[Request] Status-menu plugin to enable/disable the hardware keyboard's backlight - maemo.org

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kent_autistic	2012-04-16 , 11:10
Posts: 304 \| Thanked: 235 times \| Joined on May 2010 @ Manila	#1

There are times when I want to use the hwkb but often worried that it would use up battery power due to the backlight leds being lighted up for some time. So a status menu plugin to enable/disable it would be really helpful.

I want to pop out the hwkb and not have the backlight lit up, and when I need it to light up, I can easily enable it through the status-menu.

I hope it is possible. TIA!

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	joerg_rw	2012-04-16 , 12:14
	Posts: 2,222 \| Thanked: 12,651 times \| Joined on Mar 2010 @ SOL 3	#2

the kbd backlight is controlled via mce process and lp5523 kernel driver in /sys/class/leds/lp5523:kb?/* and engine3.
Possible hooks are:
/etc/mce/mce.ini ([KeyPad] BacklightTimeout=30) problem: mce needs a restart to read in new values from mce.ini
/sys/class/leds/lp5523:kb?/led_current
/sys/class/leds/lp5523:kb?/brightness
/sys/class/i2c-adapter/i2c-2/2-0032/engine3_mode

see http://wiki.maemo.org/N900_Hardware_LED and http://wiki.maemo.org/LED_patterns#Low_Level for details.

Code:

for L in /sys/class/leds/lp5523:kb?; do echo 0 >$L/led_current; done

is accomplishing a shutdown of backlight. Alas mce will restore the default value 50 to all led_current nodes when kbd backlight gets re-enabled. This also might happen on random moments, I haven't done extensive tests.
Beware! Values >50 for led_current may instantly kill your LEDs!

Anyway I hope it helps you with some suggestions where to start.

/jOERG

[edit] ps.: please notice your kbd backlight will get turned off when ambient light is bright enough

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Last edited by joerg_rw; 2012-04-16 at 13:01.

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kent_autistic	2012-04-16 , 12:16
Posts: 304 \| Thanked: 235 times \| Joined on May 2010 @ Manila	#3

thanks doc!

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	B-RUNO	2012-04-16 , 13:14
	Posts: 124 \| Thanked: 125 times \| Joined on Sep 2010	#4

Hello to all I just have a question it would be possible just leave some of the keyboad lights on, for example; when we are using an emulator and we have the keyboard mapped just leave the mapped keys with lights on! do you guys think this possible??

Just an ideia.
Bruno

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	Estel	2012-04-16 , 13:43
	Posts: 5,028 \| Thanked: 8,613 times \| Joined on Mar 2011	#5

MAG did a proof-of-concept program that turned certain diodes beneath keyboard on demand (there are 6 diodes total out there), so it's probably perfecdtly achievable.

Yet, You guys are overrating effect on battery life, generated by kb diodes - they're not like backlight of screen, so don't expect noticeable powersaving, even by disabling them totally.

OZr I just don't feel it using 3000 mAh battery, which seems to be much more effective way of extending runtime

/Estel

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	B-RUNO	2012-04-16 , 18:51
	Posts: 124 \| Thanked: 125 times \| Joined on Sep 2010	#6

Originally Posted by Estel

MAG did a proof-of-concept program that turned certain diodes beneath keyboard on demand (there are 6 diodes total out there), so it's probably perfecdtly achievable.

Yet, You guys are overrating effect on battery life, generated by kb diodes - they're not like backlight of screen, so don't expect noticeable powersaving, even by disabling them totally.

OZr I just don't feel it using 3000 mAh battery, which seems to be much more effective way of extending runtime

/Estel

Thanks Estel, I'm not bothered with the battery consumption, I'm just interested on this concept because some times it is hard to remember which key I assigned on the emulatos, on that way would look like a proper console remote!!!

Bruno

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kent_autistic	2012-04-17 , 01:02
Posts: 304 \| Thanked: 235 times \| Joined on May 2010 @ Manila	#7

Originally Posted by joerg_rw

[edit] ps.: please notice your kbd backlight will get turned off when ambient light is bright enough

thing is, i have ALS sensor disabled

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	joerg_rw	2012-04-17 , 18:22
	Posts: 2,222 \| Thanked: 12,651 times \| Joined on Mar 2010 @ SOL 3	#8

with those 6 diodes you hardly can illuminate particular keys while keeping others dark.

For Mohammad's POC (actually iirc I posted him how to do it ;-D), you simply add a

Code:

sleep 1

to inside the for-loop of my code snippet above ;-)

regarding power consumption: 6 * 5mA * ~2V = ~60mW
screen backlight is using up to 15 times that, iirc and my math still works

/j