If you are starting a new design, I would use the new ones from MEMSIC.
Much cheaper than the ADXL accelerometers, and supposedly more robust
(although I have never had a problem with ADXL202s).  If it didn't mean a
redesign of the board and major mods to the software, I would be using these
now.

Martin



-----Original Message-----
From: pic microcontroller discussion list
[mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Brent Brown
Sent: 22 August 2001 22:07
To: PICLIST@MITVMA.MIT.EDU
Subject: Re: [EE]: 3 axis magnetometer design ideas sought.


> > The magnetic field vector is (at least for low altitude flights) to
> > be considered constant in terms of both magnitude and direction.
> > Measuring and recording the time history of the magnetic field  from
> > a 3-axix magnetometer will allow You to figure out the rocket
> > pitches and rolls with respect to the (fixed) earth magnetic field
> > vector. Converting to a coordinate system of Your own liking may be
> > done either by measureing the earth magnetic field vector in that
> > particular coordinate system, or simply by offsetting the initial
> > conditions.

Could you acheive the same thing by using a couple of ADXL
accelerometers? (Each chip can have 2 axis). Haven't used one
myself yet but they look really cool and I'm just dying for an
application to come along.

Brent Brown
Electronic Design Solutions
16 English Street
Hamilton, New Zealand
Ph/fax: +64 7 849 0069
Mobile/text: 025 334 069
eMail:  brent.brown@clear.net.nz

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