[Tinyos-devel] Request for comments: TEP-108

[Jan Hauer]

> Correct me if I'm wrong (Jan, David, Gil), but sensorboard
> implementations are built on top of the ADC resource which should
> expose the Resource/ResourceRequested interfaces along with the
> ReadNow interface from the ADC HIL.

The ADC HIL provides ReadNow with an instance of Resource, not with
ResourceRequested. TEP 108 says "An arbiter SHOULD provide a
parameterized ResourceRequested interface to its clients, but is not
required to." The ADC does not (and we agreed it should not) specify
which exact arbiter is used. Since the ADC HIL cannot expect that
there is a ResourceRequested, it does not provide this interface.

Miguel, what about writing *one* component that provides you access to
both sensors, built on top of the ADC HIL (the component keeps some
state/timer about the current configuration and waits 10ms if needed;
you might even use a power manager or can have a look at the reference
voltage generator code for msp430) ?

Jan

> A sensorboard that uses an ADC
> should connect through this HIL interface in order to implement its
> SIDs interface.  Maybe the ADC HIL implementations haven't been
> updated yet to expose this interface as it is still under discussion.
> (I know that TEP 101 currently says that ReadNow is only provided in
> conjunction with Resource, but maybe it needs to be updated....
> again....).

> > > 1. check if isOwner(), proceed with ADC conversion if true and go (5).
> > > 2. if not owner, request() resource.
> > > 3. on granted(), start a 10ms timer.
> > > 4. on timer's fired(), proceed with ADC conversion.
> > > 5. do not release resource.
> > > 6. on requested() event, call release()
> > >
> > > this way, every time the resource is changed between sensors i would
> > > have the 10ms delay. consecutive reads to the same sensor do not need
> > > to use the timer.

On 11/6/06, Kevin Klues <klueska at gmail.com> wrote:
> These aren't so much comments on the contents of the TEP, but rather
> on how to use the features it presents.  Implementations of Arbiters
> according to the TEP exist in the development branch of cvs on
> sourceforge, but not on the main branch.
>
> Correct me if I'm wrong (Jan, David, Gil), but sensorboard
> implementations are built on top of the ADC resource which should
> expose the Resource/ResourceRequested interfaces along with the
> ReadNow interface from the ADC HIL. A sensorboard that uses an ADC
> should connect through this HIL interface in order to implement its
> SIDs interface.  Maybe the ADC HIL implementations haven't been
> updated yet to expose this interface as it is still under discussion.
> (I know that TEP 101 currently says that ReadNow is only provided in
> conjunction with Resource, but maybe it needs to be updated....
> again....).
>
> One thing to note, however, is that using the ResourceRequested
> interface alone in order to decide when to release a resource is
> discouraged for devices that wish to use the power management features
> available with T2.  If clients only release resources based on a
> ResourceRequested event, then the resource will never have the chance
> to go idle and any power managers wired to the ResoruceController
> interface provided by the resource's arbiter will not be able to power
> it on/off automatically.  In the case of the ADC on the Msp430, this
> means that the reference voltage generator never has the chance to go
> off even though there are no users currently using the ADC (not sure
> what the repercussions are for the atmel platforms).
>
> I think what is typically done is that the SIDs read interface is
> implemented using the ADC HIL Read interface and the SIDs ReadStream
> interface is implemented using the ADC HIL ReadStream interface so
> that you don't have to worry about the details of dealing with the
> Resource yourself unless it is specifically required for your
> implementation (that's why the ReadNow interface exists).  The
> sensorboard implementation thus takes care of configuring the ADC
> correctly and then calling its respective Read and ReadStream
> implementations....
>
> Kevin
>
> On 11/6/06, Miguel Freitas <mfreitas at gmail.com> wrote:
> > Hi Kevin,
> >
> > On 11/5/06, Kevin Klues <klueska at gmail.com> wrote:
> > > Dear TinyOS developer community:
> > >
> > > Matt Welsh sent out a request for comments on TEP 108 on October 20th.
> > >  Until now no one has responded to this request, and the deadline
> > > before  the TEP moves into final review is November 17th.
> >
> > I'm a newcomer here, so please take my comments with a grain of salt.
> > I have replied Matt directly with both comments and questions, below
> > is the email i've sent him.
> >
> > ---
> >
> > On 10/31/06, Miguel Freitas <mfreitas at gmail.com> wrote:
> > > Matt,
> > >
> > > I'm investigating the porting of the mts300 sensorboard to latest
> > > tinyos-2.0 standards, and resource arbitration is a key point.
> > >
> > > i have 2 sensors sharing a single resource (the same adc channel). to
> > > make things more fun, the original mts300 code implemented a 10ms
> > > delay after changing adc source as a matter of "stabilization" of the
> > > signal.
> > >
> > > my plan for implementing this would be using the Resource /
> > > ResourceRequested interfaces. for example:
> > >
> > > implementation of the command "read()" of one of the sensors:
> > >
> > > 1. check if isOwner(), proceed with ADC conversion if true and go (5).
> > > 2. if not owner, request() resource.
> > > 3. on granted(), start a 10ms timer.
> > > 4. on timer's fired(), proceed with ADC conversion.
> > > 5. do not release resource.
> > > 6. on requested() event, call release()
> > >
> > > this way, every time the resource is changed between sensors i would
> > > have the 10ms delay. consecutive reads to the same sensor do not need
> > > to use the timer.
> > >
> > > the problem is: requested() event is only available from
> > > ResourceController which is a single instance on arbiters. there is no
> > > such thing called ResourceRequested on tinyos cvs.
> > >
> > > what should i do?
> > >
> > > is that TEP waiting for general agreement before ones starts coding
> > > support for ResourceRequested?
> > >
> > > am i trying a wrong/bad/stupid solution for this problem?
> > >
> > > Miguel
> > >
> >
>
>
> --
> ~Kevin
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