Accelerometer question

Andy Green andy at openmoko.com
Fri Oct 10 09:33:19 CEST 2008


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Rui Miguel Silva Seabra wrote:

> 	The rate at which they feed me data only starts up when the file
> 	handle is opened, and stops when it's closed?

This is the case, the interrupts are quenched when no file handles are
open on them.

> I'm just wondering, because my 1 year old Nokia 2670 just lasted a whole
> week in idle on an 700mAh battery, and OpenMoko lasts only about 8/9
> hours in idle with a 1200mAh battery. It is nuts, we all know that, but
> I'm more interested right now into extending battery life, as it is my
> single greatest problem with OpenMoko right now.

The issue is "what does idle mean".  Suspend for Freerunner should last
a week.  Sitting there with CPU up even with backlight down is 60-90mA
on battery, suspend is 5 - 10mA and that's why you get battery life
reduced accordingly if you stay out of suspend.  That's a kernelspace
issue on the one hand (suspend is not entirely reliable) but also a
userspace issue (there have been bugs negotiating entry to suspend
instead of sitting there with CPU up at 400MHz and backlight down).

- -Andy
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