Power management concept...

Ian Stirling openmoko at mauve.plus.com
Tue Apr 24 13:55:28 CEST 2007

Nils Faerber wrote:
> 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.

Uses several (3-5) times more power per MIP than fast mode.
USB does not work, so no bluetooth.
LCD controller does not work, so no display (unless as I've speculated, 
the LCD - as some can, can be written from the SPI bus).

CPU alone in slow mode uses some 1/3 of the battery per day.

Things that are possible - GPS, GSM, audio in/out (though there is not 
enough CPU to decode OGG/MP3/...).

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.

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