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44 lines
1.3 KiB
44 lines
1.3 KiB
4 years ago
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#include "temperature_sensor.h"
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TemperatureSensor::TemperatureSensor(byte pin, int refResistance, double a, double b, double c) {
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this->pin = pin;
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this->refResistance = refResistance;
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this->a = a;
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this->b = b;
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this->c = c;
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init();
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}
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#define DEBUG_OUTPUT Serial
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void TemperatureSensor::init() {
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pinMode(pin, INPUT);
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}
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void TemperatureSensor::preload() {
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for(int i=0; i< 10; i++){
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update();
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}
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}
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void TemperatureSensor::update() {
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if(measurementCounter < 10){ //Measure 10 times before calculating temperature from average
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measurementAccumulative += analogRead(pin);
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measurementCounter++;
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} else {
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int sensorValue = measurementAccumulative/measurementCounter;
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// voltage = sensorValue*5.0/1024.0
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// r1 = (vdd-vout)*r2/vout
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double resistance = ((1.0-sensorValue/1024.0)*refResistance/(sensorValue/1024.0)); // this is our probe resistance.
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double lt = log(resistance);
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temperature = (1 / (a+b*lt+c*lt*lt*lt)) - 273.15; //Calculate temperature in Kelvin according to Steinhart-Hart equation, then convert to Celcius
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if(temperature < -35) temperature = sqrt (-1); // If value is unpossibly low, return NaN
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measurementAccumulative = 0;
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measurementCounter = 0;
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}
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}
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float TemperatureSensor::getTemperature() {
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return temperature;
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}
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