[Tinyos-devel] Request for comments: TEP 112

[Vlado Handziski]

Traditionally the 32khz timer (timerB) on the msp430 platforms has been kept
always running, hence this long standing convention to default to LPM3. We
can definitely remove this sentence from the TEP. The removal of the actual
default LPM3 in the getPowerState() implementation will be done once the
timer arbitration refactoring is completed, i.e. after the 2.1 release.

Vlado

On Fri, Jun 13, 2008 at 18:32, David Moss <dmm at rincon.com> wrote:

> "For example, the MSP430 defaults to low power mode 3 (LPM3) unless it
> detects that Timer A, the USARTs, or the ADC is active, in which case it
> uses low power mode 1 (LPM1)."
>
> There's a problem with this wording and implementation. If all timers are
> inactive, the MSP430 implementation should default to LPM4. This saves you
> ~5-10x more energy than LPM3.
>
> Two reasons:  1. TinyOS is a generic operating system that doesn't require
> Timers to operate.  2. Wake-on Radio.
>
> Here are a few applications that use LPM4:
>
> http://focus.ti.com/lit/an/slla175/slla175.pdf
> http://focus.tij.co.jp/jp/lit/an/slaa384/slaa384.pdf
> http://www.gaw.ru/pdf/TI/app/msp430/slaa119.pdf
>
> Yes, it takes the microcontroller longer to wake up that crystal in LPM4.
> Whether you care or not depends on the end application.  For wake-on radio
> type applications, I don't care. For a TV IR remote or interrupt-driven
> system, I don't care. I just want the microcontroller in the lowest power
> state possible, which is LPM4.  For other applications that need a faster
> response time for an external interrupt while no timers are running
> anywhere
> in the application, the McuPowerOverride interface is available and
> documented.
>
> -David
>
>
>
>
>
>
>
>
>
> -----Original Message-----
> From: tinyos-devel-bounces at millennium.berkeley.edu
> [mailto:tinyos-devel-bounces at millennium.berkeley.edu] On Behalf Of Prabal
> Dutta
> Sent: Thursday, June 12, 2008 2:28 PM
> To: tinyos-devel at millennium.berkeley.edu
> Subject: Re: [Tinyos-devel] Request for comments: TEP 112
>
> Just a reminder that tomorrow is the last day for comments on TEP 112.
>  If you have some thoughts but haven't sent them in, please take a few
> minutes and send them to me today or tomorrow.  I will consolidate the
> feedback and work with the authors.  Thanks again for your
> participation in this important process.
>
> - Prabal
>
> On Fri, May 30, 2008 at 11:26 AM, Prabal Dutta <prabal at cs.berkeley.edu>
> wrote:
> > Dear TinyOS Developers,
> >
> > I have been asked to shepherd TEP 112 (Microcontroller Power
> > Management) through the Community Review process.  This TEP documents
> > how TinyOS manages the lower power state of a microcontroller in
> > TinyOS 2.x.  Microcontrollers often have several power states, with
> > varying power draws, wakeup latencies, and peripheral support. The
> > microcontroller should always be in the lowest possible power state
> > that can satisfy application requirements.  Determining this state
> > accurately requires knowing a great deal about the power state of many
> > subsystems and their peripherals.  Additionally, state transitions are
> > common.  Every time a microcontroller handles an interrupt, it moves
> > from a low power state to an active state, and whenever the TinyOS
> > scheduler finds the task queue empty it returns the microcontroller to
> > a low power state.  TinyOS 2.x uses three mechanisms to decide what
> > low power state it puts a microcontroller into: status and control
> > registers, a dirty bit, and a power state override.  TEP 112 documents
> > these mechanisms and how they work, as well as the  basics of
> > subsystem power management.
> >
> > Getting feedback from other TinyOS developers is an essential part of
> > the TEP process and I am looking for volunteers to read the draft TEP
> > and provide feedback to me via e-mail.  I will then synthesize the
> > comments and work with the authors to revise the TEP based on your
> > feedback.  Getting feedback by June 6th would be ideal.  The hard
> > deadline is June 13th.
> >
> > The current draft of the TEP is linked from the TinyOS homepage:
> >
> >
>
> http://tinyos.cvs.sourceforge.net/*checkout*/tinyos/tinyos-2.x/doc/html/tep1
> 12.html<http://tinyos.cvs.sourceforge.net/*checkout*/tinyos/tinyos-2.x/doc/html/tep112.html>
> >
> > Please contact me by email directly at prabal at cs dot berkeley dot
> > edu if you have some feedback.  Thanks for your help!
> >
> > - Prabal
> >
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