[Tinyos-help] Re: [Tinyos-devel] DAC and MSP430RefVoltGenerator in T2

John Griessen john at ecosensory.com
Thu Feb 14 13:26:20 PST 2008


I like Sandip's idea to create an arbiter that reserves use of refvolt to the first
process that asks, but also responds to queries about the refvolt value.

Do arbiters as they are now allow for keeping a queue of asking routines satisfied
with a resource with no breaks?

Would a shared arbiter for DAC and ADC be able to handle both these cases:
1.  ADC is claiming a resource for a longer time than DAC asks for it, responds with volt value,
         DAC runs and stops before  ADC stops, and ADC keeps using it uninterrupted?
2.  ADC asks for a resource, then DAC asks for it, and starts sharing it,
          ADC stops and releases resource in a way that DAC keeps using it uninterrupted?


> ----- Original Message ----
> From: Jan Hauer <hauer at tkn.tu-berlin.de>


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
> 

I have a third alternative, so it's not stopping me completely from going ahead.

To get my soil moisture sensors supplied
with 2.500 +/- .005 Volts, I could create a PWM DAC and use a program to adjust it to
2.50 V, but it seems useful to have more options.

John Griessen

-- 
Ecosensory   Austin TX
tinyOS devel on:  ubuntu Linux;   tinyOS v2.0.2;   telosb ecosens1


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