On Thu, 21 Sep 2000, Jamey Hicks wrote:
> There are several interesting power levels we should at least think about
> implementing:
> 1) active devices turned on, full speed CPU clock
> 2) StandbyH: processor clock slowed, LCD off
> 3) StandbyL: all peripherals turned off
> 4) Suspend: active DRAM flushed to flash or other storage,
> CPU and DRAM halted, all peripherals off
> - requires firmware support, lack of real-time-clock an issue
> 5) Off: kernel must reboot
> I think we can do (1) and (5) now. I would like us to implement (2) and
> (3). I'm not sure (4) is worth the effort -- we'll have to measure power
> consumption in the standby states. WinCE gets at least a week of battery
> life without implementing 4.
I agree as far as 1,2,4 and 5 are concerned.
I think 3 can be made much niftier. Just turning off all peripherals is not not
all we can do. Follwing idea:
- we know where the kernel lives and which parts of RAM it is using. We should
be able to put the rest to self-refresh mode (AFAIK this is possible with DRAM
and conserves power).
- the CPU should be clocked at it's lowest speed, or:
- put the CPU into standby mode. But we will have a problem with the date/time
clock since there is no real time clock to sync against when we leave standby.
Isn't there any timer that could be used to interrupt the standby at a fixed
time interval to update the clock?
> -Jamey
nils faerber
-- kernel concepts Engel & Faerber GbR Tel: +49-271-771091-12 Dreisbachstr. 24 Fax: +49-271-771091-19 D-57250 Netphen D1 : +49-170-2729106 --Received on Thu Sep 21 07:02:01 2000
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