mirror of
https://github.com/RobTillaart/Arduino.git
synced 2024-09-20 08:55:59 -04:00
147 lines
4.0 KiB
C++
147 lines
4.0 KiB
C++
#pragma once
|
|
//
|
|
// FILE: MAX31855.h
|
|
// AUTHOR: Rob Tillaart
|
|
// VERSION: 0.4.1
|
|
// PURPOSE: Arduino library for MAX31855 chip for K type thermocouple
|
|
// DATE: 2014-01-01
|
|
// URL: https://github.com/RobTillaart/MAX31855_RT
|
|
// http://forum.arduino.cc/index.php?topic=208061
|
|
|
|
|
|
// Breakout board
|
|
//
|
|
// +---------+
|
|
// Vin | o |
|
|
// 3V3 | o |
|
|
// GND | o O | Thermocouple
|
|
// D0 | o O | Thermocouple
|
|
// CS | o |
|
|
// CLK | o |
|
|
// +---------+
|
|
|
|
|
|
#include "Arduino.h"
|
|
#include "SPI.h"
|
|
|
|
|
|
#define MAX31855_VERSION (F("0.4.1"))
|
|
|
|
#define MAX31855_NO_TEMPERATURE -999
|
|
|
|
// STATE constants returned by read()
|
|
#define STATUS_OK 0x00
|
|
#define STATUS_OPEN_CIRCUIT 0x01
|
|
#define STATUS_SHORT_TO_GND 0x02
|
|
#define STATUS_SHORT_TO_VCC 0x04
|
|
#define STATUS_ERROR 0x07
|
|
#define STATUS_NOREAD 0x80
|
|
#define STATUS_NO_COMMUNICATION 0x81
|
|
|
|
|
|
// Thermocouples working is based upon Seebeck effect.
|
|
// Different TC have a different Seebeck Coefficient (µV/°C)
|
|
// See http://www.analog.com/library/analogDialogue/archives/44-10/thermocouple.html
|
|
//
|
|
// As the MAX31855 is designed for K type sensors, one can calculate
|
|
// the factor needed to convert other sensors measurements.
|
|
// NOTE: this is only a linear approximation.
|
|
//
|
|
// Seebeck Coefficients (sensitivity) from the MAX31855 datasheet page 8
|
|
// to be used in setSeebeckCoefficient()
|
|
//
|
|
// TYPE COEFFICIENT
|
|
#define E_TC 76.373
|
|
#define J_TC 57.953
|
|
#define K_TC 41.276
|
|
#define N_TC 36.256
|
|
#define R_TC 10.506
|
|
#define S_TC 9.587
|
|
#define T_TC 52.18
|
|
|
|
|
|
class MAX31855
|
|
{
|
|
public:
|
|
|
|
MAX31855();
|
|
|
|
// HW SPI
|
|
void begin(uint8_t select);
|
|
// SW SPI
|
|
void begin(uint8_t clock, uint8_t select, uint8_t miso);
|
|
|
|
// returns state - bit field: 0 = STATUS_OK
|
|
uint8_t read();
|
|
|
|
float getInternal(void) const { return _internal; }
|
|
float getTemperature(void);
|
|
|
|
uint8_t getStatus(void) const { return _status; };
|
|
inline bool openCircuit() { return _status == STATUS_OPEN_CIRCUIT; };
|
|
inline bool shortToGND() { return _status == STATUS_SHORT_TO_GND; };
|
|
inline bool shortToVCC() { return _status == STATUS_SHORT_TO_VCC; };
|
|
inline bool genericError() { return _status == STATUS_ERROR; };
|
|
inline bool noRead() { return _status == STATUS_NOREAD; };
|
|
inline bool noCommunication() { return _status == STATUS_NO_COMMUNICATION; };
|
|
|
|
// use offset to calibrate the TC.
|
|
void setOffset(const float t) { _offset = t; };
|
|
float getOffset() const { return _offset; };
|
|
|
|
// set the above E_TC or other Seebeck Coefficients
|
|
// one can also set your own optimized values.
|
|
void setSeebeckCoefficient(const float SC) { _SeebeckC = SC; };
|
|
float getSeebeckCoefficient() const { return _SeebeckC; };
|
|
|
|
uint32_t lastRead() { return _lastTimeRead; };
|
|
uint32_t getRawData() { return _rawData;};
|
|
|
|
// speed in Hz
|
|
void setSPIspeed(uint32_t speed);
|
|
uint32_t getSPIspeed() { return _SPIspeed; };
|
|
void setSWSPIdelay(uint16_t del = 0) { _swSPIdelay = del; };
|
|
uint16_t getSWSPIdelay() { return _swSPIdelay; };
|
|
|
|
|
|
|
|
// ESP32 specific
|
|
#if defined(ESP32)
|
|
void selectHSPI() { _useHSPI = true; };
|
|
void selectVSPI() { _useHSPI = false; };
|
|
bool usesHSPI() { return _useHSPI; };
|
|
bool usesVSPI() { return !_useHSPI; };
|
|
|
|
// to overrule ESP32 default hardware pins
|
|
void setGPIOpins(uint8_t clock, uint8_t miso, uint8_t mosi, uint8_t select);
|
|
#endif
|
|
|
|
|
|
private:
|
|
uint32_t _read();
|
|
|
|
uint8_t _status;
|
|
float _internal;
|
|
float _temperature;
|
|
float _offset;
|
|
float _SeebeckC;
|
|
uint32_t _lastTimeRead;
|
|
uint32_t _rawData;
|
|
bool _hwSPI;
|
|
|
|
uint8_t _clock;
|
|
uint8_t _miso;
|
|
uint8_t _select;
|
|
|
|
uint16_t _swSPIdelay = 0;
|
|
uint32_t _SPIspeed;
|
|
SPIClass * mySPI;
|
|
SPISettings _spi_settings;
|
|
#if defined(ESP32)
|
|
bool _useHSPI = true;
|
|
#endif
|
|
};
|
|
|
|
|
|
// -- END OF FILE --
|