Maxim Integrated / MAX31875_Temperature_Sensor_Low_Power

C code and C++ library, driver software for the low-power small WLP package MAX31875 temperature sensor. Code supports one-shot, shut-down/standby, hysteresis, alarm limits.

Dependents:   MAX31875_Temperature_Sensor_Small_WLP Click-Sensor-MAX31875 NuMaker-mbed-Sensor-MAX31875

max31875_cpp.cpp@6:61f3693edd6c, 2019-02-13 (annotated)

Committer:
phonemacro
Date:
Wed Feb 13 22:17:06 2019 +0000
Revision:
6:61f3693edd6c
Parent:
5:228e67722322 
correct initialization in write_trip_low, high.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
phonemacro 3:3528e660168c 1 /*******************************************************************************
phonemacro 3:3528e660168c 2 * Copyright (C) 2019 Maxim Integrated Products, Inc., All Rights Reserved.
phonemacro 3:3528e660168c 3 *
phonemacro 3:3528e660168c 4 * Permission is hereby granted, free of charge, to any person obtaining a
phonemacro 3:3528e660168c 5 * copy of this software and associated documentation files (the "Software"),
phonemacro 3:3528e660168c 6 * to deal in the Software without restriction, including without limitation
phonemacro 3:3528e660168c 7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
phonemacro 3:3528e660168c 8 * and/or sell copies of the Software, and to permit persons to whom the
phonemacro 3:3528e660168c 9 * Software is furnished to do so, subject to the following conditions:
phonemacro 3:3528e660168c 10 *
phonemacro 3:3528e660168c 11 * The above copyright notice and this permission notice shall be included
phonemacro 3:3528e660168c 12 * in all copies or substantial portions of the Software.
phonemacro 3:3528e660168c 13 *
phonemacro 3:3528e660168c 14 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
phonemacro 3:3528e660168c 15 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
phonemacro 3:3528e660168c 16 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
phonemacro 3:3528e660168c 17 * IN NO EVENT SHALL MAXIM INTEGRATED BE LIABLE FOR ANY CLAIM, DAMAGES
phonemacro 3:3528e660168c 18 * OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
phonemacro 3:3528e660168c 19 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
phonemacro 3:3528e660168c 20 * OTHER DEALINGS IN THE SOFTWARE.
phonemacro 3:3528e660168c 21 *
phonemacro 3:3528e660168c 22 * Except as contained in this notice, the name of Maxim Integrated
phonemacro 3:3528e660168c 23 * Products, Inc. shall not be used except as stated in the Maxim Integrated
phonemacro 3:3528e660168c 24 * Products, Inc. Branding Policy.
phonemacro 3:3528e660168c 25 *
phonemacro 3:3528e660168c 26 * The mere transfer of this software does not imply any licenses
phonemacro 3:3528e660168c 27 * of trade secrets, proprietary technology, copyrights, patents,
phonemacro 3:3528e660168c 28 * trademarks, maskwork rights, or any other form of intellectual
phonemacro 3:3528e660168c 29 * property whatsoever. Maxim Integrated Products, Inc. retains all
phonemacro 3:3528e660168c 30 * ownership rights.
phonemacro 3:3528e660168c 31 *******************************************************************************
phonemacro 3:3528e660168c 32 */
phonemacro 3:3528e660168c 33 #include "max31875.h"
phonemacro 3:3528e660168c 34 #include "max31875_cpp.h"
phonemacro 3:3528e660168c 35 #include "mbed.h"
phonemacro 3:3528e660168c 36 // #include "USBSerial.h"
phonemacro 3:3528e660168c 37
phonemacro 3:3528e660168c 38 /******************************************************************************
phonemacro 3:3528e660168c 39 * C++ version for MAX31875 driver *
phonemacro 3:3528e660168c 40 ******************************************************************************
phonemacro 3:3528e660168c 41 */
phonemacro 3:3528e660168c 42
phonemacro 3:3528e660168c 43 /******************************************************************************/
phonemacro 3:3528e660168c 44 MAX31875::MAX31875(I2C &i2c_bus, uint8_t slave_address):
phonemacro 3:3528e660168c 45 m_i2c(i2c_bus),
phonemacro 3:3528e660168c 46 m_write_address(slave_address <<1),
phonemacro 4:a27a0ee318bd 47 m_read_address ((slave_address << 1) | 1)
phonemacro 3:3528e660168c 48 {
phonemacro 4:a27a0ee318bd 49 m_extended_format = 0;
phonemacro 3:3528e660168c 50 }
phonemacro 3:3528e660168c 51
phonemacro 3:3528e660168c 52 /******************************************************************************/
phonemacro 3:3528e660168c 53 MAX31875::~MAX31875(void)
phonemacro 3:3528e660168c 54 {
phonemacro 3:3528e660168c 55 /** empty block */
phonemacro 3:3528e660168c 56 }
phonemacro 3:3528e660168c 57
phonemacro 3:3528e660168c 58 /******************************************************************************/
phonemacro 3:3528e660168c 59 int MAX31875::read_reg(uint16_t *value, char reg)
phonemacro 3:3528e660168c 60 {
phonemacro 3:3528e660168c 61 int32_t ret;
phonemacro 3:3528e660168c 62 char data[2] = {0, 0};
phonemacro 3:3528e660168c 63 max31875_raw_data tmp;
phonemacro 3:3528e660168c 64
phonemacro 3:3528e660168c 65 if (reg <= MAX31875_REG_MAX) {
phonemacro 3:3528e660168c 66 /* write to the Register Select */
phonemacro 3:3528e660168c 67 ret = m_i2c.write(m_write_address, &reg, 1, true);
phonemacro 3:3528e660168c 68 /* read the two bytes of data */
phonemacro 3:3528e660168c 69 if (ret == 0) {
phonemacro 3:3528e660168c 70 ret = m_i2c.read(m_read_address, data, 2, false);
phonemacro 3:3528e660168c 71 if (ret == 0) {
phonemacro 4:a27a0ee318bd 72 tmp.msb = data[0];
phonemacro 4:a27a0ee318bd 73 tmp.lsb = data[1];
phonemacro 4:a27a0ee318bd 74 *value = tmp.uwrd;
phonemacro 3:3528e660168c 75 return MAX31875_NO_ERROR;
phonemacro 3:3528e660168c 76 } else {
phonemacro 3:3528e660168c 77 printf(
phonemacro 3:3528e660168c 78 "%s: failed to read data: ret: %d\r\n", __func__, ret);
phonemacro 3:3528e660168c 79 }
phonemacro 3:3528e660168c 80 } else {
phonemacro 3:3528e660168c 81 printf("%s: failed to write to Register Select: ret: %d\r\n",
phonemacro 3:3528e660168c 82 __func__, ret);
phonemacro 3:3528e660168c 83 }
phonemacro 3:3528e660168c 84 } else {
phonemacro 3:3528e660168c 85 printf("%s: register address is not correct: register: %d\r\n",
phonemacro 3:3528e660168c 86 __func__, reg);
phonemacro 3:3528e660168c 87 }
phonemacro 3:3528e660168c 88 return MAX31875_ERROR;
phonemacro 3:3528e660168c 89 }
phonemacro 3:3528e660168c 90
phonemacro 3:3528e660168c 91 /******************************************************************************/
phonemacro 3:3528e660168c 92 float MAX31875::read_reg_as_temperature(uint8_t reg)
phonemacro 3:3528e660168c 93 {
phonemacro 3:3528e660168c 94 max31875_raw_data tmp;
phonemacro 3:3528e660168c 95 float temperature;
phonemacro 3:3528e660168c 96 if (reg == MAX31875_REG_TEMPERATURE ||
phonemacro 4:a27a0ee318bd 97 reg == MAX31875_REG_THYST_LOW_TRIP || reg == MAX31875_REG_TOS_HIGH_TRIP) {
phonemacro 3:3528e660168c 98 read_reg(&tmp.uwrd, reg);
phonemacro 4:a27a0ee318bd 99 temperature = (float)tmp.magnitude_bits;
phonemacro 3:3528e660168c 100 if (m_extended_format)
phonemacro 3:3528e660168c 101 temperature *= MAX31875_CF_EXTENDED_FORMAT;
phonemacro 3:3528e660168c 102 else
phonemacro 3:3528e660168c 103 temperature *= MAX31875_CF_NORMAL_FORMAT;
phonemacro 4:a27a0ee318bd 104 if (tmp.sign_bit)
phonemacro 4:a27a0ee318bd 105 temperature = -temperature;
phonemacro 3:3528e660168c 106 return temperature;
phonemacro 4:a27a0ee318bd 107
phonemacro 3:3528e660168c 108 } else {
phonemacro 3:3528e660168c 109 printf("%s: register is invalid, %d r\n", __func__, reg);
phonemacro 3:3528e660168c 110 return 0;
phonemacro 3:3528e660168c 111 }
phonemacro 3:3528e660168c 112 }
phonemacro 3:3528e660168c 113
phonemacro 3:3528e660168c 114 /******************************************************************************/
phonemacro 3:3528e660168c 115 int MAX31875::write_reg(uint16_t value, char reg)
phonemacro 3:3528e660168c 116 {
phonemacro 3:3528e660168c 117 int32_t ret;
phonemacro 3:3528e660168c 118 char cmd[3];
phonemacro 3:3528e660168c 119 max31875_raw_data tmp;
phonemacro 3:3528e660168c 120
phonemacro 3:3528e660168c 121 if (reg >= MAX31875_REG_CONFIGURATION && reg <= MAX31875_REG_MAX) {
phonemacro 3:3528e660168c 122 cmd[0] = reg;
phonemacro 3:3528e660168c 123 tmp.uwrd = value;
phonemacro 3:3528e660168c 124 cmd[1] = tmp.msb;
phonemacro 3:3528e660168c 125 cmd[2] = tmp.lsb;
phonemacro 3:3528e660168c 126 ret = m_i2c.write(m_write_address, cmd, 3, false);
phonemacro 3:3528e660168c 127 if (ret == 0) {
phonemacro 4:a27a0ee318bd 128 if (MAX31875_REG_CONFIGURATION == reg) {
phonemacro 3:3528e660168c 129 m_extended_format = 0;
phonemacro 4:a27a0ee318bd 130 if (tmp.uwrd & MAX31875_CFG_EXTENDED_FORMAT)
phonemacro 4:a27a0ee318bd 131 m_extended_format = 1;
phonemacro 4:a27a0ee318bd 132 }
phonemacro 3:3528e660168c 133 return MAX31875_NO_ERROR;
phonemacro 3:3528e660168c 134 } else {
phonemacro 3:3528e660168c 135 printf("%s: I2C write error %d\r\n",__func__, ret);
phonemacro 3:3528e660168c 136 return MAX31875_ERROR;
phonemacro 3:3528e660168c 137 }
phonemacro 3:3528e660168c 138 } else {
phonemacro 3:3528e660168c 139 printf("%s: register value invalid %x\r\n",__func__, reg);
phonemacro 3:3528e660168c 140 return MAX31875_ERROR;
phonemacro 3:3528e660168c 141 }
phonemacro 3:3528e660168c 142 }
phonemacro 3:3528e660168c 143
phonemacro 3:3528e660168c 144 /******************************************************************************/
phonemacro 3:3528e660168c 145 int MAX31875::write_cfg(uint16_t cfg)
phonemacro 3:3528e660168c 146 {
phonemacro 3:3528e660168c 147 return write_reg(cfg, MAX31875_REG_CONFIGURATION);
phonemacro 3:3528e660168c 148 }
phonemacro 3:3528e660168c 149
phonemacro 3:3528e660168c 150 /******************************************************************************/
phonemacro 3:3528e660168c 151 int MAX31875::write_trip_low(float temperature)
phonemacro 3:3528e660168c 152 {
phonemacro 3:3528e660168c 153 max31875_raw_data raw;
phonemacro 6:61f3693edd6c 154 raw.uwrd = 0;
phonemacro 4:a27a0ee318bd 155 if (temperature < 0) {
phonemacro 4:a27a0ee318bd 156 raw.sign_bit = 1;
phonemacro 4:a27a0ee318bd 157 temperature = -temperature;
phonemacro 4:a27a0ee318bd 158 }
phonemacro 3:3528e660168c 159 if (m_extended_format)
phonemacro 3:3528e660168c 160 temperature /= MAX31875_CF_EXTENDED_FORMAT;
phonemacro 3:3528e660168c 161 else
phonemacro 3:3528e660168c 162 temperature /= MAX31875_CF_NORMAL_FORMAT;
phonemacro 6:61f3693edd6c 163 raw.magnitude_bits = uint16_t(temperature);
phonemacro 4:a27a0ee318bd 164 return write_reg(raw.uwrd, MAX31875_REG_THYST_LOW_TRIP);
phonemacro 3:3528e660168c 165 }
phonemacro 3:3528e660168c 166
phonemacro 3:3528e660168c 167 /******************************************************************************/
phonemacro 3:3528e660168c 168 int MAX31875::write_trip_high(float temperature)
phonemacro 3:3528e660168c 169 {
phonemacro 3:3528e660168c 170 max31875_raw_data raw;
phonemacro 6:61f3693edd6c 171 raw.uwrd = 0;
phonemacro 4:a27a0ee318bd 172 if (temperature < 0) {
phonemacro 4:a27a0ee318bd 173 raw.sign_bit = 1;
phonemacro 4:a27a0ee318bd 174 temperature = -temperature;
phonemacro 4:a27a0ee318bd 175 }
phonemacro 3:3528e660168c 176 if (m_extended_format)
phonemacro 3:3528e660168c 177 temperature /= MAX31875_CF_EXTENDED_FORMAT;
phonemacro 3:3528e660168c 178 else
phonemacro 3:3528e660168c 179 temperature /= MAX31875_CF_NORMAL_FORMAT;
phonemacro 6:61f3693edd6c 180 raw.magnitude_bits = uint16_t(temperature);
phonemacro 4:a27a0ee318bd 181 return write_reg(raw.uwrd, MAX31875_REG_TOS_HIGH_TRIP);
phonemacro 3:3528e660168c 182 }
phonemacro 3:3528e660168c 183
phonemacro 3:3528e660168c 184 /******************************************************************************/
phonemacro 3:3528e660168c 185 float MAX31875::celsius_to_fahrenheit(float temp_c)
phonemacro 3:3528e660168c 186 {
phonemacro 3:3528e660168c 187 float temp_f;
phonemacro 3:3528e660168c 188 temp_f = ((temp_c * 9)/5) + 32;
phonemacro 3:3528e660168c 189 return temp_f;
phonemacro 3:3528e660168c 190 }