Hi, Anybody here tried to calibrate the 1-wire temperature sensors additional to the factory calibration? Only reference I've found sofar is this one: http://yosemitefoothills.com/Thermometers/ThermometerCalibrations.html
At the moment I've got 30 DS18B20 measuring inside a glass jar in a little box of polystyrene foam with water and ice. Connected to a Raspberry Pi which takes a measurement of all the sensors every 2 minutes. This takes about 30 seconds. After 8 hours the water is still pretty cold in a room which is approximately 20°C. Measurements: http://nl.tinypic.com/r/2mz9wed/8 The results are a little spiky. That's probably the resolution of the sensors? Can this be changed? Or do I have to take an average over 5 measurements the smooth things a bit? When using the average of the 30 sensors as being the "true" temperature, I can use regression analysis to compensate each sensor. Sofar i've found that linear regression (-0,04 / +0.06) gives me a better fit then quadratic regression (-0,14 / +0,25). Probably because of the small range of the temperature at the moment. Linear: http://nl.tinypic.com/r/2u8ur1w/8 Quad: http://nl.tinypic.com/r/23wpeme/8 How can one identify the sensors? Is the id code written on the DS18B20 itself? Or do I have to plug them in one at the time to ID them? Kind regards, Joris Meijerink ------------------------------------------------------------------------------ _______________________________________________ Owfs-developers mailing list Owfs-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/owfs-developers
