ADXL375 offset register/Shock Threshold

[Vindhyachal.takniki]

1. I have to write offset register values in adxl375.
On putting device so that x = 0g , y = 0g & z = 1g
I get output valuesfrom adxl375 as; xreg = -14 , yreg = 15 & zreg = +34


Now what should I write to offset registers of adxl375;
a). Is it invert of each value

b). I read AN-1077 describing offset regsiter value of adxl345, it had mention values as
X_CALIB = –(OUTPUT (X) ÷ 4)
Y_CALIB = –(OUTPUT (Y) ÷ 4)
Z_CALIB = –((OUTPUT (Z) – 256) ÷ 4)

c). which of above I should choose







2. I had to enable double/single threshold interrupt.
I had read that this register is 780mg/LSB.

Also datasheet says:
"The SHOCK_AXES register specifies the participation of each of the three axes in single shock/double shock detection."

How does it correlates to values in THRESH_SHOCK register.
Is it
THRESH_SHOCK = sqrt( (dataX * dataX) + (dataX * dataX) + (dataZ * dataZ) )

[hli]

Its b)
The resolution of the result is 49mg/LSB, whereas the offset registers have a resolution of 196mg/LSB (see register description).

For shock detection, look at page 26f of the data sheet. The shock detection works on the acceleration magnitude (which is the formula you have given). The SHOCK_AXES register allows you to supress some axes for the dection, and then your formula changes (if you use only one axis, then its THRESH_SHOCK=abs(dataX))