I have similar problems, but i got a value which is some celsius degree above
the real temperature. My code is:
System.out.println("ADC Value " + average);
final double a = 0.00130705;
final double b = 0.000214381;
final double c = 0.000000093;
double Rthr = ( 10000.0 * (1023.0 - average )) / (double)average;
System.out.println("Rthr " + Rthr);
double logRthr = Math.log(Rthr);
double inverseKelvinTemp = a + b * logRthr + c * (logRthr * logRthr * logRthr);
System.out.println("Inverse Kelvin " + inverseKelvinTemp);
double celsiusTemp = 1.0 / inverseKelvinTemp - 273.15;
when the temperature is around 20 or 22 celsius degrees i got 29 or 30 celsius
degrees.
>From the MTS and MDA manual i see that the constants are different among
>different sensor board. I use the XBow MTS310CA sensor board
Mario
________________________________
Da: [EMAIL PROTECTED] per conto di Yanchuan Li
Inviato: mer 14/05/2008 23.13
A: tinyos-help@millennium.berkeley.edu
Oggetto: [Tinyos-help] About Temperature
Anyone knows how to convert a ADC reading into real Degrees for temperature?
On the Manual, it's said like following:
The mote's ADC output can be converted to degrees Kelvin using the following
approximation over 0-50 °C: 1/T(K) = a + b × ln(Rthr) + c × [ln(Rthr)]3
where:
Rthr = R1(ADC_FS-ADC)/ADC
a = 0.00130705
b = 0.000214381
Page 10 Doc. # 7430-0020-03 Rev. B
MTS/MDA Sensor Board User's Manual
Wireless Sensor Networks
c = 0.000000093
R1 = 10 k?
ADC_FS = 1023
ADC = output value from mote's ADC measurement.
BUT I always got readings like between 500-600. And when I using the function
above, I got some really weird numbers after calculation.
double a = 0.00130705;
double b = 0.000214381;
double c = 0.000000093;
double r1 = 10;
double adc_fs = 1023;
double adc = 600;
double rthr = (r1 * (adc_fs - adc))/adc;
double temp = Math.log10(rthr);
double temp1=Math.pow(temp, 3);
double temp3=a+b*temp+c*temp1;
System.out.println(1/temp3);
RESULT: 671.6176617203942
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