Analog Devices / Mbed OS EVAL-AD7124-Temperature_measurement

Important changes to repositories hosted on mbed.com

Mbed hosted mercurial repositories are deprecated and are due to be permanently deleted in July 2026.

To keep a copy of this software download the repository Zip archive or clone locally using Mercurial.

It is also possible to export all your personal repositories from the account settings page.

Dependencies:   tempsensors adi_console_menu platform_drivers

app/ad7124_temperature_sensor.cpp@3:f20f09251190, 2021-03-19 (annotated)

Committer:
mahphalke
Date:
Fri Mar 19 14:34:05 2021 +0530
Revision:
3:f20f09251190
Parent:
1:c863d7e9e272 
Updates w.r.t temperature measurement display schemes

Who changed what in which revision?

UserRevisionLine numberNew contents of line
mahphalke 1:c863d7e9e272 1
mahphalke 1:c863d7e9e272 2 /***************************************************************************//*
mahphalke 1:c863d7e9e272 3 * @file ad7124_temperature_sensor.cpp
mahphalke 1:c863d7e9e272 4 * @brief AD7124 temperature sensor functionality
mahphalke 1:c863d7e9e272 5 * @details
mahphalke 1:c863d7e9e272 6 ******************************************************************************
mahphalke 1:c863d7e9e272 7 * Copyright (c) 2021 Analog Devices, Inc. All Rights Reserved.
mahphalke 1:c863d7e9e272 8 *
mahphalke 1:c863d7e9e272 9 * This software is proprietary to Analog Devices, Inc. and its licensors.
mahphalke 1:c863d7e9e272 10 * By using this software you agree to the terms of the associated
mahphalke 1:c863d7e9e272 11 * Analog Devices Software License Agreement.
mahphalke 1:c863d7e9e272 12 ******************************************************************************/
mahphalke 1:c863d7e9e272 13
mahphalke 1:c863d7e9e272 14 /******************************************************************************/
mahphalke 1:c863d7e9e272 15 /***************************** Include Files **********************************/
mahphalke 1:c863d7e9e272 16 /******************************************************************************/
mahphalke 1:c863d7e9e272 17
mahphalke 1:c863d7e9e272 18 #include <stdint.h>
mahphalke 1:c863d7e9e272 19 #include <math.h>
mahphalke 1:c863d7e9e272 20
mahphalke 1:c863d7e9e272 21 #include <thermocouple.h>
mahphalke 1:c863d7e9e272 22 #include <ptxxx.h>
mahphalke 1:c863d7e9e272 23 #include <ntc_10k_44031.h>
mahphalke 1:c863d7e9e272 24 #include <ptc_ky81_110.h>
mahphalke 1:c863d7e9e272 25
mahphalke 1:c863d7e9e272 26 #include "ad7124_temperature_sensor.h"
mahphalke 1:c863d7e9e272 27
mahphalke 1:c863d7e9e272 28 #ifdef __cplusplus
mahphalke 1:c863d7e9e272 29 extern "C"
mahphalke 1:c863d7e9e272 30 {
mahphalke 1:c863d7e9e272 31 #endif // _cplusplus
mahphalke 1:c863d7e9e272 32
mahphalke 1:c863d7e9e272 33 #include "ad7124_regs_configs.h"
mahphalke 1:c863d7e9e272 34 #include "ad7124_support.h"
mahphalke 1:c863d7e9e272 35
mahphalke 1:c863d7e9e272 36 #ifdef __cplusplus // Closing extern c
mahphalke 1:c863d7e9e272 37 }
mahphalke 1:c863d7e9e272 38 #endif // _cplusplus
mahphalke 1:c863d7e9e272 39
mahphalke 1:c863d7e9e272 40 /******************************************************************************/
mahphalke 1:c863d7e9e272 41 /********************* Macros and Constants Definitions ***********************/
mahphalke 1:c863d7e9e272 42 /******************************************************************************/
mahphalke 1:c863d7e9e272 43
mahphalke 1:c863d7e9e272 44 /* NTC thermistor Rsense value (in ohms) */
mahphalke 3:f20f09251190 45 #define NTC_RSENSE 10000U
mahphalke 3:f20f09251190 46
mahphalke 3:f20f09251190 47 /* RTD Rref Resistance value (in ohms) */
mahphalke 3:f20f09251190 48 #define RTD_RREF 5110U
mahphalke 1:c863d7e9e272 49
mahphalke 1:c863d7e9e272 50 /* PTC thermistor Ref Resistance value (in ohms) */
mahphalke 3:f20f09251190 51 #define PTC_RREF 5110U
mahphalke 1:c863d7e9e272 52
mahphalke 1:c863d7e9e272 53 /******************************************************************************/
mahphalke 1:c863d7e9e272 54 /******************** Variables and User Defined Data Types *******************/
mahphalke 1:c863d7e9e272 55 /******************************************************************************/
mahphalke 1:c863d7e9e272 56
mahphalke 1:c863d7e9e272 57 /* Calibration constant (iout ratio) for RTD resistance measurement */
mahphalke 1:c863d7e9e272 58 static float calibration_iout_ratio = 1;
mahphalke 1:c863d7e9e272 59
mahphalke 1:c863d7e9e272 60 /******************************************************************************/
mahphalke 1:c863d7e9e272 61 /************************** Functions Definitions *****************************/
mahphalke 1:c863d7e9e272 62 /******************************************************************************/
mahphalke 1:c863d7e9e272 63
mahphalke 1:c863d7e9e272 64 /*!
mahphalke 1:c863d7e9e272 65 * @brief Convert the ADC raw value into equivalent RTD resistance
mahphalke 1:c863d7e9e272 66 * @param adc_raw[in]- ADC raw sample
mahphalke 3:f20f09251190 67 * @param gain[in] - RTD gain
mahphalke 1:c863d7e9e272 68 * @return RTD resistance value
mahphalke 1:c863d7e9e272 69 * @note RTD is biased with constant excitation current. Below formula
mahphalke 1:c863d7e9e272 70 * is based on ratiometric measurement, where fixed value of RTD RREF
mahphalke 1:c863d7e9e272 71 * (reference resistor) and gain is taken into account
mahphalke 1:c863d7e9e272 72 */
mahphalke 3:f20f09251190 73 static float convert_adc_raw_into_rtd_resistance(int32_t adc_raw, uint8_t gain)
mahphalke 1:c863d7e9e272 74 {
mahphalke 1:c863d7e9e272 75 float rtd_res;
mahphalke 1:c863d7e9e272 76
mahphalke 1:c863d7e9e272 77 /* Below equation is for bipolar inputs as all ADC configurations for
mahphalke 1:c863d7e9e272 78 * sensor measurement are having default bipolar mode */
mahphalke 1:c863d7e9e272 79 rtd_res = (((float)adc_raw - (1 << (AD7124_ADC_N_BITS - 1))) *
mahphalke 1:c863d7e9e272 80 (calibration_iout_ratio * RTD_RREF)) / ((
mahphalke 3:f20f09251190 81 AD7124_PGA_GAIN(gain)) * (1 << (AD7124_ADC_N_BITS - 1)));
mahphalke 1:c863d7e9e272 82
mahphalke 1:c863d7e9e272 83 return rtd_res;
mahphalke 1:c863d7e9e272 84 }
mahphalke 1:c863d7e9e272 85
mahphalke 1:c863d7e9e272 86
mahphalke 1:c863d7e9e272 87 /*!
mahphalke 1:c863d7e9e272 88 * @brief Store the RTD calibration Iout ratio for 3-wire RTD calibration
mahphalke 1:c863d7e9e272 89 * based measurement
mahphalke 1:c863d7e9e272 90 * @param iout_ratio[in]- Iout1/Iout0 ratio
mahphalke 1:c863d7e9e272 91 * @param status[in] - Calibration ratio set/reset flag
mahphalke 1:c863d7e9e272 92 * @return none
mahphalke 1:c863d7e9e272 93 */
mahphalke 1:c863d7e9e272 94 void store_rtd_calibrated_iout_ratio(float iout_ratio, bool status)
mahphalke 1:c863d7e9e272 95 {
mahphalke 1:c863d7e9e272 96 if (status) {
mahphalke 1:c863d7e9e272 97 calibration_iout_ratio = 1 + iout_ratio;
mahphalke 1:c863d7e9e272 98 } else {
mahphalke 1:c863d7e9e272 99 calibration_iout_ratio = 1;
mahphalke 1:c863d7e9e272 100 }
mahphalke 1:c863d7e9e272 101 }
mahphalke 1:c863d7e9e272 102
mahphalke 1:c863d7e9e272 103
mahphalke 1:c863d7e9e272 104 /*!
mahphalke 1:c863d7e9e272 105 * @brief Convert the ADC raw value into equivalent PTC thermistor resistance
mahphalke 1:c863d7e9e272 106 * @param adc_raw[in]- ADC raw sample
mahphalke 1:c863d7e9e272 107 * @return PTC resistance value
mahphalke 1:c863d7e9e272 108 * @note PTC is biased with constant excitation current. Below formula
mahphalke 1:c863d7e9e272 109 * is based on ratiometric measurement, where fixed value of PTC RREF
mahphalke 1:c863d7e9e272 110 * (reference resistor) and gain is taken into account
mahphalke 1:c863d7e9e272 111 */
mahphalke 1:c863d7e9e272 112 static float convert_adc_raw_into_ptc_resistance(int32_t adc_raw)
mahphalke 1:c863d7e9e272 113 {
mahphalke 1:c863d7e9e272 114 float ptc_res;
mahphalke 1:c863d7e9e272 115
mahphalke 1:c863d7e9e272 116 /* Below equation is for bipolar inputs as all ADC configurations for
mahphalke 1:c863d7e9e272 117 * sensor measurement are having default bipolar mode */
mahphalke 1:c863d7e9e272 118 ptc_res = (((float)adc_raw - (1 << (AD7124_ADC_N_BITS - 1))) * PTC_RREF) / ((
mahphalke 1:c863d7e9e272 119 AD7124_PGA_GAIN(THERMISTOR_GAIN_VALUE)) * (1 << (AD7124_ADC_N_BITS - 1)));
mahphalke 1:c863d7e9e272 120
mahphalke 1:c863d7e9e272 121 return ptc_res;
mahphalke 1:c863d7e9e272 122 }
mahphalke 1:c863d7e9e272 123
mahphalke 1:c863d7e9e272 124
mahphalke 1:c863d7e9e272 125 /*!
mahphalke 1:c863d7e9e272 126 * @brief Convert the ADC raw value into equivalent NTC thermistor voltage
mahphalke 1:c863d7e9e272 127 * @param adc_raw[in]- ADC raw sample
mahphalke 1:c863d7e9e272 128 * @return NTC Thermistor voltage value
mahphalke 1:c863d7e9e272 129 * @note The NTC is biased with constant ADC reference voltage. Below formula
mahphalke 1:c863d7e9e272 130 * is based on ratiometric measurement, where fixed value of ADC REF
mahphalke 1:c863d7e9e272 131 * and gain is taken into account
mahphalke 1:c863d7e9e272 132 */
mahphalke 1:c863d7e9e272 133 static float convert_adc_raw_into_ntc_voltage(int32_t adc_raw)
mahphalke 1:c863d7e9e272 134 {
mahphalke 1:c863d7e9e272 135 float ntc_voltage;
mahphalke 1:c863d7e9e272 136
mahphalke 1:c863d7e9e272 137 /* Below equation is for bipolar inputs as all ADC configurations for
mahphalke 1:c863d7e9e272 138 * sensor measurement are having default bipolar mode */
mahphalke 1:c863d7e9e272 139 ntc_voltage = (((float)adc_raw - (1 << (AD7124_ADC_N_BITS - 1))) *
mahphalke 1:c863d7e9e272 140 AD7124_REF_VOLTAGE) / ((
mahphalke 1:c863d7e9e272 141 AD7124_PGA_GAIN(THERMISTOR_GAIN_VALUE)) * (1 << (AD7124_ADC_N_BITS - 1)));
mahphalke 1:c863d7e9e272 142
mahphalke 1:c863d7e9e272 143 return ntc_voltage;
mahphalke 1:c863d7e9e272 144 }
mahphalke 1:c863d7e9e272 145
mahphalke 1:c863d7e9e272 146
mahphalke 1:c863d7e9e272 147 /*!
mahphalke 1:c863d7e9e272 148 * @brief Convert the NTC thermistor voltage into equivalent resistance
mahphalke 1:c863d7e9e272 149 * @param voltage[in]- NTC Thermistor voltage
mahphalke 1:c863d7e9e272 150 * @return NTC Thermistor resistance value
mahphalke 1:c863d7e9e272 151 */
mahphalke 1:c863d7e9e272 152 static float convert_ntc_voltage_into_resistance(float ntc_voltage)
mahphalke 1:c863d7e9e272 153 {
mahphalke 1:c863d7e9e272 154 float ntc_resistance = (ntc_voltage * NTC_RSENSE) / (AD7124_REF_VOLTAGE -
mahphalke 1:c863d7e9e272 155 ntc_voltage);
mahphalke 1:c863d7e9e272 156 return ntc_resistance;
mahphalke 1:c863d7e9e272 157 }
mahphalke 1:c863d7e9e272 158
mahphalke 1:c863d7e9e272 159
mahphalke 1:c863d7e9e272 160 /**
mahphalke 1:c863d7e9e272 161 * @brief Converts raw ADC code to millivolts
mahphalke 1:c863d7e9e272 162 * @param raw_adc_code[in] Raw ADC code
mahphalke 1:c863d7e9e272 163 * @return voltage in millivolts
mahphalke 1:c863d7e9e272 164 * @details This converts the raw ADC code to millivolts for thermocouple channel,
mahphalke 1:c863d7e9e272 165 * based on the AD7124 Eval board configuration
mahphalke 1:c863d7e9e272 166 */
mahphalke 1:c863d7e9e272 167 static float convert_raw_adc_into_tc_mv(uint32_t raw_adc_code)
mahphalke 1:c863d7e9e272 168 {
mahphalke 1:c863d7e9e272 169 return (((((float)raw_adc_code - (1 << (AD7124_ADC_N_BITS - 1))) /
mahphalke 1:c863d7e9e272 170 (AD7124_PGA_GAIN(THERMOCOUPLE_GAIN_VALUE) *
mahphalke 1:c863d7e9e272 171 (1 << (AD7124_ADC_N_BITS - 1)))) * AD7124_REF_VOLTAGE) * 1000);
mahphalke 1:c863d7e9e272 172 }
mahphalke 1:c863d7e9e272 173
mahphalke 1:c863d7e9e272 174
mahphalke 3:f20f09251190 175
mahphalke 3:f20f09251190 176 /**
mahphalke 3:f20f09251190 177 * @brief Get the RTD reference resistor value
mahphalke 3:f20f09251190 178 * @return RTD reference resistor value
mahphalke 3:f20f09251190 179 */
mahphalke 3:f20f09251190 180 uint32_t get_rtd_rref(void)
mahphalke 3:f20f09251190 181 {
mahphalke 3:f20f09251190 182 return RTD_RREF;
mahphalke 3:f20f09251190 183 }
mahphalke 3:f20f09251190 184
mahphalke 3:f20f09251190 185
mahphalke 1:c863d7e9e272 186 /**
mahphalke 1:c863d7e9e272 187 * @brief Convert ADC raw value into TC temperature
mahphalke 1:c863d7e9e272 188 * @param tc_sample[in] Raw TC sample
mahphalke 1:c863d7e9e272 189 * @param cjc_sample[in] Raw CJC sample
mahphalke 1:c863d7e9e272 190 * @param cjc_sensor[in] CJC sensor type
mahphalke 3:f20f09251190 191 * @param cjc_temp[in] CJC temperature value
mahphalke 1:c863d7e9e272 192 * @return TC temperature
mahphalke 1:c863d7e9e272 193 */
mahphalke 1:c863d7e9e272 194 float get_tc_temperature(float tc_sample, float cjc_sample,
mahphalke 3:f20f09251190 195 cjc_sensor_type cjc_sensor, float *cjc_temp)
mahphalke 1:c863d7e9e272 196 {
mahphalke 1:c863d7e9e272 197 Thermocouple_Type_T tcSensor;
mahphalke 1:c863d7e9e272 198 float tc_mv;
mahphalke 1:c863d7e9e272 199 float tc_temperature;
mahphalke 1:c863d7e9e272 200 float cjc_temperature;
mahphalke 1:c863d7e9e272 201
mahphalke 1:c863d7e9e272 202 tc_mv = convert_raw_adc_into_tc_mv(tc_sample);
mahphalke 1:c863d7e9e272 203 tc_temperature = tcSensor.convert(tc_mv);
mahphalke 1:c863d7e9e272 204
mahphalke 1:c863d7e9e272 205 if (cjc_sensor == PT100_4WIRE_RTD) {
mahphalke 3:f20f09251190 206 cjc_temperature = get_rtd_temperature(cjc_sample, RTD_4WIRE_GAIN_VALUE);
mahphalke 1:c863d7e9e272 207 } else if (cjc_sensor == THERMISTOR_PTC_KY81_110) {
mahphalke 1:c863d7e9e272 208 cjc_temperature = get_ptc_thermistor_temperature(cjc_sample);
mahphalke 3:f20f09251190 209 } else if (cjc_sensor == PT1000_2WIRE_RTD) {
mahphalke 1:c863d7e9e272 210 PT1000 rtd_sensor;
mahphalke 1:c863d7e9e272 211 float rtd_resistance;
mahphalke 1:c863d7e9e272 212
mahphalke 3:f20f09251190 213 rtd_resistance = convert_adc_raw_into_rtd_resistance(cjc_sample,
mahphalke 3:f20f09251190 214 RTD_PT1000_GAIN_VALUE);
mahphalke 1:c863d7e9e272 215 cjc_temperature = rtd_sensor.convertResistanceToTemperature(rtd_resistance);
mahphalke 1:c863d7e9e272 216 } else {
mahphalke 1:c863d7e9e272 217 return 0;
mahphalke 1:c863d7e9e272 218 }
mahphalke 1:c863d7e9e272 219
mahphalke 3:f20f09251190 220 /* Get the CJC temperature */
mahphalke 3:f20f09251190 221 *cjc_temp = cjc_temperature;
mahphalke 3:f20f09251190 222
mahphalke 1:c863d7e9e272 223 /* NOTE The simplest approach of adding the CJC temperature to TC temperature is taken here.
mahphalke 1:c863d7e9e272 224 * A better method is to convert RTD back to thermocouple mV, and add that to TC value
mahphalke 1:c863d7e9e272 225 * then do the thermocouple to degC conversion.
mahphalke 1:c863d7e9e272 226 * */
mahphalke 1:c863d7e9e272 227 return (tc_temperature + cjc_temperature);
mahphalke 1:c863d7e9e272 228 }
mahphalke 1:c863d7e9e272 229
mahphalke 1:c863d7e9e272 230
mahphalke 1:c863d7e9e272 231 /**
mahphalke 1:c863d7e9e272 232 * @brief Convert ADC raw value into RTD temperature
mahphalke 1:c863d7e9e272 233 * @param rtd_sample[in] Raw RTD sample
mahphalke 3:f20f09251190 234 * @pram gain[in] RTD gain
mahphalke 1:c863d7e9e272 235 * @return RTD temperature
mahphalke 1:c863d7e9e272 236 * @note Fixed PT100 RTD sensor is used
mahphalke 1:c863d7e9e272 237 */
mahphalke 3:f20f09251190 238 float get_rtd_temperature(int32_t rtd_sample, uint8_t gain)
mahphalke 1:c863d7e9e272 239 {
mahphalke 1:c863d7e9e272 240 PT100 rtd_sensor;
mahphalke 1:c863d7e9e272 241 float rtd_resistance;
mahphalke 1:c863d7e9e272 242
mahphalke 3:f20f09251190 243 rtd_resistance = convert_adc_raw_into_rtd_resistance(rtd_sample, gain);
mahphalke 1:c863d7e9e272 244
mahphalke 1:c863d7e9e272 245 return rtd_sensor.convertResistanceToTemperature(rtd_resistance);
mahphalke 1:c863d7e9e272 246 }
mahphalke 1:c863d7e9e272 247
mahphalke 1:c863d7e9e272 248
mahphalke 1:c863d7e9e272 249 /**
mahphalke 1:c863d7e9e272 250 * @brief Convert ADC raw value into NTC temperature
mahphalke 1:c863d7e9e272 251 * @param ntc_sample[in] Raw NTC sample
mahphalke 1:c863d7e9e272 252 * @return NTC temperature
mahphalke 1:c863d7e9e272 253 * @note Fixed NTC 10K 44031RC sensor is used
mahphalke 1:c863d7e9e272 254 */
mahphalke 1:c863d7e9e272 255 float get_ntc_thermistor_temperature(int32_t ntc_sample)
mahphalke 1:c863d7e9e272 256 {
mahphalke 1:c863d7e9e272 257 ntc_10k_44031rc ntc_thermistor;
mahphalke 1:c863d7e9e272 258 float ntc_voltage;
mahphalke 1:c863d7e9e272 259 float ntc_resistance;
mahphalke 1:c863d7e9e272 260
mahphalke 1:c863d7e9e272 261 ntc_voltage = convert_adc_raw_into_ntc_voltage(ntc_sample);
mahphalke 1:c863d7e9e272 262 ntc_resistance = convert_ntc_voltage_into_resistance(ntc_voltage);
mahphalke 1:c863d7e9e272 263
mahphalke 1:c863d7e9e272 264 return ntc_thermistor.convert(ntc_resistance);
mahphalke 1:c863d7e9e272 265 }
mahphalke 1:c863d7e9e272 266
mahphalke 1:c863d7e9e272 267
mahphalke 1:c863d7e9e272 268 /**
mahphalke 1:c863d7e9e272 269 * @brief Convert ADC raw value into PTC temperature
mahphalke 1:c863d7e9e272 270 * @param ptc_sample[in] Raw PTC sample
mahphalke 1:c863d7e9e272 271 * @return PTC temperature
mahphalke 1:c863d7e9e272 272 * @note Fixed PTC KY81/110 Thermistor sensor is used
mahphalke 1:c863d7e9e272 273 */
mahphalke 1:c863d7e9e272 274 float get_ptc_thermistor_temperature(int32_t ptc_sample)
mahphalke 1:c863d7e9e272 275 {
mahphalke 1:c863d7e9e272 276 ptc_ky81_110 ptc_thermistor;
mahphalke 1:c863d7e9e272 277 float ptc_resistance;
mahphalke 1:c863d7e9e272 278
mahphalke 1:c863d7e9e272 279 ptc_resistance = convert_adc_raw_into_ptc_resistance(ptc_sample);
mahphalke 1:c863d7e9e272 280
mahphalke 1:c863d7e9e272 281 return ptc_thermistor.convert(ptc_resistance);
mahphalke 1:c863d7e9e272 282 }