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89 lines
2.3 KiB
C++
89 lines
2.3 KiB
C++
//
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// FILE: MAX31855.h
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// AUTHOR: Rob Tillaart
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// VERSION: 0.1.08
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// PURPOSE: MAX31855 - Thermocouple
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// DATE: 2014-01-01
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// URL: http://forum.arduino.cc/index.php?topic=208061
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//
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// Released to the public domain
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//
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#ifndef MAX31855_H
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#define MAX31855_H
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#if (ARDUINO < 100)
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#include "WProgram.h"
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#else
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#include "Arduino.h"
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#endif
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#define MAX31855_VERSION "0.1.08"
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#define STATUS_OK 0x00
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#define STATUS_OPEN_CIRCUIT 0x01
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#define STATUS_SHORT_TO_GND 0x02
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#define STATUS_SHORT_TO_VCC 0x04
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#define STATUS_NOREAD 0x80
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// Thermocouples working is based upon Seebeck effect.
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// Different TC have a different Seebeck Coefficient (µV/°C)
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// From http://www.analog.com/library/analogDialogue/archives/44-10/thermocouple.html
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//
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// As the MAX31855 is designed for K type sensors, one can calculate
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// the factor needed to convert other sensors measurements.
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// note this is only a linear approximation.
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//
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// E_TC = 61 => 41/61 = 0.6721311475
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// J_TC = 52 => 41/52 = 0.7884615385
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// K_TC = 41 => 41/41 = 1
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// N_TC = 27 => 41/27 = 1.5185185185
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// R_TC = 9 => 41/9 = 4.5555555556
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// S_TC = 6 => 41/6 = 6.8333333333
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// T_TC = 41 => 41/41 = 1
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// 0.1.07 updated with numbers from the MAX31855 datasheet
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#define E_TC (41.276/76.373)
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#define J_TC (41.276/57.953)
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#define K_TC (41.276/41.276)
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#define N_TC (41.276/36.256)
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#define R_TC (41.276/10.506)
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#define S_TC (41.276/9.587)
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#define T_TC (41.276/52.18)
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class MAX31855
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{
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public:
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MAX31855(uint8_t SCLK, uint8_t CS, uint8_t MISO);
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void begin();
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uint8_t read();
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double getInternal(void) const { return _internal; };
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double getTemperature(void) const { return _temperature * _TCfactor; }
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uint8_t getStatus(void) const { return _status; };
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void setOffset(const double t) { _offset = t; };
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double getOffset() const { return _offset; };
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void setTCfactor(const double TCfactor) { _TCfactor = TCfactor; };
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double getTCfactor() const { return _TCfactor; };
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private:
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uint32_t _read();
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double _internal;
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double _temperature;
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uint8_t _status;
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double _offset;
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double _TCfactor;
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uint8_t _sclk;
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uint8_t _miso;
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uint8_t _cs;
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};
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#endif
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// END OF FILE
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