[Tinyos-devel] DAC and MSP430RefVoltGenerator in T2

[Jan Hauer]

Currently Msp430RefVoltArbiterImplP intercept the requests of ADC
clients to the Resource interface, it is not really arbitrating access
itself. If the DAC needs access to the RefVolt component too, then we
might need a real arbiter for the RefVolt component that is
independent of the actual ADC arbiter. The drawback is then that for
every ADC/DAC request involving RefVolt we'd need to request two
resources from two different arbiters before the client can start
sampling/outputting. Alternatively we could agree that ADC and DAC
share the same arbiter, which makes arbitration a lot easier, but is
less efficient because you'd never be able to run ADC and DAC in
parallel.
Jan



On Wed, Feb 13, 2008 at 7:53 PM, Vlado Handziski
<handzisk at tkn.tu-berlin.de> wrote:
> The access to the refvolt generator has to be properly arbitrated between
> the ADC and the DAC. Pins, timers, etc. are all potential shared resource
> between the two. Jan, who is responsible for the msp430 ADC stack, is at a
> project meeting and probably has not read the thread. Please get in touch
> with him to coordinate. No #ifdefs please :)
>
> Vlado
>
>
> On Wed, Feb 13, 2008 at 6:43 PM, John Griessen <john at ecosensory.com> wrote:
> >
> >
> > Sandip Bapat wrote:
> >
> >  a DAC module would either have to wire to Msp430RefVoltArbiterP (in which
> case it also has to provide the
> >
> > AdcConfigure interface) or be expected to provide wiring for these
> interfaces.
> >
> > This is fine for apps that just want to use the DAC and not ADC but what
> if both are used and the
> >
> > ADC is already using Ref Voltage ? I guess we could use #ifdefs in the DAC
> but wouldn't having
> >
> > a Msp430RefVoltArbiterC that does the wirings required for
> Msp430RefVoltGeneratorP be better?
> >
> > The best thing would be to create new function in the RefVoltArbiter so it
> can stay on after an ADC12 or
> > Dac12 call has requested it if another request is heard within a time
> period.  As far as I can tell,
> > Dac12 and Adc12 of a MSP430F1611 can both be going at once.
> >
> > John Griessen
> >
> >
> > --
> > Ecosensory   Austin TX
> > tinyOS devel on:  ubuntu Linux;   tinyOS v2.0.2;   telosb ecosens1
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> >
> >
>
>