rapid backlight switching - is that bad?


_wb_

Microbe
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I'm currently working on a nice flashlight tool for the Pandora. I want the tool to adjust the backlight brightness depending on the brightness of the color to be shown: I want the user to be able to smoothly dim a light from #FFFFFF at brightness 54 all the way down to #000000 at brightness 0.


The tool will also have stroboscope and color cycling modes: would it be a good idea to actually switch off the backlight (set its brightness to 0) when the stroboscope goes black (currently I just set the color to black, but that is not quite the same thing, esp at high brightness)? Or would rapidly switching the backlight on and off be a bad idea - will it break the backlight at some point? And how much time does the backlight need to power up or down (i.e., how many Hz can a stroboscope implemented in this way do) ?
 
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I can't find the info confirming if its a LED or not.


but if its an LED backlight there shouldn't be a problem as dimming the screen is actually done with PWM: turning the LEDs on and off extremely quickly.


if the backlight is NOT LED then it could damage it.


... do they still make/use LCDs with fluorescent tubes devices rather than LEDs for portable ?
 
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mcfab

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Hi _wb_


Newbie here.


Good idea! As every handheld in the world, OP shoud have its flashlight application!


I like the stroboscope function. Do you plan to allow frequency control ?


Some time ago I've managed to code my own flashlight for my GP2X-WIZ but never finished it.


Here are the stock functions that were planned:


- Fullscreen/window mode.


- Choice of "primary" colors (white, red, green, blue, etc)


- Brightness adjustment through screen backlight or color emulation .


- Autosave current light state, so the user can instantly retrieve it on next app launch.


- 3 programmable timers : auto power-off, fade in and fade out


- 2 buttons to control the light:


. A tactical button (pressed=light-on , released=light-off)


. A switch button (one press=light-on, 2nd press=light-off)


This is just in case your are looking for some ideas.


Please forgive me if you don't ;)


Thanks for sharing.
 

_wb_

Microbe
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Well, now the Pandora has its very own flashlight app :)


I just released version 0.1 of my flashlight application (just before I read your post):


http://boards.openpandora.org/index.php?/topic/9096-pandora-flashlight/


Looks like I already implemented most of your features :)

I like the stroboscope function. Do you plan to allow frequency control ?

Yes, you can make it go faster or slower, no way to input exact Hz or something like that though.

- Fullscreen/window mode.

No window mode for me, since I'm using notaz' SDL. Why would you want windowed mode?

- Choice of "primary" colors (white, red, green, blue, etc)

Check.

- Brightness adjustment through screen backlight or color emulation .

Check.

- Autosave current light state, so the user can instantly retrieve it on next app launch.

Nope, but I do have 10 save slots, and the color from the first slot will be auto-loaded on launch. So you actually have to "manually" save to slot 1 instead of having autosave.

- 3 programmable timers : auto power-off, fade in and fade out

Nope, don't have that. Nice idea! Might implement that at some point.

- 2 buttons to control the light:


. A tactical button (pressed=light-on , released=light-off)


. A switch button (one press=light-on, 2nd press=light-off)

Yep, have those (left and right shoulder buttons, respectively).
 
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