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Subject: Re: games/demos cost on play buffer?
From: Rob Ward (
Date: 2002-12-13

40mA seems like a lot when in some shutdown mode. Many new
microprocessors are down in the low microamp range.


Daniel Stenberg wrote:

>On Fri, 13 Dec 2002, George Michaelson wrote:
>>Extrapolating from this, I infer that the in-memory cost of games and demos
>>has to be marginal as well, ie if one imagined building a version of the
>>code without them, the increased memory would give <5% extended battery
>>life if the memory saved was measured as 1Mb (unlikely?). for a 10hr
>>battery life, thats 30min extra play. For me, thats on the cusp of being
>>worth it. But since I expect the SH3 codesize is dense, and so the saved
>>memory will be smaller, the net increase in battery life begins to look
>>marginal (this is only theory: until I make my build env with a gcc-sh3, I
>>can't say what the cost is)
>It is an SH1, SH7034. And I'd guess that the size of all games together is
>more like in the area 30-50 KB or so. It would be easy to check.
>>What other things tend to improving battery life? The backlight costs and
>>LCD update also look to be marginal savings at this time.
>Not much more can be done, AFAIK. We can verify that we're using the best
>possible ATA code that keeps the power consuption at its lowest. We can work
>on using the CPU SLEEP mode to reduce power even more, but it requires some
>neat hacks.
>Björn and I were talking the other day about adding a mode where we shut down
>all external circuits and go to SLEEP. That would bring us down to almost
>40mA power consumption and thus we could get a "wake up" function that could
>survive ~40 hours on 1600mAh batteries.
>It could for example be used as an alarm clock, or to make it survive a night
>in the car until you start it again next morning and charges your Archos
>again. Etc.
>Of course we have no code for this at this point. We were only dreaming of
>new and better worlds! ;-)

Page was last modified "Jan 10 2012" The Rockbox Crew