Diff: app/ad4130_temperature_sensor.cpp

Revision:

2:7b2b268ea49c

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/app/ad4130_temperature_sensor.cpp	Wed Jul 20 18:12:00 2022 +0530
@@ -0,0 +1,151 @@
+/***************************************************************************//*
+ * @file    ad4130_temperature_sensor.cpp
+ * @brief   AD4130 temperature sensor measurement functionality
+******************************************************************************
+ * Copyright (c) 2022 Analog Devices, Inc.
+ * All Rights Reserved.
+ *
+ * This software is proprietary to Analog Devices, Inc. and its licensors.
+ * By using this software you agree to the terms of the associated
+ * Analog Devices Software License Agreement.
+******************************************************************************/
+
+/******************************************************************************/
+/***************************** Include Files **********************************/
+/******************************************************************************/
+
+#include <stdint.h>
+#include <math.h>
+
+#include <thermocouple.h>
+#include <ntc_10k_44031.h>
+#include <ptxxx.h>
+#include "ad4130_temperature_sensor.h"
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif //  _cplusplus
+
+#include "app_config.h"
+#include "ad4130_support.h"
+
+#ifdef __cplusplus  // Closing extern c
+}
+#endif //  _cplusplus
+
+/******************************************************************************/
+/********************* Macros and Constants Definitions ***********************/
+/******************************************************************************/
+
+/* NTC thermistor Rsense value (in ohms) */
+#define NTC_RSENSE			10000U
+
+/* RTD Rref Resistance value (in ohms) */
+#define RTD_RREF			5110U
+
+/******************************************************************************/
+/******************** Variables and User Defined Data Types *******************/
+/******************************************************************************/
+
+/******************************************************************************/
+/************************** Functions Definitions *****************************/
+/******************************************************************************/
+
+/*!
+ * @brief	Convert the NTC thermistor voltage into equivalent resistance
+ * @param	ntc_voltage[in] - NTC Thermistor voltage
+ * @return	NTC Thermistor resistance value
+ * @note	The NTC is biased with constant ADC reference voltage. Below formula
+ *			is based on ratiometric measurement, where fixed value of ADC REF
+ *			and gain is taken into account
+ */
+static float convert_ntc_voltage_into_resistance(float ntc_voltage)
+{
+	return ((ntc_voltage * NTC_RSENSE) / (AD4170_1_25V_INT_REF_VOLTAGE -
+					      ntc_voltage));
+}
+
+/**
+ * @brief  	Convert ADC raw value into equivalent NTC temperature
+ * @param	dev[in] - Device instance
+ * @param	ntc_sample[in] - Raw ADC sample for NTC sensor
+ * @param	chn[in] - ADC channel
+ * @return	NTC temperature
+ * @note	Fixed NTC 10K 44031RC sensor is used
+ */
+float get_ntc_thermistor_temperature(void *dev, uint32_t ntc_sample,
+				     uint8_t chn)
+{
+	ntc_10k_44031rc ntc_thermistor;
+	float ntc_voltage;
+	float ntc_resistance;
+
+	ntc_voltage = convert_adc_sample_into_voltage(dev, ntc_sample, chn);
+	ntc_resistance = convert_ntc_voltage_into_resistance(ntc_voltage);
+
+	return ntc_thermistor.convert(ntc_resistance);
+}
+
+/**
+ * @brief  	Convert ADC raw value into equivalent RTD temperature
+ * @param	dev[in] - Device instance
+ * @param	rtd_sample[in] - Raw ADC sample for RTD sensor
+ * @pram	chn[in] - ADC channel
+ * @return	RTD temperature
+ * @note	Fixed PT100 RTD sensor is used
+ */
+float get_rtd_temperature(void *dev, uint32_t rtd_sample, uint8_t chn)
+{
+	PT100 rtd_sensor;
+	float rtd_resistance;
+
+	rtd_resistance = convert_adc_raw_into_rtd_resistance(dev, rtd_sample, RTD_RREF,
+			 chn);
+	return rtd_sensor.convertResistanceToTemperature(rtd_resistance);
+}
+
+/**
+ * @brief  	Convert ADC raw value into TC temperature
+ * @param	dev[in] - Device instance
+ * @param	tc_sample[in] - Raw TC sample
+ * @param	cjc_sample[in] - Raw CJC sample
+ * @param	tc_chn[in] - TC ADC channel
+ * @param	cjc_chn[in] - CJC ADC channel
+ * @param	cjc_temp[in, out] - CJC temperature value
+ * @return	TC temperature
+ * @note	T type thermocouple is used as default. For CJC, PT1000
+ *			RTD sensor is used as default.
+ */
+float get_tc_temperature(void *dev,
+			 uint32_t tc_sample, uint32_t cjc_sample,
+			 uint8_t tc_chn, uint8_t cjc_chn,
+			 float *cjc_temp)
+{
+	Thermocouple_Type_T tcSensor;
+	float tc_mv;
+	float tc_temperature;
+	float cjc_temperature;
+	PT1000 rtd_sensor;
+	float rtd_resistance;
+
+	tc_mv = convert_adc_sample_into_voltage(dev, tc_sample, tc_chn) * 1000;
+	tc_temperature = tcSensor.convert(tc_mv);
+
+#if defined(USE_CJC_AS_RTD)
+	rtd_resistance = convert_adc_raw_into_rtd_resistance(dev, cjc_sample, RTD_RREF,
+			 cjc_chn);
+	cjc_temperature = rtd_sensor.convertResistanceToTemperature(rtd_resistance);
+#else
+	cjc_temperature = get_ntc_thermistor_temperature(dev, cjc_sample, cjc_chn);
+#endif
+
+	/* Get the CJC temperature */
+	*cjc_temp = cjc_temperature;
+
+	/* NOTE The simplest approach of adding the CJC temperature to TC temperature is taken here.
+	 * A better method is to convert RTD back to thermocouple mV, and add that to TC value
+	 * then do the thermocouple to degC conversion.
+	 * */
+	return (tc_temperature + cjc_temperature);
+}