ptc_ky81_110.cpp

00001 /*!
00002  *****************************************************************************
00003   @file:  ptc_ky81_110.cpp
00004 
00005   @brief: This file contains functionality for PTC KY81/110 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 "thermistor.h"
00018 #include "ptc_ky81_110.h"
00019 
00020 #ifdef DEFINE_LOOKUP_TABLES
00021 /* PTC look-up table. Values are resistance in ohm for temperature
00022  * range from -10 to 80C with +/-1C tolerance.
00023  * @note This table is derived based on the look-up table specified
00024  *       in the datasheet of KY81/110 part. The linear interpolation
00025  *       has been used to obtain 1C step size.
00026 **/
00027 const uint32_t ptc_ky81_110::lut[] = {
00028     747, 753, 760, 767, 774, 781, 787, 794, 801, 808, 815, 822, 829, 836,
00029     843, 850, 857, 864, 871, 878, 886, 893, 901, 908, 916, 923, 931, 938,
00030     946, 953, 961, 968, 976, 984, 992, 1000, 1008, 1016, 1024, 1032, 1040,
00031     1048, 1056, 1064, 1072, 1081, 1089, 1097, 1105, 1113, 1122, 1130, 1139,
00032     1148, 1156, 1165, 1174, 1182, 1191, 1200, 1209, 1218, 1227, 1236, 1245,
00033     1254, 1263, 1272, 1281, 1290, 1299, 1308, 1317, 1326, 1336, 1345, 1354,
00034     1364, 1373, 1382, 1392, 1401, 1411, 1421, 1431, 1441, 1450, 1460, 1470,
00035     1480, 1490
00036 };
00037 #endif
00038 
00039 
00040 /*!
00041  * @brief   This is a constructor for ptc_ky81_110 class
00042  * @return  none
00043  */
00044 ptc_ky81_110::ptc_ky81_110()
00045 {
00046     temperature_coeff = 0.79;       /* Temperature coefficient for KY81/110 */
00047 
00048 #ifdef DEFINE_LOOKUP_TABLES
00049     ptc_ky81_110::lut_offset = -10; /* Min temperature obtained through LUT */
00050     ptc_ky81_110::lut_size = 90;    /* Temperature range defined in LUT
00051                                        [lut_offset : lut_size - lut_offset] */
00052 #endif
00053 }
00054 
00055 
00056 /*!
00057  * @brief   Convert the thermistor resistance into equivalent temperature
00058  * @param   resistance[in] - thermistor resistance
00059  * @return  Thermistor temperature value
00060  * @note    Resistance at room temperature is 1000 ohms (1K)
00061  */
00062 float ptc_ky81_110::convert(const float resistance)
00063 {
00064     return (((resistance - 1000) / 1000) * (100.0 / temperature_coeff)) + 25.0;
00065 }
00066 
00067 
00068 #ifdef DEFINE_LOOKUP_TABLES
00069 /*!
00070  * @brief   Convert the thermistor resistance into equivalent temperature using
00071  *          lookup table for KY81/110 NTC
00072  * @param   resistance[in] - thermistor resistance
00073  * @return  Thermistor temperature value
00074  */
00075 float ptc_ky81_110::lookup(const float resistance)
00076 {
00077     return thermistor::lookup(lut, resistance, lut_size, lut_offset);
00078 }
00079 #endif