TemperatureSensor.cpp

00001 #include <TemperatureSensor.h>
00002 #include <math.h>
00003 
00004 TemperatureSensor::TemperatureSensor():adc(p20) {
00005     percentOfScale= adc.read();
00006 }
00007 
00008 void TemperatureSensor::measure(void) {
00009     static const float R= 10500.0;
00010     static const float LP= 0.01;
00011     
00012     percentOfScale= ((1.0 - LP) * percentOfScale) + (LP * adc.read());
00013     resistance= (percentOfScale * R) / (1.0 - percentOfScale);
00014 }
00015 
00016 float TemperatureSensor::getKelvin(void) {
00017     float x;
00018 
00019     // Compute the Steinhard-Hart eqn:  1/t = A + B*ln(r) + C*ln(r)^3 + D*ln(r)^5
00020     static const float A= 1.006389097E-3;
00021     static const float B= 2.425678347E-4;
00022     static const float C= 1.452612422E-7;
00023 
00024     x= log(resistance);
00025     return 1.0 / (A + (B * x) + (C * x * x * x));
00026 }
00027 
00028 float TemperatureSensor::getResistance(void) {
00029     return resistance;
00030 }
00031 
00032 float TemperatureSensor::getPercentOfScale(void) {
00033     return percentOfScale;
00034 }