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Re: [sensors] Address questions around exposing high-level, low-level, and uncalibrated sensors

From: Tobie Langel via GitHub <sysbot+gh@w3.org>
Date: Wed, 17 Jun 2015 14:42:21 +0000
To: public-device-apis@w3.org
Message-ID: <issue_comment.created-112827506-1434552141-sysbot+gh@w3.org>
Sorry, I meant "uncompensated" and not "uncalibrated" (please bear 
with me).

So I was looking at the BMP series of barometer sensors (that are 
[supported in Johnny-Five][1] and which [apparently also power the 
iPhone 6][2]), and it appears that these sensors all have an 
integrated temperature sensor that is used to compensate the values of
 the pressure sensor and not (only?) to help calculate the altitude as
 you seem to indicate in 
https://github.com/w3c/sensors/issues/51#issuecomment-112595749.

So I have a bunch of follow up questions:

* For this particular case, where two sensors on a single sensor are 
used to provide compensated data to improve the overall quality of the
 readings, what should be exposed to the Web platform?
    1. the compensated pressure reading only?
    2. the compensated pressure reading and the temperature reading?
    3. the compensated pressure reading, the uncompensated pressure 
reading and the temperature reading?
    4. the compensated pressure reading and the uncompensated pressure
 reading?
    5. something different?
    6. leave that up to the implementor?
    7. leave that up to the barometer spec.

* From the barometer data, it seems easy to get elevation data using a
 bit of math, the temperature(?) and a few constants (mean pressure at
 sea level, something else?). Should a separate `new 
sensors.Altimeter()` be also exposed in that case?

Note, I'm taking `Barometer` as an example here, but you get the idea.

[1]: https://github.com/rwaldron/johnny-five/blob/master/lib/imu.js
[2]: http://www.techinsights.com/teardown.com/apple-iphone-6/

-- 
GitHub Notif of comment by tobie
See https://github.com/w3c/sensors/issues/51#issuecomment-112827506
Received on Wednesday, 17 June 2015 14:42:26 UTC

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