digital compass modules

Schmidt András asch at
Wed Jan 23 15:11:35 CET 2008

François TOURDE wrote:
> Le 13901ième jour après Epoch,
> Schmidt András écrivait:
>> Tilman Baumann wrote:
>>> Bluetooth would be nice. You would need no hardware hacks on the
>>> phone itself.
>>> Should be pretty easy to hack a bluetooth->serial converter (like
>>> BlueSMiRF from sparkfun) to the sensor. Maybe with a little
>>> microcontroller glue in between.
>>> Bluetooth is very simple to code and simple to handle.
>> I was thinking about two possible applications:
>>   1. The map of a GPS map viewer application turns when you turn the
>>      machine so it is always aligned with the environment (this feature
>>      is included on some GPS tools.)
> Maybe the 3D accels can do that. And the GPS can be used as a bearing
> indicator, when you move. No magnetic device needed in this case.
Right! That was an other possible solution I was thinking about. Though 
I think that algorithm should be very carefully implemented (a very 
sensitive regulator filter) not to accumulate the measurment error of 
the accelerometer, and corrigate with the GPS signal when possible. I am 
not even sure it is possible. Precision would get worse when you are 
moving slow and shake the device (the case on foot). The regulator code 
would also consume much energy. Direct measurment of direction seems to 
be much better for me.

These are only speculations with little information and no experience 
with such devices (accelerometer and magnetic sensor in fact).

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