Using an H48C accelerometer

pjr

I'm starting a prop based project, that among other devices, will interface to a H48C 3-axis accelerometer.
Going through the spin object that interfaces to the Parallax module (#28026), I've noticed that besides retrieving the G's for each axle, you can also get angles between them (Theta's)...
However, I couldn't understand what they represent, and what could they be used for. Any ideas ?

Thanks

Beau Schwabe

pjr,

Welcome aboard!

The theta returned is a 13-Bit angle that is derived from the "RAW" X,Y and Z values.

A 13-Bit angle simply means that instead of 0 to 359, the values range from 0 to 8191. To convert the 13-Bit angle into Deg ...

Deg = ({13-Bit Angle} * 45 ) / 1024

Angles are derived by combining only two of the X,Y, and Z coordinate values into a Cartesian to polar conversion routine that results in the equivalent deg.

Theta A - uses the XY Cartesian coordinate plane to derive a 13-bit angle
Theta B - uses the XZ Cartesian coordinate plane to derive a 13-bit angle
Theta C - uses the YZ Cartesian coordinate plane to derive a 13-bit angle

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Beau Schwabe

IC Layout Engineer
Parallax, Inc.

Post Edited (Beau Schwabe (Parallax)) : 5/8/2009 4:24:23 PM GMT

pjr

Beau,

But what do the angles mean ?
For instance, Theta A: does it mean the current angle just described in the XY plane by the H48C chip ?


Paulo