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Old 10-06-2012, 07:14 PM   #4
geekmaster
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Join Date: Nov 2011
Device: Kindles,Nooks,etc.
First, we will read current brightness values set from the desktop framework.

Asleep, screensaver image or ad showing:
[root@kindle /]# cat /sys/devices/system/fl_tps6116x/fl_tps6116x0/fl_intensity
FrontLight(Intensity) = 0


Awake, slider at maximum brightness:
[root@kindle /]# cat /sys/devices/system/fl_tps6116x/fl_tps6116x0/fl_intensity
FrontLight(Intensity) = 254


Slider adjusted to minimum brightness (almost off):
[root@kindle /]# cat /sys/devices/system/fl_tps6116x/fl_tps6116x0/fl_intensity
FrontLight(Intensity) = 1


Slider adjusted to medium brightness:
[root@kindle /]# cat /sys/devices/system/fl_tps6116x/fl_tps6116x0/fl_intensity
FrontLight(Intensity) = 36


Now we will see if we can CHANGE the screen brightness from the command line:


Lets try to SET maximum brightness:
[root@kindle /]# echo -n 254 > /sys/devices/system/fl_tps6116x/fl_tps6116x0/fl_intensity
Yes, it works!

Now let's try to turn it COMPLETELY off:
[root@kindle /]# echo -n 0 > /sys/devices/system/fl_tps6116x/fl_tps6116x0/fl_intensity
Yes, it is completely off even while awake!

Now, lets put the Paperwhite asleep by tapping the power button. The light is off. Now set maximum brightness:
[root@kindle /]# echo -n 254 > /sys/devices/system/fl_tps6116x/fl_tps6116x0/fl_intensity
Yes, it is showing the screensaver image at maximum brightness.

Now let's turn the screensaver light off again to save battery:
[root@kindle /]# echo -n 0 > /sys/devices/system/fl_tps6116x/fl_tps6116x0/fl_intensity
It is off again.

Now, I think that is useful!

EDIT: Now that we know how to change screen brightness from the command line, it is time to write a script to blink out Morse Code messages...

Last edited by geekmaster; 10-07-2012 at 02:25 AM.
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