Brightness (While Plugged In)

[Yotto]

I like to leave the backlight on while my RockBoxed iPod is plugged in. I can do this easily with the "Backlight (While Plugged In)" option, turning it to "on"

However, while it's plugged in I don't need the backlight as bright as I keep it normally, and it just eats up (more) battery charge time. So, I was thinking how nice it would be to have a "Brightness (While Plugged In)" option as well, that I could turn down to the lower limits.

Is this feasible?

[tomers]

Is this feasible?

I it definitely feasible, but you'll have to convince others that it is really needed. TMHO, a new feature that is added to Rockbox must be relevant for a big enough audience, otherwise it does more harm than good (feature bloat).
I personally not sure it is a useful feature for many people, but that's just my opinion. Let's see what others think :-) Try contacting developers in IRC to discuss this.

[mcuelenaere]

Something like FS#10862?

[torne]

I was going to post and tell you that the brightness doesn't make that much difference, but I just tested it on my ipodvideo and it's a massive difference, for that model at least.

Player idle, backlight off (but LCD on): ~120mW
Player idle, backlight on minimum: ~165mW
Player idle, backlight on maximum: ~410mW

This actually means that if you charge while in Rockbox, having the backlight on full draws so much power that the battery won't really charge at all (because of the issue where we only draw 100mA from USB).

Having said that it also means that having the backlight up that bright means the battery drains at that rate, so hm.

[Yotto]

@tomers: I cannot say if it's feature bloat or not. I obviously would like it but if nobody else sees a use for it, I'm perfectly willing to do without. Same goes for if nobody feels like doing the work to add it. It's not like I'm offering, and my code likely would need fixing because I'm by no means a programmer.

@mcuelenaere: #10862 is for two backlight dimmers that work on their own timers, but function in every area of the firmware. I'm talking a backlight that has a different timer because it's in a different mode (powered instead of battery).

@torne: your quantitative numbers match with my qualitative analysis that led me to want this feature. The battery obviously takes longer to charge when I have the screen on than when it's off.

[saratoga]

I was going to post and tell you that the brightness doesn't make that much difference, but I just tested it on my ipodvideo and it's a massive difference, for that model at least.

Player idle, backlight off (but LCD on): ~120mW
Player idle, backlight on minimum: ~165mW
Player idle, backlight on maximum: ~410mW

Ha I could have told you that LEDs use a LOT of power.  Particularly white ones.

[tomers]

@tomers: I cannot say if it's feature bloat or not. I obviously would like it but if nobody else sees a use for it, I'm perfectly willing to do without. Same goes for if nobody feels like doing the work to add it. It's not like I'm offering, and my code likely would need fixing because I'm by no means a programmer.

If this feature fixes 'broken' charging, then it is more important than I thought originally. Isn't there any work done ATM to have the iPod draw 500mA from the USB bus? Otherwise, Dimming LCD is just a workaround, doesn't it?
This feature might also be useful for those on-the-go, who want to save their laptops battery, too.

[Llorean]

If you wanted to save the laptop's battery, why would you leave the backlight on at all? Wouldn't you instead just have it timeout like normal and only show on button presses?

This feature's really only useful if you're trying to use the player and charge at the same time and for some reason need the backlight dimmer while using it and connected to a charger than when not connected to a charger.

Generally speaking shouldn't the same indoor backlight levels be acceptable when charging and not? If you need to see the screen (for whatever reason) the same level of brightness is generally needed indoors whether or not a cable is connected to the player, right?

[torne]

If this feature fixes 'broken' charging, then it is more important than I thought originally. Isn't there any work done ATM to have the iPod draw 500mA from the USB bus? Otherwise, Dimming LCD is just a workaround, doesn't it?

It doesn't fix broken charging, even with the backlight off entirely the charging speed is very slow. I'm working on revamping usb charging, yes.

[Yotto]

This feature's really only useful if you're trying to use the player and charge at the same time and for some reason need the backlight dimmer while using it and connected to a charger than when not connected to a charger.

Correct. It is a very specific thing I want.

Generally speaking shouldn't the same indoor backlight levels be acceptable when charging and not? If you need to see the screen (for whatever reason) the same level of brightness is generally needed indoors whether or not a cable is connected to the player, right?

Also correct, to a point. I *prefer* a certain brightness level (I think it's 6) but I am *capable of seeing* a lower level (I can read 2, though I wouldn't choose to when navigating menus and the like).

This would allow me to, while at work, have my ipod plugged in and be listening to it, and when a song comes on and I don't know the band I can just glance over and see it. It is merely for convenience. And, in fact, I have little problem just having it on at my normal brightness and accepting that it takes a little longer to get a full battery.

Again, I'm not trying to convince anybody they should do this. I'm merely explaining my reasons for wanting it.

[JdGordon]

my recommendation is put brightness on the quickscreen, or setup a .cfg with just the brightness setting.

[Llorean]

Aren't the iPod 5G screens visible without the backlight? I know my 1st gen Nano's is quite visible without any backlight whatsoever as long as I use a suitable theme.

That, of course, would speed up charging even more.

[Yotto]

@JdGordon: Those solutions are a little more manual than I was hoping for. Knowing me, I'd forget to turn it off and listen for hours with it in my armband, shining the light out to the left draining the battery.

@Llorean: I'm not sure what version it happened in, but on my Video when the backlight turns off the lcd also turns off. I don't know how much battery it saves but I presume it's enough for someone to put it in, and is therefore significant.

[Llorean]

Isn't the LCD turning off optional on targets where the screen can be seen?

[torne]

There is a separate setting to control whether the LCD should be powered off on the ipods, yes.