Hi Georgia,

This is not an internal temperature sensor, it's a Sensirion SHT21
Humidity/temperature sensor, so you should use the formula from its
datasheet: 
http://www.sensirion.com/en/pdf/product_information/Datasheet-humidity-sensor-SHT1x.pdf


Andris

On Sun, Nov 13, 2011 at 5:41 PM, Geo Gkolfin <[email protected]> wrote:
> Hello!
> I am trying to sample the internal sensor of a telosb mote.
> At TempC.nc I have
> module TempC{
> ...
> uses interface Read<uint16_t> as Temp;
> ...
> }
> and at TempAppC.nc
> implementation{
> ...
> components TempC;
> components new SensirionSht11C() as Temp;
> ...
> TempC.Temp->Temp.Temperature;
> ...
> }
> In TempC.nc I call read() and I print the uint16_t data returned by
> Temp.readDone.
> It is about 6200. In order to convert this value to Celsius I follow the
> instructions given in
> tinyos-2.1.0/tos/chips/msp430/sensors/Msp430InternalTemperatureC.nc
> I multiply the value with 1.5 and I divide the result by 4096. Then I
> subtract 0.986 and I divide with 0.00355.
> Unfortunately this formula return a huge value, about 350. No way my room is
> that hot! :-)
> On the other hand I found
> (http://www.eecs.iu-bremen.de/wiki/index.php/TinyOS) the following
> conversions formulas:
> -40+0.01*data and
> -38.4+0.0098*data
> Those give nicer results, but...which one should I use? Neither of them give
> the exact same result as my thermometer but they are both quite close. And
> why the conversion formula given in Msp430InternalTemperatureC.nc does not
> work?
> Thank in advance,
> Georgia
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