Power management concept...

Ian Stirling openmoko at mauve.plus.com
Tue Apr 24 15:03:02 CEST 2007

Nils Faerber wrote:
> Ian Stirling schrieb:
>> Nils Faerber wrote:
>> <snip>
>>> Personally I would be much more interested in slow-mode than in
>>> suspend/power-off. As I described it would allow (slow) applications
>>> running all the time without much power consumption. This would be a
>>> very interesting feature.
>> Annoying things about slow mode.

>> LCD controller does not work, so no display (unless as I've speculated,

> And touchscreen I guess.

I think that touchscreen actually works.

>> It may well in many applications be better to - if it can be done
>> rapidly - suspend to RAM for 5 seconds and wakeup for 1 second, in fast
>> mode, repeatedly, rather than sitting in slow mode.
>> This probably uses less power, and you can use the bluetooth module when
>> you are awake.
> Hmm... I can remember the older iPaq devices to do "short" wakeups for
> checking battery state while charging. In this case the device did not
> resume completely but only wake-up the CPU and SDRAM to check some
> states and go to sleep again immediately afterwards.
> Then this is probably a better approach if the slow mode consumes that
> much power...

It depends how fast resume from RAM is.
For 'normal' use - modem sends RING signal, CPU wakes up, and starts 
ringing the speakers - a second or two delay doesn't really matter.
For repeatedly waking up, doing stuff, going to sleep, it starts to 
really matter, as every millisecond you are waking up is a millisecond 
you're not asleep using no battery.

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