ntc_10k_44031.cpp

00001 /*!
00002  *****************************************************************************
00003   @file:  ntc_10k_44031.cpp
00004 
00005   @brief: This file contains functionality for 10K NTC 44021 model
00006 
00007   @details:
00008  -----------------------------------------------------------------------------
00009  Copyright (c) 2021 Analog Devices, Inc.  All rights reserved.
00010 
00011  This software is proprietary to Analog Devices, Inc. and its licensors.
00012  By using this software you agree to the terms of the associated
00013  Analog Devices Software License Agreement.
00014 
00015 *****************************************************************************/
00016 
00017 #include <math.h>
00018 #include "thermistor.h"
00019 #include "ntc_10k_44031.h"
00020 
00021 /* Convert the temperature using Beta factor specified for 44031 10K NTC */
00022 //#define   NTC_10K_44031_CONVERT_USING_BETA_VALUE
00023 
00024 #if defined(NTC_10K_44031_CONVERT_USING_BETA_VALUE)
00025 #define NTC_10K_44031_RESISTANCE_AT_25C     10000   // 10K
00026 #define NTC_10K_44031_ROOM_TEMP_IN_KELVIN   298.15
00027 #define NTC_10K_44031_BETA_VALUE            3694
00028 #endif
00029 
00030 #ifdef DEFINE_LOOKUP_TABLES
00031 /* 10K NTC look-up table. Values are resistance in ohm for temperature
00032  * range from -10 to 80C with +/-1C tolerance.
00033  * @note This function uses Steinhart-Hart equation for deriving look-up table.
00034 **/
00035 const uint32_t ntc_10k_44031rc::lut[] = {
00036     47561,  45285,  43131,  41091,  39158,  37327,  35591,  33946,  32385,
00037     30905,  29500,  28166,  26900,  25697,  24555,  23470,  22438,  21457,
00038     20524,  19637,  18792,  17989,  17224,  16495,  15801,  15140,  14510,
00039     13910,  13337,  12791,  12271,  11774,  11299,  10847,  10414,  10002,
00040     9607,   9231,   8870,   8526,   8197,   7882,   7581,   7293,   7018,
00041     6754,   6501,   6259,   6028,   5806,   5593,   5389,   5194,   5006,
00042     4827,   4654,   4489,   4331,   4178,   4032,   3892,   3757,   3628,
00043     3503,   3384,   3269,   3159,   3053,   2951,   2852,   2758,   2667,
00044     2580,   2496,   2415,   2337,   2262,   2189,   2120,   2053,   1988,
00045     1926,   1866,   1808,   1752,   1698,   1646,   1596,   1548,   1501,
00046     1456
00047 };
00048 #endif
00049 
00050 
00051 /*!
00052  * @brief   This is a constructor for ntc_10k_44031rc class
00053  * @return  none
00054  */
00055 ntc_10k_44031rc::ntc_10k_44031rc()
00056 {
00057     /* Coefficients of Steinhart-Hart equation for 10K NTC to convert
00058      * NTC resistance into equivalent temperature */
00059     ntc_10k_44031rc::coeff_A = 1.032*pow(10, -3);
00060     ntc_10k_44031rc::coeff_B = 2.387*pow(10, -4);
00061     ntc_10k_44031rc::coeff_C = 1.580*pow(10, -7);
00062 
00063 #ifdef DEFINE_LOOKUP_TABLES
00064     ntc_10k_44031rc::lut_offset = -10;  /* Min temperature obtained through LUT */
00065     ntc_10k_44031rc::lut_size = 90;     /* Temperature range defined in LUT
00066                                            [lut_offset : lut_size - lut_offset] */
00067 #endif
00068 }
00069 
00070 
00071 /*!
00072  * @brief   Convert the thermistor resistance into equivalent temperature using
00073  *          Steinhart-Hart equation Or Beta value for 10K 44031 NTC
00074  * @param   resistance[in] - thermistor resistance
00075  * @return  Thermistor temperature value in Celcius
00076  */
00077 float ntc_10k_44031rc::convert(const float resistance)
00078 {
00079 #if defined(NTC_10K_44031_CONVERT_USING_BETA_VALUE)
00080     float temperature;
00081     temperature = (1 / ((log(resistance / NTC_10K_44031_RESISTANCE_AT_25C) /
00082                  NTC_10K_44031_BETA_VALUE) + (1 / NTC_10K_44031_ROOM_TEMP_IN_KELVIN))) - 273.15;
00083     return temperature;
00084 #else
00085     return thermistor::convert(resistance, coeff_A, coeff_B, coeff_C);
00086 #endif
00087 }
00088 
00089 
00090 #ifdef DEFINE_LOOKUP_TABLES
00091 /*!
00092  * @brief   Convert the thermistor resistance into equivalent temperature using
00093  *          lookup table for 10K 44031 NTC
00094  * @param   resistance[in] - thermistor resistance
00095  * @return  Thermistor temperature value
00096  */
00097 float ntc_10k_44031rc::lookup(const float resistance)
00098 {
00099     return thermistor::lookup(lut, resistance, lut_size, lut_offset);
00100 }
00101 #endif