Re: Proposed addition to 'IIO interface' for color light sensingdevices

From: Jonathan Cameron
Date: Wed Apr 04 2012 - 04:39:34 EST


Not sure who else would be interested in this discussion so if anyone can cc
any interested parties that would be great! (
I would like to propose the following addition to the 'IIO device
interface' for color light sensing devices to accommodate CCT (AKA color
temperature) and access to the raw RGB channel data for user analysis.

IIO channel type name: CCT

The CCT ABI should be documented similar to as follows:
In sys-bus-iio-light:
What: /sys/bus/iio/devices/device[n]/cct[_input|_raw]
KernelVersion: 3.3.0
Contact: linux-iio@xxxxxxxxxxxxxxx
Description:
This should return the correlated color temperature from
the RGBC color sensor
expressed as SI unit (degree kelvin).
If it comes back in SI units, it should also
include_input else it
should include _raw to signify it is not in SI units.
Works for me though the formatting of the above is somewhat different from
our current docs...

IIO modifiers:
IIO_MOD_LIGHT_RED
IIO_MOD_LIGHT_GREEN
IIO_MOD_LIGHT_BLUE
So these modifiers apply to intensity channels? Colour temp is built from
multiple raw sensors I believe (like illuminance is often done?)
Hence it's another 'virtual' channel we compute?

The 'clear' and IR channels are already covered by the use of IIO_LIGHT
and IIO ILLUMINANCE (and respective modifiers).
The RGB modifiers will help to express the relative frequencies to their
respective channel, and appear to fit well with the overall convention.

And last but not least, the textual modifier names "red", "green", and
"blue" be accommodated within 'industrialio-core'.
Fine with me.


Channel specific interrupt event / sources are not presented at this
time.

Any thoughts or comments are welcomed.

Jon Brenner

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