[Tinyos-host-mote-wg] RE: [Tinyos-2.0wg] TinyOS Telecon Notes 8/31/05

[mturon at xbow.com]

Hi Joe,

The internal oscillator is default for low-power apps.  This opens up a
discussion on initialization of timers.  

We need to think about timer initialization and how to allow multiple
configurations.  Some users will want to set an MCU to a different clock
speed.  What API do we use to specify this?

Martin 
__________________________________________________
Martin Turon  |  Crossbow Technology, Inc.

-----Original Message-----
From: Joe Polastre [mailto:joe.polastre at gmail.com] 
Sent: Thursday, September 01, 2005 4:29 AM
To: Ben Greenstein
Cc: mturon at xbow.com; tinyos at barnowl.org
Subject: Re: [Tinyos-2.0wg] TinyOS Telecon Notes 8/31/05

> Phil: I agree. It should take something like 60-80 cycles to compute
> the power state of the mcu. Let's consider the notion of a dirty
> bit. If anything changes in the power state, the dirty bit isset. The
> MCU goes into same state as the last time unless this bit is set. When
> set it recomputes. ... Is this notion something that would be usesful
> for eyes?

Note about Phil's comment:

This won't work if you're using a DMA or other such device that relies
on other hardware components.  It makes setting the "dirty" bit very
difficult.

Besides, 60-80 cycles is at most 20us of computation.  Considering it
takes longer than that for the Atmel to wake up, I don't see a problem
doing the computation.

Martin-- What is going to be the "default" oscillator for mica2 and
micaz?  Seems like using the external oscillator is like shooting
yourself in the foot before you even start.  Does Xbow have any plans
to calibrate the internal Atmel oscillator?  Is there even a reason to
include the external oscillator on the board?  Obviously we don't use
one on Telos/Tmote or Eyes, and there's at least one "micaz clone"
that don't have it either.

-Joe


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