdf​

Hope it helps.

Regards,

Tomas

PS: If my answer helps to solve your question, please mark it as "Correct". Thank you.

[deshvirmalik]

Hi Tomas,

Thank you very much for this information. This really helped us in solving our problem.

I have one more doubt related to recalibration, we have gone through the datasheet "AN4069". In the datasheet, it is mentioned "Recalibration after the sensor has been PCB-mounted may be needed for other reasons as well. For example, an application may need to change the zero (0) reference point if the zero (0) position in a tilt application is always at a 15° angle, thus considering this the new “zero” position. These recalibrations add to the end product manufacturing cost (by adding additional steps to assembly). Accordingly, the benefit of recalibration will have to be weighed against these added costs."

Test Scenerio:

If we keep accelerometer sensor at a 15° angle and perform the recalibration.

Are we supposed to get  x=0 ,y=0 and z=1?

If yes, we are not getting same value as x=0 ,y=0 and z=1.

Hence, I request you to help us on how to recalibrate in such cases. If you have any related datasheet, please forward the link along with the software flowchart for the recalibration.

Regards,

Deshvir