[Tinyos-help] [Tinyos-devel] Dirty bit reset

Vlado Handziski handzisk at tkn.tu-berlin.de
Mon Nov 29 02:27:52 PST 2010


Hi,

the dirty bit is an optimization mechanism that helps avoid
unnecessary re-computation of the lowest safe power state of the MCU. In
most of the current implementations, this computation is quick and the bit
is assumed to be always TRUE, i.e. the low power state is recomputed every
time the MCU can go to sleep. That is why you don't see it being "reset" in
the existing McuSleep.sleep() implementations.

Vlado

P.S. Please don't cross-post to -devel even if you don't get an quick answer
on -help :)


On Mon, Nov 29, 2010 at 08:50, Romain Bornet <bornet.reds at gmail.com> wrote:

> Hi all,
>
> I'm rather new in TinyOS and I'm currently working on a port to a new
> architecture and am therefore carefully reading TEPs and intensively looking
> into other architectures implementations.
>
> I cannot understand the handling of the "dirty bit" used in power
> management. The dirty bit mechanism is described in TEP112 (
> http://www.tinyos.net/tinyos-2.1.0/doc/html/tep112.html) section 3.1 but I
> could not find in TOS sources where this "flag" is reset !
>
> I could see that the flag is set to 1 or TRUE for some MCUs in chips
> directory but could not find any place in the whole sources where this flag
> gets reset ?... (some cale in msp430/McuSleepC.nc have a commented '// dirty
> = 0' in McuSleep.sleep()
>
> - Is this flag really useful and used in TinyOS 2.1 ?
> - If yes, how/when should this flag be reset ?
>
> I posted without any success to the help list a week ago so perhaps I will
> be luckier in the "devel list".
>
> Thanks for any hint and see you !
>   Romain
>
>
>
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