Maxim Integrated
Library for the MAX31856 Precision Thermocouple to Digital Converter with Linearization
Dependents: MAX31856_example_program
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MAX31856
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Diff: MAX31856.h
- Revision:
- 0:b714c6a7c969
- Child:
- 1:a1bbb5c254f2
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+++ b/MAX31856.h Thu Sep 14 17:56:47 2017 +0000
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+/*******************************************************************************
+ * 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_ */