Lim Sew Hyong

Zstar3 sensor PC application: calibration

Discussion created by Lim Sew Hyong on Jul 6, 2012

Hi,

 

I have a MMA7455L sensor board and USB stick. I am developing c# PC application with zstarlib.dll and I never change the software of the MMA7455L sensor board.

 

After AutoCalibrateAll() is called from PC side, I don't understand why the X and Y axis are calibrated to 0g, but Z-axis is calibrated to 1g?

 

theZStar.AutoCalibrateAll();

 

When I received the sensor real acceleration data through USB Stick, do I need to re-calculate the Z data like explained in AN3447?

 

For the Simple 0g X, 0g Y, +1g Z calibration technique a slightly different calculation is required for the Z axis which has recorded the CZOFF value at +1g. The sensitivity ‘S’ must therefore be subtracted from CZOFF in the calculation.

For the Z Case:
            AMEAS = [CA- (CZOFF-S)] ⁄ S

 

Please advice.

Thank you.

 

Best Regards,

SewHyong

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