[Tinyos-help] Photo sensor on telosb ( tinyos-2.x )

[Michael Schippling]

Assuming that you covered the sensor or shut off the lights in the
middle of that data sequence you may actually be getting good data.
Usually a low value would be dark and a high value light.

The values themselves would probably be raw ADC readings and thus
some fraction of the battery voltage (which is used as the reference).
The telos's have a 12 bit converter so you're probably looking at
1113/4096's * 3.3 volts.

I believe there are some guidelines for converting the readings to
engineering units in the tmote sky user manuals, but the Hama chip
spec sheet should have some information as well.

MS


hukang wrote:
> Dear All:
> I am working on Tinyos-2.x using telosb and need the data from the
> onboard sensor HamamatsuS1087. Since the DemoSensorC in 2.x is not wired
> to HamamatsuS1087, I have to modify it as follows in Oscilloscope.
> {
>      //new DemoSensorC() as Sensor,
>     , new HamamatsuS10871TsrC() as Sensor
>     ...
>     OscilloscopeC.Read -> Sensor;
> }
> Then I got the returned values by java net.tinyos.tools.Listen like
>  03 E8
>  04 45
>  04 59
>  04 45
>  04 47
>  04 39
>  00 02
>  00 02
>  00 02
>  00 03
>  00 02
>  00 01
>  00 04
> Converting to decimal the brightest is 1113 (04 59) and the darkest is 1
> (00 01). Does anyone know if these data are valid?
> And what is the unit of these value. is it Lux? Thanks.
> 
> Steven
> 
> 
> 
> 
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-- 
Platform: WinXP/Cygwin
TinyOS version: 1.x, Boomerang
Programmer: MIB510
Device(s): Mica2, MicaZ, Tmote
Sensor board: homebrew