Diff: app/ad7124_temperature_sensor.cpp

Revision:

3:f20f09251190

Parent:

1:c863d7e9e272

--- a/app/ad7124_temperature_sensor.cpp	Mon Feb 22 05:16:41 2021 +0000
+++ b/app/ad7124_temperature_sensor.cpp	Fri Mar 19 14:34:05 2021 +0530
@@ -42,10 +42,13 @@
 /******************************************************************************/
 
 /* NTC thermistor Rsense value (in ohms) */
-#define NTC_RSENSE			10000
+#define NTC_RSENSE			10000U
+
+/* RTD Rref Resistance value (in ohms) */
+#define RTD_RREF			5110U
 
 /* PTC thermistor Ref Resistance value (in ohms) */
-#define PTC_RREF			5110
+#define PTC_RREF			5110U
 
 /******************************************************************************/
 /******************** Variables and User Defined Data Types *******************/
@@ -61,12 +64,13 @@
 /*!
  * @brief	Convert the ADC raw value into equivalent RTD resistance
  * @param	adc_raw[in]- ADC raw sample
+ * @param	gain[in] - RTD gain
  * @return	RTD resistance value
  * @note	RTD is biased with constant excitation current. Below formula
  *			is based on ratiometric measurement, where fixed value of RTD RREF
  *			(reference resistor) and gain is taken into account
  */
-static float convert_adc_raw_into_rtd_resistance(int32_t adc_raw)
+static float convert_adc_raw_into_rtd_resistance(int32_t adc_raw, uint8_t gain)
 {
 	float rtd_res;
 
@@ -74,7 +78,7 @@
 	 * sensor measurement are having default bipolar mode */
 	rtd_res = (((float)adc_raw - (1 << (AD7124_ADC_N_BITS - 1))) *
 		   (calibration_iout_ratio * RTD_RREF)) / ((
-					   AD7124_PGA_GAIN(RTD_GAIN_VALUE)) * (1 << (AD7124_ADC_N_BITS - 1)));
+					   AD7124_PGA_GAIN(gain)) * (1 << (AD7124_ADC_N_BITS - 1)));
 
 	return rtd_res;
 }
@@ -168,15 +172,27 @@
 }
 
 
+
+/**
+ * @brief  	Get the RTD reference resistor value
+ * @return	RTD reference resistor value
+ */
+uint32_t get_rtd_rref(void)
+{
+	return RTD_RREF;
+}
+
+
 /**
  * @brief  	Convert ADC raw value into TC temperature
  * @param	tc_sample[in] Raw TC sample
  * @param	cjc_sample[in] Raw CJC sample
  * @param	cjc_sensor[in] CJC sensor type
+ * @param	cjc_temp[in] CJC temperature value
  * @return	TC temperature
  */
 float get_tc_temperature(float tc_sample, float cjc_sample,
-			 cjc_sensor_type cjc_sensor)
+			 cjc_sensor_type cjc_sensor, float *cjc_temp)
 {
 	Thermocouple_Type_T tcSensor;
 	float tc_mv;
@@ -187,19 +203,23 @@
 	tc_temperature = tcSensor.convert(tc_mv);
 
 	if (cjc_sensor == PT100_4WIRE_RTD) {
-		cjc_temperature = get_rtd_temperature(cjc_sample);
+		cjc_temperature = get_rtd_temperature(cjc_sample, RTD_4WIRE_GAIN_VALUE);
 	} else if (cjc_sensor == THERMISTOR_PTC_KY81_110) {
 		cjc_temperature = get_ptc_thermistor_temperature(cjc_sample);
-	} else if (cjc_sensor == PT1000_4WIRE_RTD) {
+	} else if (cjc_sensor == PT1000_2WIRE_RTD) {
 		PT1000 rtd_sensor;
 		float rtd_resistance;
 
-		rtd_resistance = convert_adc_raw_into_rtd_resistance(cjc_sample);
+		rtd_resistance = convert_adc_raw_into_rtd_resistance(cjc_sample,
+				 RTD_PT1000_GAIN_VALUE);
 		cjc_temperature = rtd_sensor.convertResistanceToTemperature(rtd_resistance);
 	} else {
 		return 0;
 	}
 
+	/* 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.
@@ -211,15 +231,16 @@
 /**
  * @brief  	Convert ADC raw value into RTD temperature
  * @param	rtd_sample[in] Raw RTD sample
+ * @pram	gain[in]  RTD gain
  * @return	RTD temperature
  * @note	Fixed PT100 RTD sensor is used
  */
-float get_rtd_temperature(int32_t rtd_sample)
+float get_rtd_temperature(int32_t rtd_sample, uint8_t gain)
 {
 	PT100 rtd_sensor;
 	float rtd_resistance;
 
-	rtd_resistance = convert_adc_raw_into_rtd_resistance(rtd_sample);
+	rtd_resistance = convert_adc_raw_into_rtd_resistance(rtd_sample, gain);
 
 	return rtd_sensor.convertResistanceToTemperature(rtd_resistance);
 }
@@ -259,4 +280,3 @@
 
 	return ptc_thermistor.convert(ptc_resistance);
 }
-