Standby Mode On Pandora ?

[aznJun]

i was just wondering...
can the Pandora go into a shut down mode...
like the PSP?
or is it more like laptops... where it still consumes battery if u put it on standby?

-aznJun

 

[Squidge]

i was just wondering...
can the Pandora go into a shut down mode...
like the PSP?
or is it more like laptops... where it still consumes battery if u put it on standby?

-aznJun

If you put it in standby, it will still consume battery power (though much less).

If you put it hibernate or off state, it will draw almost zero power. I say "almost zero" as it will probably still draw some power, but it will not be noticable (It would probably be 3 months or so before it needed a recharge, which, after that amount of time, you should recharge the battery anyway, even if it's not in the device).

So yes, it can go into a shut down mode like PSP (PSP does the same as above).

 

[aznJun]

QUOTE

If you put it in standby, it will still consume battery power (though much less).

If you put it hibernate or off state, it will draw almost zero power. I say "almost zero" as it will probably still draw some power, but it will not be noticable (It would probably be 3 months or so before it needed a recharge, which, after that amount of time, you should recharge the battery anyway, even if it's not in the device).

So yes, it can go into a shut down mode like PSP (PSP does the same as above).



doesnt hibernating damage your battery?
like laptops? because i heard that if u put ur laptop to hibernation
it causes problems with the batteries...

-aznJun

 

[Null]

doesnt hibernating damage your battery?
like laptops? because i heard that if u put ur laptop to hibernation
it causes problems with the batteries...

No.

 

[Squidge]

doesnt hibernating damage your battery?
like laptops? because i heard that if u put ur laptop to hibernation
it causes problems with the batteries...

Then I would say that you heard wrong. Hibernation is almost the same as switching the device off with the only difference being that the contents of memory are temporarily stored on disk. It'll use the same amount of power as switching the unit off.

The problems with laptops is the operating system and drivers. For example, it's known that a Windows Vista laptop can wake up from hibernation, do some "house keeping", and then go back to sleep. Completely pointless and battery wasting, but that's Microsoft for you. End result is that you battery can drain whilst you sleep.

Pandora will only wake up when you tell it to

 

[Chip]

It seems that some people are confused by the different power saving modes that exist for portable computers. Let me see if I can clear things up.

There are basically three modes between "on" and "off" that a computer can be in:

Display off - It's just what it sounds like. The LCD consumes a portion of a system's total power draw. You can save that power by shutting it down when you're not using it. This should not be confused with a screen saver, which just blanks the display. The actual power savings depends on the system, but it is significant. The rest of the system continues along as if nothing has changed, consuming power at its regular rate.

Suspend to RAM - Also sometimes called "sleep mode", suspend to RAM basically freezes all running processes and shuts down everything except the system memory. The only power consumed is what is required to refresh that memory. The Pandora uses Low Power (LPDDR) memory, which has several ultra low-power modes. These modes do things like refreshing the memory banks less frequently and only refreshing banks which are actually in use (more info here). Waking from suspend to RAM mode is nearly instantaneous.

Suspend to Disk - Also called "hibernate". When the computer goes into this mode, it copies the contents of the system memory to either a special file or partition on the main disk (in this case, an SD card) and shuts down completely. When in this mode, there is absolutely nothing (except the RTC, but lets not split hairs) drawing power from the system battery. Hibernating your computer is actually more power efficient than shutting it down, as the system wastes less time (and power) going into and coming back out of hibernate mode than it does shutting down and starting up. There is still some time delay though - basically however long it takes to copy the system memory to and from non-volatile storage. In the case of the Pandora, it would take about 6 sec @ 20MB/s to copy a 128MB RAM image from an SD card to memory.


All three modes will be available on the Pandora, and should be fully configurable through software. What that means is if you only want to shut the display off when you close the lid so MPlayer will keep playing your MP3s, that is an option. If you prefer to have it go into suspend to RAM mode when you close the lid, that is an option too. If you want the power switch to make the system hibernate instead of actually shutting down, that should also be an option. Under normal usage conditions, you will hardly ever have to actually shut down the device. It makes much more sense to use the other low-power modes between sessions. This makes concerns over "boot up time" completely irrelevant.

 

[Karel Jansens]

Would it be possible to apply those power settings at the application level, meaning that e.g. closing the lid in mplayer will only switch off the LCD, but closing it in GPE Contacts will suspend to RAM?

And can this be done by the user, or does the programmer need to provide that functionality?

 

[Squidge]

There will probably be an API for power management sometime in the future, but each program would have to state what it wanted to happen (Ie, it would set a maximum power saving level, such as "LCD off only" rather than STR).

 

[Creature XL]

That sound to me like another session, and it shouldn't take THAT long to recover from hibernate. Probably less than a full boot-up

Certainly less than a full boot up. It should only take as long as it takes to transfer the 128MB memory image from the SD card to the RAM. At 20MB/s that's about 6 sec.


Sorry in advance for diggin ghtis thread up again.

Wouldn't it be possible to crunch teh RMa data while doing the hibernate?
Just as an example you can have a lok at UPX's Website.

You find there: "very fast decompression: ~10 MB/sec on an ancient Pentium 133, ~200 MB/sec on an Athlon XP 2000+."

If we assume that the Pandora would reach ~50Mb/sec it would be ~2 sec.
You have to consider two facts:
1.) it is no problem when the hibernation takes 5 seconds longer. When I will close my Pandora to hibernate it, I don't care about some seconds. Its like "Clsoe and Forget"

2.) It doesn't have to be fancy stuff like UPX, a simple RLE would do a great job if, lets say, 64Mb of the 128Mb are blank (or not used to be precise. LiNUX will not fill unused pages with zeros). You can just save unused pages with four bytes

 

[mannowhere]

I, too, am dredging this thread up from the dead as it comes closest to answering my question (I did what I was supposed to do: use the search function to find an answer before posing a question), but doesn't really do so.

I am looking at this device to be what the later Sharp Zaurus clamshell models could have been had Sharp just listened to their users and included Wi-Fi (among other grumbles). I had an SL-5500 and I really wanted one of the convertible clamshell models, but couldn't justify the cost. Now along comes Pandora (sans convertible option, but I can live with that if I must since it appears to hit all the other right notes) at a surprisingly reasonable cost and I am seriously lusting for one.

However, since this device seems to be designed to function like a PC more than a PDA, I have one serious concern. I could set alarms on my Zaurus and have the device turn itself on and play a sound. I presume it was done by setting an alarm on the RTC and having said RTC power up the device when it was time to do so. Will the Pandora be able to do this from hibernate mode, or would it only work in suspend mode (presumably because the RTC couldn't wake up the device)? I know I may have to wait for the software to be written to do this (or learn to do it myself, perhaps using the old Zaurus stuff as a base). If the RTC clock can't wake the device from an "off" state, then that is a deal-breaker for me.

Can anyone tell me if the RTC on the Pandora can wake the device from an "off" or "hibernate" state?

 

[bigtruck]

While I'm just speculating, I rather doubt it can be woken up from an "off" state, which includes suspend to disk (hibernate), since that is essentially "off", except it just boots faster and saves your session. However, I think it's generally possible to wake up linux machines from a suspend to ram at a preset time. Also, the latest information we have is that the Pandora should theoretically last for about two months in suspend to ram with a full battery. So unless you want the Pandora to wake a few months in the future, you should be fine.

 

[mannowhere]

The Real Time Clock (RTC) should always be "on" and running as long as there is juice in the battery, even when the device is in an "off"/"hibernate" state - that's the whole purpose of an RTC (basically like the "CMOS battery" in a typical PC powers an internal RTC). What isn't clear to me is whether this particular RTC has alarms (they typically do) that can "wake up" the device (not so sure on this point). Presumably, there'd have to be a daemon running that looked for the next alarm in your schedule and set the RTC's alarm accordingly whenever the device is turned on.

 

[Squidge]

The Pandora has an RTC which can interrupt OMAP and wake it up. However, if the OMAP is turned off (Hibernation) then it's likely that the RTC interrupt to the OMAP will be ignored, as there will be no power for it to check for interrupts. However, there could be other sleep modes which allow the RTC Alaram function to work (and as has been said already, the device could stay in these modes for several months before hibernating).

 

[MilanC]

Seems STR is all we'll ever need . but then, STD won't hurt.

Things I'd like to know though [ off-topic but still about power saving ], are whether it will be possible to use an external light source with the screen (i.e. sunlight) and shut down the backlight, and how long it should be possible to use the Pandora underclocked very far down (perhaps under 100MHz) and with backlight set to minimum, idle DSP, no 3D, no sound, no wireless... (pandebook/notepa(n)d)

 

[God Ginrai]

I, too, am dredging this thread up from the dead as it comes closest to answering my question (I did what I was supposed to do: use the search function to find an answer before posing a question), but doesn't really do so.

4 days is hardly gravedigging. And I commend you for using the search function. ^_^

-God Ginrai

 

[mannowhere]

The Pandora has an RTC which can interrupt OMAP and wake it up. However, if the OMAP is turned off (Hibernation) then it's likely that the RTC interrupt to the OMAP will be ignored, as there will be no power for it to check for interrupts. However, there could be other sleep modes which allow the RTC Alarm function to work (and as has been said already, the device could stay in these modes for several months before hibernating).

Any way of determining that for certain before I commit to this device? I would imagine that such a feature would also be important to many other users for whom Pandora's potential as a PDA ranks high among their priorities. Unfortunately, my circumstances have changed drastically since I purchased my now-defunct Zaurus (oh so many years ago) and I cannot so easily afford even the lower cost of the Pandora without being certain it'll do what I need. If the hardware engineers and/or system devs behind this great project could confirm the existence of a very low-power mode that'll still allow the RTC to wake the device up then I'll buy two of these and be happy as the proverbial pig in shit (learned the hard way from the loss of my Z to have a backup device, although the second Pandora will most likely come from a later run).

MilanC, I've no idea what you mean by the acronyms in your first line, so I can't tell if you're being sarcastic or not. However, from what I've read when researching before posting, turning off the backlight will definitely be possible (although I'm not knowledgeable in LCD screen types and so cannot comment on how well an external light source will work). As far as your question regarding the runtime in a significantly reduced power mode, specific answers will be hard to come by before the device actually gets manufactured. Nonetheless, as Squidge pointed out, it has already been established that the extreme low-power modes can be made to last for a very long time indeed -- exactly how much will be determined by which of the apparently myriad options are employed.

Ginrai, thanks for the compliment. I was referring to the fact that the thread hadn't been active for two months prior to the post preceding my initial one.

 

[Tom`]

STR is suspend-to-RAM, which is what most PDAs do. It should be able to stay in this state for quite a while, and I would imagine it's comparable to most PDAs.

STD is suspend-to-disk, which is the SD card(s) in this case, and that can last indefinitely long (since the device needs no power in this mode).

Of course, it's best to charge the battery to 40% or so and turn it off, if you know you won't be using the device for a month or more...

 

[mannowhere]

Ahh, thank you for the definitions -- while I've heard/read those phrases in the past, I'm more used to just "suspend" for the former and "hibernate" for the latter. Perhaps that's my Winbloz background rearing its ugly head again...

 

[Squidge]

Any way of determining that for certain before I commit to this device? I would imagine that such a feature would also be important to many other users for whom Pandora's potential as a PDA ranks high among their

That's probably a question for MJW, who's the hardware designer. Try sending him a PM.

 

[IceBerg303]

It will be nice to see what the battery performances are on the display off and suspend to ram are in comparison. Obviously this will vary with what else is running but once we get Pandora in our hands I'm sure some reasonable comparisons can be made, and hell we can even annoy our finds and family buy playing some hideous Britney spears song on repeat till the battery dies and be the only ones with ear plugs to block it out.

None the less I would like to be able to use some PIM/PDA app with alarms and screen off seems like the ideal mode for that. As to my knowledge there is no built in alarm circuit for wake on alarm and it doesn't make sense on something who's primary vision was for games.

On another note on page 1 of this thread someone mentioned Pandora moving at the speed of light to conserve battery life. NOTE, at this point you can quit reading as Im drunk and going to babble a little about science.

First of all, which speed of light? Because if were talking about the speed of light as it escapes the near edges of the event horizon of a black hole, then the battery would die faster than average.

If we are talking the average speed of photon radiation in the vacume of empty space the the problem becomes that apps would run to fast to be usable, but you could get some killer billions of frames per second doing real time fractal plotting of prime numbers with numbering digits higher than 100,000. You could also crack the IRS DBase in seconds and be just like Trinity. But then you would have to kiss Keanu Reeves and no one wants that.

Anyway the point was that the comment about the speed of light wasn't funny like it was intended for the simple reason that the speed of light is relative to the medium in which it travels in. Scientists are beginning to cease use of measurements against the speed of light and use real world measurements instead.

Ok, I'll go pass out now.