| Have you considered integrating the signal? I'd suspect that on average,
| "up" would be the 'average' of the roll and pitch over a period of time.
| Interesting engineering problem.

The ADXL202 is a two axis device. It measures the gravitional acceleration
vector on mutually perpendicular axes defined by the top face of the IC.
Check the data sheets at Advanced Micro Devices' web site to see how this
works.

I routinely integrate the measurements on both axes by making 10 readings on
each. This does nothing to compensate for the skewing of the ADXL's axes
relative to the axes of the device that it is mounted on. I believe this to
be a geometry problem.

HTH

Vic

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