Bug #1024 (oscillating re-camping), a possible solution.

Nils Faerber nils.faerber at kernelconcepts.de
Wed Jun 10 19:37:58 CEST 2009

Daniel Willmann schrieb:
> Hi,

> On Fri, 29 May 2009 22:58:53 +0200
> Joerg Reisenweber <joerg at openmoko.org> wrote:
>> Last not least: probably a better battery management will have more
>> positive effects on standby time than fixing #1024 in hw and using
>> AT%sleep=4 all the time. First raw estimations seem to suggest
>> there's an increase in standby time from maybe 60h with sleep2 to 75h
>> with sleep4. If your standby time is shorter than these figures then
>> even percentage of difference gets *smaller* (e.g. like 20h vs 21h =
>> 5%, instead of 60/75 = 25%), due to savings from sleep4 becoming
>> negligible compared to higher suspend consumption of whole system.
> I ran a battery consumption test on my #1024 fixed freerunner, the
> results of which can be seen here:
> http://totalueberwachung.de/blog/2009/06/03/freerunner-deep-sleep-standby-time
> I got close to 6 days worth of standby time (143h) which I found rather
> impressive. The phone was not used at all for calls so the value
> represents an upper limit, but I checked that the GSM modem was still
> operational by calling the device at the end. I'm currently repeating
> the test once more and will post an update once it's done, but it seems
> we'll be in the 130-140h region again.

Wow - that seems pretty much to me.
That would mean an average of 8.39mA current consumption given that the
battery really has 1200mAh. This *is* little - the system standby
current should be around 2-4mA so this leaves just 4-6mA for the modem.
This is IMHO good.
Currently on an unreworked GTA02 I see (last time I checked) about 15mA
standby with additional peaks (presumably the modem wakeups). 8mA is
again almost half of it which cannot be only due to the capacitor.

So which software(-distribution/kernel) have you been running to do the
test? I this is critical to know in order to see which devices e.g. were
powered or not etc.
If thos results can be reproduced then this really means a major step
forward! 130-140h standby time is pretty much the same as you can expect
from a WinMobile Smartphone or any other similar GSM/3G device (while
the 3G usually eat more battery).

> Regards,
> Daniel Willmann
  nils faerber

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