<p>Is there a way to read the current value of the 1.75's ambient light sensor? It'd be neat if that could be displayed by an activity.</p>
<p>--<br>
Nick Doiron<br>
Code for America </p>
<div class="gmail_quote">On Apr 9, 2012 9:16 AM, "Paul Fox" <<a href="mailto:pgf@laptop.org">pgf@laptop.org</a>> wrote:<br type="attribution"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
i just sent this to the folks working on the current doc sprint, and<br>
then realized it probably deserves a wider audience. operation of the<br>
brightness keys was enhanced a bit in 11.3.1, based on discussion on<br>
the devel list, but i don't recall that i ever sent out a summary mail.<br>
<br>
for convenience, i'm going to refer to the brightness keys as BrUp and<br>
BrDown here.<br>
<br>
on all laptops, in all sofware releases to date:<br>
<br>
- the unmodified BrUp and BrDown keys adjust the brightness in 15<br>
steps. when turning the backlight all the way off (i.e.,<br>
the lowest setting) the display will switch into the higher<br>
resolution monochrome mode.<br>
<br>
- using the Alt-BrUp and Alt-BrDown combinations will immediately<br>
change the backlight to its maximum and off values (including the<br>
change to monochrome when off).<br>
<br>
in release 11.3.1 and later, on all laptops:<br>
<br>
- the Ctrl-BrUp and Ctrl-BrDown combinations don't actually change<br>
the backlight level, but rather will toggle the screen between<br>
"normal" mode and the higher resolution monochrome mode. this<br>
monochrome mode will be sticky, so further normal use of the<br>
keys will adjust the brightness but won't restore color. this<br>
can be useful if you want the higher resolution, and don't<br>
currently need to have color displayed. unfortunately, there<br>
is currently no way to enter this "semi-permanent monochrome<br>
mode" via the Sugar user interface -- only Ctrl-BrDown will do it.<br>
<br>
and finally, on XO-1.75 only:<br>
<br>
- the backlight may automatically turn off when the laptop is in<br>
bright sunlight. when this happens, it is _not_ put into the<br>
hi-res monochrome mode. when the light level returns to<br>
"normal" -- i.e., indoor or shady light -- the backlight will<br>
be restored to its previous value.<br>
<br>
the ambient light sensor shares the opening in the plastic<br>
with the LED that looks like "(o)" near the lower left corner<br>
of the screen, so covering that location when outside, or<br>
shining a bright light on it when inside, may cause the<br>
backlight level to change.<br>
<br>
<br>
it's also worth noting that the F9 and F10 keys are, by default, the<br>
brightness keys, and are intercepted by system software before a<br>
running program can receive them. if the Fn key is pressed at the<br>
same time as F9 or F10, then the keys instead generate the true F9 and<br>
F10 codes, and are available to the current application (or perhaps<br>
the window manager). this is also true of the volume keys on F11 and<br>
F12 -- on any of our keyboards, holding Fn will force the top row of<br>
keys to generate F1 through F12.<br>
<br>
finally: all of the above functionality is available from the<br>
shell commandline:<br>
<br>
$ olpc-brightness -h<br>
usage: olpc-brightness [up|down|max|min|<0-15>|color|mono]<br>
<br>
<br>
paul<br>
=---------------------<br>
paul fox, <a href="mailto:pgf@laptop.org">pgf@laptop.org</a><br>
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</blockquote></div>