Lcd Backlight Brightness Hw Hack?


DaveC

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I was looking at newer updates of firmware and noticed that they cranked up the backlight brightness (not graphics brightness, that is different) to the point where it washes out blacks and colors. It is much too bright now. GPH seems to think cranking up the brightness to the point were things look overexposed looks good :blink: Some apps have brightness controls but that doesn't help blacks and can cause color clipping at the low end of the color values. This fact is keeping me at FW 1.0.1 as the brightness was correct only in that version. I suggested to some current FW hackers that a backlight brightness control be put into the FW. I didn't get much response there so maybe it is hard to figure out in software. I know that GPH knows how to do it in software so it is not impossible. The question is WILL it be done?

I don't want to waste the time to do it if someone is working on it though. Does anyone know if there are any software gurus working on this or will GPH maybe put in a backlight brightness control? This would be cool as it would let the user tweak the brightness to their liking (could also save power and the backlight on lower settings) . The PSP, DS lite, GBA-SP have backlight brightness controls.

So if no one is willing (or able) to do it in software I was thinking of doing it in hardware. What I would do is put a pot to adjust the voltage to the backlight to get different brightnesses. Would anyone be interested in this hack if I did it?
 

Radek

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DaveC posted on Mar 17 2006 at 06:14 AM said:
So if no one is willing (or able) to do it in software I was thinking of doing it in hardware. What I would do is put a pot to adjust the voltage to the backlight to get different brightnesses. Would anyone be interested in this hack if I did it?

Good idea but how do you plan make connections (and where)?

The signal tape to the lcd is very delicate, soldering in mainboard is big no here as the place around socket is populated by SMD parts and where you would put a pot in the GP2x's case (need of drilling)?

You might have a perfectly workable idea but it's looking quite troublesome for me. But would be great if done.

Another good idea would be make sound volume regulator - should be far easier to make and equally usefull.
 
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garteth

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I noticed this too, after upgrading from firmware 1.0 to 1.2.1 the screen became blinding and it starts to make my eyes ache when im playing in the dark, when the brightness was lower it was much easier on the eyes. I hope there is some kind of software fix for this.
 

DaveC

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Radek posted on Mar 17 2006 at 08:48 AM said:
DaveC posted on Mar 17 2006 at 06:14 AM said:
So if no one is willing (or able) to do it in software I was thinking of doing it in hardware.  What I would do is put a pot to adjust the voltage to the backlight to get different brightnesses.  Would anyone be interested in this hack if I did it?

Good idea but how do you plan make connections (and where)?

The signal tape to the lcd is very delicate, soldering in mainboard is big no here as the place around socket is populated by SMD parts and where you would put a pot in the GP2x's case (need of drilling)?

You might have a perfectly workable idea but it's looking quite troublesome for me. But would be great if done.

Another good idea would be make sound volume regulator - should be far easier to make and equally usefull.

It wouldn't be that hard if you have the soldering skills. I have done many mods on small circuits like this. It would involve cutting a trace and finding appropriate solder points one being the pin on the ribbon socket.

The pot would be small and drilling not a big deal, certainly much less surgery than the D-pad replacement that you are doing.

Software would be best but who knows if that will be done. It doesn't seem like any coder has had any interest in a backlight brightness setting. If it was done in software you could use the same screen that I made for the timing setting. I guess we could wait to see if GPH gives us a user selectable setting in later FW but knowing them I wouldn't hold my breath.

A sound volume regulator would be good except how would you bypass the software sound regulation? That would be extremely difficult I would think.
 
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aapje89

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garteth posted on Mar 17 2006 at 10:45 AM said:
I noticed this too, after upgrading from firmware 1.0 to 1.2.1 the screen became blinding and it starts to make my eyes ache when im playing in the dark, when the brightness was lower it was much easier on the eyes. I hope there is some kind of software fix for this.
But who playes it the dark? :huh:

And yes, I think a software mod is better than a hardware mod.
Sound volume regulator sounds nice aswell :), but do you mean a hardware or software mod?
 
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racoon

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*raises hand for software mod*
if it was darker earlier, it can be darker in the future as well ;D
regultor would be nice :)
 

DijiTao

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I think we all want a software mod and it *should* be possible as it's been demostrated by the differences in the firmwares that this is controled by software. The question is: Is anyone working on this?
 

garteth

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aapje89 posted on Mar 17 2006 at 04:34 PM said:
garteth posted on Mar 17 2006 at 10:45 AM said:
I noticed this too, after upgrading from firmware 1.0 to 1.2.1 the screen became blinding and it starts to make my eyes ache when im playing in the dark, when the brightness was lower it was much easier on the eyes. I hope there is some kind of software fix for this.
But who playes it the dark? :huh:

And yes, I think a software mod is better than a hardware mod.
Sound volume regulator sounds nice aswell :), but do you mean a hardware or software mod?

Well I use it to read ebooks at night and sometimes play some games in bed (not the sexual kind ;) )
 
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cbox

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Just go back to an older firmware, I'm running 1.1 and it's fine, don't have any plans to update any time soon since everything works fine to me.
 

Radek

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DaveC posted on Mar 17 2006 at 05:22 PM said:
Radek posted on Mar 17 2006 at 08:48 AM said:
DaveC posted on Mar 17 2006 at 06:14 AM said:
So if no one is willing (or able) to do it in software I was thinking of doing it in hardware. What I would do is put a pot to adjust the voltage to the backlight to get different brightnesses. Would anyone be interested in this hack if I did it?

Good idea but how do you plan make connections (and where)?

The signal tape to the lcd is very delicate, soldering in mainboard is big no here as the place around socket is populated by SMD parts and where you would put a pot in the GP2x's case (need of drilling)?

You might have a perfectly workable idea but it's looking quite troublesome for me. But would be great if done.

Another good idea would be make sound volume regulator - should be far easier to make and equally usefull.

It wouldn't be that hard if you have the soldering skills. I have done many mods on small circuits like this. It would involve cutting a trace and finding appropriate solder points one being the pin on the ribbon socket.

Yes - I didn't say that it impossible but still... it must be done carefully. I'm certain you are able to do something like that. I hope what I said wasn't implying that you don't. If so then sorry.

DaveC posted on Mar 17 2006 at 05:22 PM said:
The pot would be small and drilling not a big deal, certainly much less surgery than the D-pad replacement that you are doing.

Yes and no.

Mechanically for sure because... it's obvious.

Electrically much less because I didn't solder on the GP2x's mainboard anything (and don't plan too)

DaveC posted on Mar 17 2006 at 05:22 PM said:
Software would be best but who knows if that will be done. It doesn't seem like any coder has had any interest in a backlight brightness setting. If it was done in software you could use the same screen that I made for the timing setting. I guess we could wait to see if GPH gives us a user selectable setting in later FW but knowing them I wouldn't hold my breath.

A sound volume regulator would be good except how would you bypass the software sound regulation? That would be extremely difficult I would think.

A kernel linux module what would be from time to time overriding the aplication control. There are already interrupts working all the time so that shouldn't be big deal.

Anyway even without such overriding volume regulator would be usefull.
 
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DaveC

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cbox posted on Mar 17 2006 at 06:56 PM said:
Just go back to an older firmware, I'm running 1.1 and it's fine, don't have any plans to update any time soon since everything works fine to me.


Yeah but the problem is that you can't use 2 or 4 gb cards with such an old FW. I want to use a 4 GB card. Swapping small capacity cards all of the time sucks.
 
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lucoxade

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Have you tried theoddbots gamma correction tool that fixes the gamma on the chip to make everything look nice again?

But I know what you mean, it would be cool to have a dial to adjust the actual brightness, like with the afterburner on the GBA
 

airwolf

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lucoxade posted on Mar 17 2006 at 03:15 PM said:
Have you tried theoddbots gamma correction tool that fixes the gamma on the chip to make everything look nice again?

But I know what you mean, it would be cool to have a dial to adjust the actual brightness, like with the afterburner on the GBA

Do you have a link? Never heard of that proggy...
 
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EvilDragon

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A hardware fix might be hard. I can tell you which resistor it is - but if you change it, your screen will start flickering again.
The First Editions (the first ones) has a different resistor. Gamma and brightness was fine, but they began to flicker.
 

DaveC

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lucoxade posted on Mar 17 2006 at 09:15 PM said:
Have you tried theoddbots gamma correction tool that fixes the gamma on the chip to make everything look nice again?

But I know what you mean, it would be cool to have a dial to adjust the actual brightness, like with the afterburner on the GBA


Yeah but his tool only adjusts the brightness of the graphics and has absolutely no effect on the backlight brightness and black level like the different FW versions do. His tool is like going into DrMD and adjusting the brightness, no effect on the backlight.


EvilDragon posted on Mar 17 2006 at 09:25 PM said:
A hardware fix might be hard. I can tell you which resistor it is - but if you change it, your screen will start flickering again.
The First Editions (the first ones) has a different resistor. Gamma and brightness was fine, but they began to flicker.


What you are talking about is the LCD itself. I am not refering to anything to do with the graphics displayed on the screen. What I am talking about is the LED backlight. That fix would be a simple pot regulating the voltage to the LEDs and would have no effect on the timing or voltage bias to any actual pixels.
 
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DaveC

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cbox posted on Mar 18 2006 at 12:52 AM said:
2 and 4 gig cards work fine with version 1.1

Wasn't the brightness cranked up in that release? I think the latest FW release that has correct (darker) gamma is 1.0.1.
 
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