Build a digital compass

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Build a digital compass

Postby Scott McCrea » Aug 10, 2006 9:17 am

Tired of waiting for someone to make a digital compass for cave surveying? Then make your own. LINK
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Re: Build a digital compass

Postby Martin Sluka » Aug 15, 2006 6:27 am

Scott McCrea wrote:Tired of waiting for someone to make a digital compass for cave surveying? Then make your own. LINK


Is that compass able to measure as slopy shots as +-90 deg?
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Postby Lava » Aug 15, 2006 5:17 pm

That model of compass is horrible. If you tilt them even slightly or subject them to any kind of minor interference (at levels that any normal compass could handle), they go nuts on you.
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DIY Compass

Postby driggs » Aug 22, 2006 11:13 pm

The above-linked compass module and more details are available here:

http://www.acroname.com/robotics/parts/ ... MPASS.html

Unfortunately, as pointed out, it's not suitable for cave survey. The specs claim an accuracy of 3-4deg.

However, there's a new IC available from Honeywell, the HMC6352, that integrates all the junk on that board into a tiny SMD package, for even less money ($45/1), and with an accuracy of 2.5deg. It talks I2C and spits out ASCII bytes for dead-simple interfacing.

http://www.sparkfun.com/commerce/produc ... ts_id=7892

http://www.ssec.honeywell.com/magnetic/hmc6352.html

2.5deg accuracy still isn't good enough for stringent cave survey though. Maybe you could stick two of these tiny chips in a box and average their values for increased accuracy? :question:

Honeywell has lots of other magnetic sensors/compass modules, with up to 3 axis (compas and clino, XYZ) and 1deg accuracy... but they're priced in the if-you-have-to-ask-you-can't-afford-it category.
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