Hi, The formula in the internal temperature sensor module might refer to the value you'd get when sampling the temperature sensor internal to the msp430 microcontroller. For the two SHT11 formulas, I have no idea what the second formula refers to, the first one seems to be the one from the data sheet (page 9):
http://www.sensirion.com/en/pdf/product_information/Datasheet-humidity-sensor-SHT1x.pdf Depending on how exact the value should be, you can also measure and compensate for the actual battery voltage. If you have the mote plugged into a USB port, beware that the on-board voltage converter generates some heat, which in turn falsifies the reading (by up to 1 degree Celius). Cheers, Urs On 11/13/11 5:41 PM, Geo Gkolfin 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 > > > > _______________________________________________ > Tinyos-help mailing list > Tinyos-help@millennium.berkeley.edu > https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help _______________________________________________ Tinyos-help mailing list Tinyos-help@millennium.berkeley.edu https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
