are studying to use ADXL345 and we are doing some trials. We measure one single
axis accelerometer, now board is placed horizontally so we are using Z axis.
As noise and offset are accumulated during integration, is there any “better
axis” to calculate this integration? (let say, using X axis measurement instead
of Z axis because may be this is less offset, lest drift or may be less noise
…) Lookin on page 4 of the datasheet it seems Z axis is “worse” specs..
You are correct. X/Y axis performance is better than Z axis.
You can make the board vertically to use X/Y axis.
Regarding integration, you have to calibrate the offset of the axis that you
are interested in or else the offset will dominate the total error.
Attached is a brief introduction about how to calibrate the offset of ADXL345.
Of course, if you use a high pass filter, the offset issue can be ignored.
Whether the HPF can be used or not depends on your interested frequency range.