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/*
* Thermistor.h
*
* Created on: 10 Nov 2016
* Author: David
*/
#ifndef SRC_HEATING_THERMISTOR_H_
#define SRC_HEATING_THERMISTOR_H_
#include "SensorWithPort.h"
// The Steinhart-Hart equation for thermistor resistance is:
// 1/T = A + B ln(R) + C [ln(R)]^3
//
// The simplified (beta) equation assumes C=0 and is:
// 1/T = A + (1/Beta) ln(R)
//
// The parameters that can be configured in RRF are R25 (the resistance at 25C), Beta, and optionally C.
class Thermistor : public SensorWithPort
{
public:
Thermistor(unsigned int sensorNum, bool p_isPT1000); // create an instance with default values
GCodeResult Configure(GCodeBuffer& gb, const StringRef& reply) override; // configure the sensor from M305 parameters
static constexpr const char *TypeNameThermistor = "thermistor";
static constexpr const char *TypeNamePT1000 = "pt1000";
void Poll() override;
private:
// For the theory behind ADC oversampling, see http://www.atmel.com/Images/doc8003.pdf
static constexpr unsigned int AdcOversampleBits = 2; // we use 2-bit oversampling
void CalcDerivedParameters(); // calculate shA and shB
// The following are configurable parameters
float r25, beta, shC, seriesR; // parameters declared in the M305 command
int8_t adcFilterChannel;
bool isPT1000; // true if it is a PT1000 sensor, not a thermistor
// Duet 3 VRef calibration doesn't work well on the MB6HC v0.6 or v1.0 so provide calibration adjustment
#if !HAS_VREF_MONITOR || defined(DUET3)
int16_t adcLowOffset, adcHighOffset;
#endif
// The following are derived from the configurable parameters
float shA, shB; // derived parameters
static constexpr int32_t OversampledAdcRange = 1u << (AdcBits + AdcOversampleBits); // The readings we pass in should be in range 0..(AdcRange - 1)
};
#endif /* SRC_HEATING_THERMISTOR_H_ */
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