[Tinyos Core WG] Issue with sampling multiple sensors

[Vlado Handziski]

I fully agree with Jan. If someone needs this level of performance, then
they should use HAL level abstractions. That is the reason why they are
there. Otherwise, we could have had monolithic implementations of the HIL
abstractions.

Vlado

On 5/23/07, Jan Hauer <jan.hauer at gmail.com> wrote:
>
> > > ("I can't sample X&Y acceleration at more than 31Hz!") brings up a
>
> This is the price for the HIL abstraction, if someone needs better
> performance then they have to go via the HAL. For example, the msp430
> HAL has the "Msp430Adc12MultiChannel" interface for sampling multiple
> sensors "at once". In my understanding when Read[Stream|Now] are used
> for sensing they are best-effort as a comprise between the different
> platforms. If we wanted yet another abstraction not only TEP 109
> (Sensorboards) would need to be changed, but probably also TEP 101
> (ADC), which is already finalized.
>
> Jan
>
> On 5/22/07, Kevin Klues <klueska at gmail.com> wrote:
> > What would be nicer still is some declarative way of saying which
> > sensors you want and at which rates, and to let the proper code be
> > generated for you...
> >
> > Kevin
> >
> > On 5/22/07, David Gay <dgay42 at gmail.com> wrote:
> > > The thread that starts with
> > >
> http://mail.millennium.berkeley.edu/pipermail/tinyos-help/2007-May/024986.html
> > > ("I can't sample X&Y acceleration at more than 31Hz!") brings up a
> > > limitation of ReadStream:
> > > how can one sample a group of sensors at high rates?
> > >
> > > It's easy enough to sample one sensor at a high rate, or several
> > > sensors in succession. But if I want 200Hz sampling of X&Y
> > > acceleration simultaneously, there doesn't seem to be a very good
> > > answer?
> > >
> > > Possible current solutions:
> > > - go low level, using Resource to reserve both sensors and ReadNow to
> > > sample them (i.e., do ReadStream by hand) - this requires the
> > > sensorboard to make *Now versions of each sensor available (the mts300
> > > doesn't...)
> > >
> > > - have the sensor provide all reasonable sensor groups (e.g., X, Y and
> > > X&Y) - painful for more than two sensors
> > >
> > > Possible future solutions:
> > > - some interface to sampling groups of sensors? could be icky...
> > >
> > > Anyway, something I noticed from that thread rather than any good
> answer.
> > >
> > > David
> > > _______________________________________________
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> > >
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> > >
> >
> >
> > --
> > ~Kevin
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> >
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