[Tinyos Core WG] Meeting: 5/30

[Kevin Klues]

> For example, on the
> msp430 ADC the HAL client "Msp430Adc12ClientC" provides the
> "Msp430Adc12MultiChannel" interface which does exactly what we are
> talking about. A simple wrapper could map this to a "HIL" without the
> need for a GroupedSensorsP that "cycle(s) through 'numSensors'
> requests in a for loop for all connected Resource interfaces, waiting
> for them all to be granted before issuing a read() command on all of
> them concurrently."



The idea behind the GroupedSensors component is for grouping multiple types
of sensors together -- not just those that rely on access to the ADC.  Its a
way of ensuring that the sensor reading you take are correlated in time in
some way.  For example, on the telos, you can issue commands to sample the
humidity and photo sensors concurrently, but you can't do the same for
humidity and temperature -- these have to be sampled serially since they
require access to the same hardware chip.

GroupedSensors would just be a way of conveniently specifying which sensors
you want to take samples from together so you don't have to mess with
grabbing hold of resources and managing the state required to sample
multiple sensors at once.

In regards to sampling sensors (2,5,6) obviously these would need to be
mapped to some platform specific (or sensorboard specific) sensor
identifiers... you wouldn't just use the raw numbers themselves.

Kevin
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