Maxim Integrated
Library for the MAX31856 Precision Thermocouple to Digital Converter with Linearization
Dependents: MAX31856_example_program
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MAX31856.h
- Committer:
- DevinAlexander
- Date:
- 2017-09-14
- Revision:
- 1:a1bbb5c254f2
- Parent:
- 0:b714c6a7c969
File content as of revision 1:a1bbb5c254f2:
/******************************************************************//**
* @file MAX31856.h
*
* @author Devin Alexander
*
* @version 1.0
*
* Started: SEPTEMBER 14th 2017
*
* Updated:
*
* @brief Header file for MAX31856 class
*
***********************************************************************
*
* @copyright
* Copyright (C) 2017 Maxim Integrated Products, Inc., All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL MAXIM INTEGRATED BE LIABLE FOR ANY CLAIM, DAMAGES
* OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*
* Except as contained in this notice, the name of Maxim Integrated
* Products, Inc. shall not be used except as stated in the Maxim Integrated
* Products, Inc. Branding Policy.
*
* The mere transfer of this software does not imply any licenses
* of trade secrets, proprietary technology, copyrights, patents,
* trademarks, maskwork rights, or any other form of intellectual
* property whatsoever. Maxim Integrated Products, Inc. retains all
* ownership rights.
**********************************************************************/
#ifndef MAX31856_h
#define MAX31856_h
#include "mbed.h"
//*****************************************************************************
//Define all the addresses of the registers in the MAX31856
//*****************************************************************************
#define ADDRESS_CR0_READ 0x00 //Factory Default 00h
#define ADDRESS_CR0_WRITE 0x80
#define ADDRESS_CR1_READ 0x01 //Factory Default 03h
#define ADDRESS_CR1_WRITE 0x81
#define ADDRESS_MASK_READ 0x02 //Factory Default FFh
#define ADDRESS_MASK_WRITE 0x82
#define ADDRESS_CJHF_READ 0x03 //Factory Default 7Fh
#define ADDRESS_CJHF_WRITE 0x83
#define ADDRESS_CJLF_READ 0x04 //Factory Default C0h
#define ADDRESS_CJLF_WRITE 0x84
#define ADDRESS_LTHFTH_READ 0x05 //Factory Default 7Fh
#define ADDRESS_LTHFTH_WRITE 0x85
#define ADDRESS_LTHFTL_READ 0x06 //Factory Default FFh
#define ADDRESS_LTHFTL_WRITE 0x86
#define ADDRESS_LTLFTH_READ 0x07 //Factory Default 80h
#define ADDRESS_LTLFTH_WRITE 0x87
#define ADDRESS_LTLFTL_READ 0x08 //Factory Default 00h
#define ADDRESS_LTLFTL_WRITE 0x88
#define ADDRESS_CJTO_READ 0x09 //Factory Default 00h
#define ADDRESS_CJTO_WRITE 0x89
#define ADDRESS_CJTH_READ 0x0A //Factory Default 00h
#define ADDRESS_CJTH_WRITE 0x8A
#define ADDRESS_CJTL_READ 0x0B //Factory Default 00h
#define ADDRESS_CJTL_WRITE 0x8B
#define ADDRESS_LTCBH_READ 0x0C
#define ADDRESS_LTCBM_READ 0x0D
#define ADDRESS_LTCBL_READ 0x0E
#define ADDRESS_SR_READ 0x0F
//*****************************************************************************
//Define parameters for control register zero (CR0)
//*****************************************************************************
#define CR0_CONV_MODE_NORMALLY_OFF 0x00 //Power On Default value
#define CR0_CONV_MODE_NORMALLY_ON 0x80
#define CR0_1_SHOT_MODE_NO_CONVERSION 0x00 //defaults to this value
#define CR0_1_SHOT_MODE_ONE_CONVERSION 0x40 //^
#define CR0_OC_DETECT_DISABLED 0x00
#define CR0_OC_DETECT_ENABLED_R_LESS_5k 0x10
#define CR0_OC_DETECT_ENABLED_TC_LESS_2ms 0x20
#define CR0_OC_DETECT_ENABLED_TC_MORE_2ms 0x30
#define CR0_COLD_JUNC_ENABLE 0x00 //Power On Default value
#define CR0_COLD_JUNC_DISABLE 0x08 //speed of conversion is sped up by 25ms when this optionis selected (Disable the cold junc)
#define CR0_FAULT_MODE_COMPARATOR 0x00 //Power On Default value
#define CR0_FAULT_MODE_INTERUPT 0x04
#define CR0_FAULTCLR_DEFAULT_VAL 0x00 //defaults to this value
#define CR0_FAULTCLR_RETURN_FAULTS_TO_ZERO 0x02 //^
#define CR0_FILTER_OUT_60Hz 0x00 //Preset value
#define CR0_FILTER_OUT_50Hz 0x01 //^
//*****************************************************************************
//Define parameters for control register one (CR1)
//*****************************************************************************
#define CR1_AVG_TC_SAMPLES_1 0x00 //Power on default value
#define CR1_AVG_TC_SAMPLES_2 0x10
#define CR1_AVG_TC_SAMPLES_4 0x20
#define CR1_AVG_TC_SAMPLES_8 0x30
#define CR1_AVG_TC_SAMPLES_16 0x40
// Define which type of thermocouple the MAX31856 is using. This is for lineariztion purposes
#define CR1_TC_TYPE_B 0x00
#define CR1_TC_TYPE_E 0x01
#define CR1_TC_TYPE_J 0x02
#define CR1_TC_TYPE_K 0x03 //Power on default value
#define CR1_TC_TYPE_N 0x04
#define CR1_TC_TYPE_R 0x05
#define CR1_TC_TYPE_S 0x06
#define CR1_TC_TYPE_T 0x07
#define CR1_TC_TYPE_VOLT_MODE_GAIN_8 0x08
#define CR1_TC_TYPE_VOLT_MODE_GAIN_32 0x0C
//*****************************************************************************
//Define parameters for the mask register (MASK)
//*****************************************************************************
#define MASK_CJ_FAULT_THRESHOLD_HIGH 0x20
#define MASK_CJ_FAULT_THRESHOLD_LOW 0x10
#define MASK_TC_FAULT_THRESHOLD_HIGH 0x08
#define MASK_TC_FAULT_THRESHOLD_LOW 0x04
#define MASK_OVER_UNDER_VOLT_FAULT 0x02
#define MASK_OPEN_CIRCUIT_FAULT 0x01
//*****************************************************************************
//If these defined values are &= (bitwise ANDed) with the contents of a register, it will reset the bits pertaing to the specific bitfields to zero
//*****************************************************************************
#define CR0_CLEAR_BITS_7 ~(0x80)
#define CR0_CLEAR_BITS_6 ~(0x40)
#define CR0_CLEAR_BITS_5_4 ~(0x30)
#define CR0_CLEAR_BITS_3 ~(0x08)
#define CR0_CLEAR_BITS_2 ~(0x04)
#define CR0_CLEAR_BITS_1 ~(0x02)
#define CR0_CLEAR_BITS_0 ~(0x01)
#define CR1_CLEAR_BITS_6_4 ~(0x70)
#define CR1_CLEAR_BITS_3_0 ~(0x0F)
#define MASK_CLEAR_BITS_5 ~(0x20)
#define MASK_CLEAR_BITS_4 ~(0x10)
#define MASK_CLEAR_BITS_3 ~(0x08)
#define MASK_CLEAR_BITS_2 ~(0x04)
#define MASK_CLEAR_BITS_1 ~(0x02)
#define MASK_CLEAR_BITS_0 ~(0x01)
//*****************************************************************************
///Parameters that are used throughout the library
//*****************************************************************************
#define TC_MAX_VAL_FAULT 1800
#define TC_MIN_VAL_FAULT -210
#define CJ_MAX_VAL_FAULT 125
#define CJ_MIN_VAL_FAULT -55
/**
* @brief Library for the MAX31856\n
* The MAX31856 thermocouple temperature sensor accurately measures temperature
* and provides a vast amount of features such as:
* //FEATURE
* //FEATURE
* //FEATURE
* //FEATURE
* //FEATURE
* //FEATURE
* Communication is through an SPI-compatible interface.
*
* @code
* #include "mbed.h"
* #include "MAX31856.h"
*
*
* // Hardware serial port
* Serial serial(USBTX, USBRX);
*
* //SPI communications
* SPI spi(SPIO MOSI,SPIO MISO,SPIO SCK);
*
* //Thermocouples
* MAX31856 Thermocouple1(spi, CHIPSELECT);
*
*
* int main(void)
* {
* float temperature_TC_1, temperature_CJ_1;
* while(true)
* {
* temperature_TC_1=Thermocouple1.readTC();
* temperature_CJ_1=Thermocouple1.readCJ();
* serial.printf("MAX31856 TC = %f Celsius MAX31856 CJ = %f Celsius \n\r",temperature_TC_1,temperature_CJ_1);
* wait(1.0);
* }
* }
* @endcode
*/
/** Please see pages 18-26 in the MAX31856 data sheet to see what register bit masks are needed to be set
to achieve functionality desired. The data sheet can be found at
*** https://datasheets.maximintegrated.com/en/ds/MAX31856.pdf ***
*/
/**
* MAX31856 Class
*/
class MAX31856
{
public:
//*****************************************************************************
//Constructor and Destructor for the class
//*****************************************************************************
/**
* @brief Constructor to create MAX31856 object with SPI information as well as preconfiguration parameter settings in configuration registers Zero and One
* @param _spi - Reference to SPI object
* @param _ncs - Chip Select for SPI comunications with the oject
* @param _type - Type of thermocouple used
* @param _fltr - Feature of the MAX31856 to filter out either 50Hz/60Hz from signal
* @param _samples - How many samples are averaged for one conversion
* @param _conversion_mode - Choose between always on and making conversions and off in between requests for a reading
*/
MAX31856(SPI& _spi, PinName _ncs, uint8_t _type=CR1_TC_TYPE_K, uint8_t _fltr=CR0_FILTER_OUT_60Hz, uint8_t _samples=CR1_AVG_TC_SAMPLES_1, uint8_t _conversion_mode=CR0_CONV_MODE_NORMALLY_OFF);
/** @brief Destructor */
~MAX31856(void);
//*****************************************************************************
//Temperature Functions
//*****************************************************************************
/**
* @brief Requests read of the thermocouple temperature
* @return float of the converted thermocouple reading based on current configurations
*/
float readTC();
/**
* @brief Requests read of the cold junction temperature
* @return float of the converted artificial cold junction reading based on current configurations
*/
float readCJ();
//*****************************************************************************
//Functions for register CR0
//*****************************************************************************
/**
* @brief Sets bits in the configuration register zero for setting the rate of conversions
* @param val \li CR0_CONV_MODE_NORMALLY_OFF (Power On Default value)
* \li CR0_CONV_MODE_NORMALLY_ON
* @return \li 1 on success
* \li 0 if there is an incorrect parameter that is passed in as parameter val
*/
bool setConversionMode(uint8_t val);
/**
* @brief Sets bits in the configuration register zero for enabling one conversion to take place
* @param val \li CR0_1_SHOT_MODE_NO_CONVERSION (Power On Default value)
* \li CR0_1_SHOT_MODE_ONE_CONVERSION (This bit self clears itself to default back to CR0_1_SHOT_MODE_NO_CONVERSION after singular conversion takes place)
* @return \li 1 on success
* \li 0 if there is an incorrect parameter that is passed in as parameter val
*/
bool setOneShotMode(uint8_t val);
/**
* @brief Sets bits in the configuration register zero for configuring open circuit fault detection
* @param val \li CR0_OC_DETECT_DISABLED (Power On Default value)
* \li CR0_OC_DETECT_ENABLED_R_LESS_5k
* \li CR0_OC_DETECT_ENABLED_TC_LESS_2ms
* \li CR0_OC_DETECT_ENABLED_TC_MORE_2ms
* @return \li 1 on success
* \li 0 if there is an incorrect parameter that is passed in as parameter val
*/
bool setOpenCircuitFaultDetection(uint8_t val);
/**
* @brief Sets bits in the configuration register zero for disabling or enabling the Cold Junction
* @param val \li CR0_COLD_JUNC_ENABLE (Power On Default value)
* \li CR0_COLD_JUNC_DISABLE
* @return \li 1 on success
* \li 0 if there is an incorrect parameter that is passed in as parameter val
*/
bool setColdJunctionDisable(uint8_t val);
/**
* @brief Sets bits in the configuration register zero for setting fault mode status
* @param val \li CR0_FAULT_MODE_COMPARATOR (Power On Default value)
* \li CR0_FAULT_MODE_INTERUPT
* @return \li 1 on success
* \li 0 if there is an incorrect parameter that is passed in as parameter val
*/
bool setFaultMode(uint8_t val);
/**
* @brief Sets bits in the configuration register zero for clearing fault status
* @param val \li CR0_FAULTCLR_DEFAULT_VAL (Power On Default value)
* \li CR0_FAULTCLR_RETURN_FAULTS_TO_ZERO (This bit self clears itself to default back to CR0_FAULTCLR_DEFAULT_VAL after fault status is cleared)
* @return \li 1 on success
* \li 0 if there is an incorrect parameter that is passed in as parameter val
*/
bool setFaultStatusClear(uint8_t val);
/**
* @brief Sets bits in the configuration register zero for setting which of the two filter modes either 50Hz or 60Hz cancelation
* @param val \li CR0_FILTER_OUT_60Hz (Power On Default value)
* \li CR0_FILTER_OUT_50Hz
* @return \li 1 on success
* \li 0 if there is an incorrect parameter that is passed in as parameter val
*/
bool setEmiFilterFreq(uint8_t val);
//*****************************************************************************
//Functions for register CR1
//*****************************************************************************
/**
* @brief Sets bits in the configuration register one for setting how many readings are taken
* @param val \li CR1_AVG_TC_SAMPLES_1 (Power On Default value)
* \li CR1_AVG_TC_SAMPLES_2
* \li CR1_AVG_TC_SAMPLES_4
* \li CR1_AVG_TC_SAMPLES_8
* \li CR1_AVG_TC_SAMPLES_16
* @return \li 1 on success
* \li 0 if there is an incorrect parameter that is passed in as parameter val
*/
bool setNumSamplesAvg(uint8_t val);
/**
* @brief Sets bits in the configuration register one for setting which thermocouple type is going to be programmed into the MAX31856 for linearization of thermovoltage produced and temperature
* @param val \li CR1_TC_TYPE_B
* \li CR1_TC_TYPE_E
* \li CR1_TC_TYPE_J
* \li CR1_TC_TYPE_K (Power On Default value)
* \li CR1_TC_TYPE_N
* \li CR1_TC_TYPE_R
* \li CR1_TC_TYPE_S
* \li CR1_TC_TYPE_T
* \li CR1_TC_TYPE_VOLT_MODE_GAIN_8
* \li CR1_TC_TYPE_VOLT_MODE_GAIN_32
* @return \li 1 on success
* \li 0 if there is an incorrect parameter that is passed in as parameter val
*/
bool setThermocoupleType(uint8_t val);
//*****************************************************************************
//Functions for register MASK
//*****************************************************************************
/**
* @brief Sets bits in the configuration register one for setting fault masks
* @param val \li MASK_CJ_FAULT_THRESHOLD_HIGH
* \li MASK_CJ_FAULT_THRESHOLD_LOW
* \li MASK_TC_FAULT_THRESHOLD_HIGH
* \li MASK_TC_FAULT_THRESHOLD_LOW
* \li MASK_OVER_UNDER_VOLT_FAULT
* \li MASK_OPEN_CIRCUIT_FAULT
* @param enable \li 0 for disabling the mask in whichever option is selcted in parameter val
* \li 1 for enabling the mask in whichever option is selcted in parameter val
* @return \li 1 on success
* \li 0 if there is an incorrect parameter that is passed in as parameter val
*/
bool setFaultMasks(uint8_t val, bool enable);
/**
* @brief Sets bits in the configuration register one for setting thresholds that corespond to the fault mask settings
* @param val \li MASK_CJ_FAULT_THRESHOLD_HIGH
* \li MASK_CJ_FAULT_THRESHOLD_LOW
* \li MASK_TC_FAULT_THRESHOLD_HIGH
* \li MASK_TC_FAULT_THRESHOLD_LOW
* @param temperature value that you want to program into a threshold register for temperatre
* @return return value that was programmed into the threshold register
*/
bool setFaultThresholds(uint8_t val, float temperature);
//*****************************************************************************
//Check Fault Status Functions
//*****************************************************************************
/**
* @brief Check the fault stautus register to see if there is anything wrong with range of thermocouple temperature
* whether outside opperating temperatures or if above/below thresholds that are set
* @return \li 0 if no faults are present
* \li 1 if Thermocouple temp is higher than the threshold
* \li 2 if Thermocouple temp is lower than the threshold
* \li 3 if Thermocouple temp is outside operating range of termocouple type
* \li 4 if Thermocouple temp is higher than the threshold && is outside operating range of termocouple type
* \li 5 if Thermocouple temp is lower than the threshold && is outside operating range of termocouple type
*/
uint8_t checkFaultsThermocoupleThresholds();
/**
* @brief Check the fault stautus register to see if there is anything wrong with range of cold junction temperature
* whether outside opperating temperatures or if above/below thresholds that are set
* @return \li 0 if no faults are present
* \li 1 if Cold Junction temp is higher than the threshold
* \li 2 if Cold Junction temp is lower than the threshold
* \li 3 if Cold Junction temp is outside operating range of termocouple type
* \li 4 if Cold Junction temp is higher than the threshold && is outside operating range of termocouple type
* \li 5 if Cold Junction temp is lower than the threshold && is outside operating range of termocouple type
*/
uint8_t checkFaultsColdJunctionThresholds();
/**
* @brief Check the fault stautus register to see if there is anything wrong with thermocouple connection to the MAX31856
* @return \li 1 if no faults are present
* \li 0 if there is a fault and there needs to be information printed to the console to help diagnose issues
*/
bool checkFaultsThermocoupleConnection();
//*****************************************************************************
//General Functions
//*****************************************************************************
/**
* @brief This function is to read current contents of register, manipulate the contents, then rewrite the specific register\n
* \li Read the value of a register from contents of register matching the parameter read_address
* \li Clear the bits needed to be changed by bitwise ANDing the read value with the 8 bit parameter clear_bits
* \li Set the bits of interest in the 8 bit value by bitwise ORing the value from step two with parameter val
* \li Rewrite to the register with the new 8 bit value to the register with the address with parameter write_address
* @param read_address - Address of register to read the data before it's changed
* @param write_address - Address of register to rewrite the changed data
* @param clear_bits - Parameter that is
* @param val - Bitfield that contains bits related to function specific settings
* @return \li 1 on success
*/
bool registerReadWriteByte(uint8_t read_address, uint8_t write_address, int clear_bits, uint8_t val);
/**
* @brief This function is to read current contents of register, manipulate the contents, then rewrite the specific register\n
* \li Read the value of a register from contents of register matching the parameter read_address
* \li Clear the bits needed to be changed by bitwise ANDing the read value with the 8 bit parameter clear_bits
* \li Set the bits of interest in the 8 bit value by bitwise ORing the value from step two with parameter val
* \li Write to the register with the new 8 bit value to the register with the address with parameter write_address
* @param write_address - Address of register to rewrite the changed data
* @param val - Byte of information that is going to be written to the regitser with the address that matches the parameter write_address
* @return \li 1 on success
*/
bool registerWriteByte(uint8_t write_address, uint8_t val);
/**
* @brief This function is to read current contents of register by passing in the address of the read address and return contents of the register
* @param read_address - Address of register to read data from
* @return \li byte contained in the address
*/
uint8_t registerReadByte(uint8_t read_address);
/**
* @brief This function is to read current contents of register by passing in the address of the read address and return contents of the register
* @param temperature - Float of value to offest the value of the cold junction offset by (must be between -8°C to +7.9375°C)
* @return \li 1 on successfully updated coldjunction offset
* \li 0 if parameter temperature does not fall between range -8°C to +7.9375°C
*/
bool coldJunctionOffset(float temperature);
private:
//*****************************************************************************
//Private Functions
//*****************************************************************************
/** @brief Writes the chip seleect pin low to begin SPI communications */
void spiEnable();
/** @brief Writes the chip seleect pin high to end SPI communications */
void spiDisable();
/** @brief Calculates minimum wait time for a conversion to take place */
void calculateDelayTime();
//*****************************************************************************
//Private Members
//*****************************************************************************
/// SPI object
SPI& spi;
/// Chip select pin for SPI communications
DigitalOut ncs;
/// Number of samples the thermocouple is configured to average
uint8_t samples;
/// 0=thermocouple is set to one of 8 thermocouple types and 1=Thermocouple is configured to report in voltage mode
bool voltage_mode;
/// 0=60Hz and 1=50Hz
bool filter_mode;
/// 0=MAX31856 is off, so no conversion is taking place currently and 1=Always On and converting
bool conversion_mode;
/// 0=cold junction is disabled and 1=cold junction is enabled
bool cold_junction_enabled;
///Define a return val for all boolean functions
bool return_val;
///Used to figure out when a new conversion is ready to go
uint32_t lastReadTime;
///How many conversions have taken place since conversion mode was switched into auto mode
///Also this value should be 0 if the mode is in oneshot mode
uint32_t thermocouple_conversion_count;
///time in milliseconds that is needed minimum for a new conversion to take place
uint32_t conversion_time;
};
#endif /* __MAX31856_H_ */