David Jung / MAX31725_Accurate_Temperature_Sensor

The MAX31725, MAX31726 temperature sensors provides temperature measurements with an accuracy of up to +-0.5°C. Extended format allows for high temperature readings up to 150°C. The MAX31725 can operate in a low powered mode by utilizing the shutdown and one-shot mode. Supports two-wire serial, I2C bus communications. 8-pin TQDFN 3x3 mm package. Accuracy is +-0.5°C from -40°C to +105°C (-40°F to +221°). The operating temperature range is -55°C to +150°C (-67°F to +302°). VDD is 2.5V to 3.7V.

Dependents:   MAX31725_High_Temperature_Accurate_IC

max31725_c.cpp@23:3fa31b45fa1a, 2019-04-10 (annotated)

Committer:
phonemacro
Date:
Wed Apr 10 17:07:21 2019 +0000
Revision:
23:3fa31b45fa1a
Parent:
20:c9805b01e814 
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phonemacro 20:c9805b01e814 1 /*******************************************************************************
phonemacro 20:c9805b01e814 2 * Copyright (C) 2019 Maxim Integrated Products, Inc., All Rights Reserved.
phonemacro 20:c9805b01e814 3 *
phonemacro 20:c9805b01e814 4 * Permission is hereby granted, free of charge, to any person obtaining a
phonemacro 20:c9805b01e814 5 * copy of this software and associated documentation files (the "Software"),
phonemacro 20:c9805b01e814 6 * to deal in the Software without restriction, including without limitation
phonemacro 20:c9805b01e814 7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
phonemacro 20:c9805b01e814 8 * and/or sell copies of the Software, and to permit persons to whom the
phonemacro 20:c9805b01e814 9 * Software is furnished to do so, subject to the following conditions:
phonemacro 20:c9805b01e814 10 *
phonemacro 20:c9805b01e814 11 * The above copyright notice and this permission notice shall be included
phonemacro 20:c9805b01e814 12 * in all copies or substantial portions of the Software.
phonemacro 20:c9805b01e814 13 *
phonemacro 20:c9805b01e814 14 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
phonemacro 20:c9805b01e814 15 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
phonemacro 20:c9805b01e814 16 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
phonemacro 20:c9805b01e814 17 * IN NO EVENT SHALL MAXIM INTEGRATED BE LIABLE FOR ANY CLAIM, DAMAGES
phonemacro 20:c9805b01e814 18 * OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
phonemacro 20:c9805b01e814 19 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
phonemacro 20:c9805b01e814 20 * OTHER DEALINGS IN THE SOFTWARE.
phonemacro 20:c9805b01e814 21 *
phonemacro 20:c9805b01e814 22 * Except as contained in this notice, the name of Maxim Integrated
phonemacro 20:c9805b01e814 23 * Products, Inc. shall not be used except as stated in the Maxim Integrated
phonemacro 20:c9805b01e814 24 * Products, Inc. Branding Policy.
phonemacro 20:c9805b01e814 25 *
phonemacro 20:c9805b01e814 26 * The mere transfer of this software does not imply any licenses
phonemacro 20:c9805b01e814 27 * of trade secrets, proprietary technology, copyrights, patents,
phonemacro 20:c9805b01e814 28 * trademarks, maskwork rights, or any other form of intellectual
phonemacro 20:c9805b01e814 29 * property whatsoever. Maxim Integrated Products, Inc. retains all
phonemacro 20:c9805b01e814 30 * ownership rights.
phonemacro 20:c9805b01e814 31 *******************************************************************************
phonemacro 20:c9805b01e814 32 */
phonemacro 20:c9805b01e814 33 #include "max31725.h"
phonemacro 20:c9805b01e814 34 #include "max31725_c.h"
phonemacro 20:c9805b01e814 35 #include "mbed.h"
phonemacro 20:c9805b01e814 36 // #include "USBSerial.h"
phonemacro 20:c9805b01e814 37
phonemacro 20:c9805b01e814 38
phonemacro 20:c9805b01e814 39 /******************************************************************************/
phonemacro 20:c9805b01e814 40 /* C version for MAX31725 driver */
phonemacro 20:c9805b01e814 41 /******************************************************************************/
phonemacro 20:c9805b01e814 42
phonemacro 20:c9805b01e814 43 /* @var max31725_write_address, max31725_read_address
phonemacro 20:c9805b01e814 44 * @brief I2C address
phonemacro 20:c9805b01e814 45 */
phonemacro 20:c9805b01e814 46 uint8_t max31725_write_address, max31725_read_address;
phonemacro 20:c9805b01e814 47
phonemacro 20:c9805b01e814 48 /* @var max31875_extended_format
phonemacro 20:c9805b01e814 49 * @brief Extended format, add 64°C to the temperature reading
phonemacro 20:c9805b01e814 50 */
phonemacro 20:c9805b01e814 51 uint32_t max31725_extended_format;
phonemacro 20:c9805b01e814 52
phonemacro 20:c9805b01e814 53 int max31725_init(uint8_t slave_address)
phonemacro 20:c9805b01e814 54 {
phonemacro 20:c9805b01e814 55 max31725_write_address = (slave_address <<1);
phonemacro 20:c9805b01e814 56 max31725_read_address = ((slave_address << 1) | 1);
phonemacro 20:c9805b01e814 57 max31725_extended_format = 0;
phonemacro 20:c9805b01e814 58 return MAX31725_NO_ERROR;
phonemacro 20:c9805b01e814 59 }
phonemacro 20:c9805b01e814 60
phonemacro 20:c9805b01e814 61 /******************************************************************************/
phonemacro 20:c9805b01e814 62 int max31725_read_cfg_reg(uint8_t *value, I2C &i2c_bus)
phonemacro 20:c9805b01e814 63 {
phonemacro 20:c9805b01e814 64 int32_t ret;
phonemacro 20:c9805b01e814 65 char data[1] = {0};
phonemacro 20:c9805b01e814 66 char reg = MAX31725_REG_CONFIGURATION;
phonemacro 20:c9805b01e814 67
phonemacro 20:c9805b01e814 68 /* write to the Register Select, true is for repeated start */
phonemacro 20:c9805b01e814 69 ret = i2c_bus.write(max31725_write_address, &reg, 1, true);
phonemacro 20:c9805b01e814 70 if (ret == 0) {
phonemacro 20:c9805b01e814 71 ret = i2c_bus.read(max31725_read_address, data, 1, false);
phonemacro 20:c9805b01e814 72 if (ret == 0) {
phonemacro 20:c9805b01e814 73 *value = data[0];
phonemacro 20:c9805b01e814 74 return MAX31725_NO_ERROR;
phonemacro 20:c9805b01e814 75 } else {
phonemacro 20:c9805b01e814 76 printf("%s: failed to read data: ret: %d\r\n", __func__, ret);
phonemacro 20:c9805b01e814 77 }
phonemacro 20:c9805b01e814 78 } else {
phonemacro 20:c9805b01e814 79 printf("%s: failed to write to Register Select: ret: %d\r\n",
phonemacro 20:c9805b01e814 80 __func__, ret);
phonemacro 20:c9805b01e814 81 }
phonemacro 20:c9805b01e814 82 return MAX31725_ERROR;
phonemacro 20:c9805b01e814 83 }
phonemacro 20:c9805b01e814 84
phonemacro 20:c9805b01e814 85
phonemacro 20:c9805b01e814 86 /******************************************************************************/
phonemacro 20:c9805b01e814 87 int max31725_read_reg16(int16_t *value, char reg, I2C &i2c_bus)
phonemacro 20:c9805b01e814 88 {
phonemacro 20:c9805b01e814 89 int32_t ret;
phonemacro 20:c9805b01e814 90 char data[2] = {0, 0};
phonemacro 20:c9805b01e814 91 max31725_raw_data tmp;
phonemacro 20:c9805b01e814 92
phonemacro 20:c9805b01e814 93 if (reg == MAX31725_REG_TEMPERATURE ||
phonemacro 20:c9805b01e814 94 reg == MAX31725_REG_THYST_LOW_TRIP || reg == MAX31725_REG_TOS_HIGH_TRIP) {
phonemacro 20:c9805b01e814 95 /* write to the Register Select, true is for repeated start */
phonemacro 20:c9805b01e814 96 ret = i2c_bus.write(max31725_write_address, &reg, 1, true);
phonemacro 20:c9805b01e814 97 /* read the two bytes of data */
phonemacro 20:c9805b01e814 98 if (ret == 0) {
phonemacro 20:c9805b01e814 99 ret = i2c_bus.read(max31725_read_address, data, 2, false);
phonemacro 20:c9805b01e814 100 if (ret == 0) {
phonemacro 20:c9805b01e814 101 tmp.msb = data[0];
phonemacro 20:c9805b01e814 102 tmp.lsb = data[1];
phonemacro 20:c9805b01e814 103 *value = tmp.swrd;
phonemacro 20:c9805b01e814 104 return MAX31725_NO_ERROR;
phonemacro 20:c9805b01e814 105 } else {
phonemacro 20:c9805b01e814 106 printf(
phonemacro 20:c9805b01e814 107 "%s: failed to read data: ret: %d\r\n", __func__, ret);
phonemacro 20:c9805b01e814 108 }
phonemacro 20:c9805b01e814 109 } else {
phonemacro 20:c9805b01e814 110 printf("%s: failed to write to Register Select: ret: %d\r\n",
phonemacro 20:c9805b01e814 111 __func__, ret);
phonemacro 20:c9805b01e814 112 }
phonemacro 20:c9805b01e814 113 } else {
phonemacro 20:c9805b01e814 114 printf("%s: register address is not correct: register: %d\r\n",
phonemacro 20:c9805b01e814 115 __func__, reg);
phonemacro 20:c9805b01e814 116 }
phonemacro 20:c9805b01e814 117 return MAX31725_ERROR;
phonemacro 20:c9805b01e814 118 }
phonemacro 20:c9805b01e814 119
phonemacro 20:c9805b01e814 120 float max31725_read_reg_as_temperature(uint8_t reg, I2C &i2c_bus)
phonemacro 20:c9805b01e814 121 {
phonemacro 20:c9805b01e814 122 max31725_raw_data tmp;
phonemacro 20:c9805b01e814 123 float temperature;
phonemacro 20:c9805b01e814 124 if (reg == MAX31725_REG_TEMPERATURE ||
phonemacro 20:c9805b01e814 125 reg == MAX31725_REG_THYST_LOW_TRIP || reg == MAX31725_REG_TOS_HIGH_TRIP) {
phonemacro 20:c9805b01e814 126 max31725_read_reg16(&tmp.swrd, reg, i2c_bus);
phonemacro 20:c9805b01e814 127 temperature = (float)tmp.swrd; /* values are 2's complement */
phonemacro 20:c9805b01e814 128 temperature *= MAX31725_CF_LSB;
phonemacro 20:c9805b01e814 129 if (reg == MAX31725_REG_TEMPERATURE && max31725_extended_format)
phonemacro 20:c9805b01e814 130 temperature += MAX31725_EXTENDED_FORMAT_OFFSET;
phonemacro 20:c9805b01e814 131 return temperature;
phonemacro 20:c9805b01e814 132 } else {
phonemacro 20:c9805b01e814 133 printf("%s: register is invalid, %d r\n", __func__, reg);
phonemacro 20:c9805b01e814 134 return 0;
phonemacro 20:c9805b01e814 135 }
phonemacro 20:c9805b01e814 136 }
phonemacro 20:c9805b01e814 137
phonemacro 20:c9805b01e814 138
phonemacro 20:c9805b01e814 139 /******************************************************************************/
phonemacro 20:c9805b01e814 140 int max31725_write_reg16(int16_t value, char reg, I2C &i2c_bus)
phonemacro 20:c9805b01e814 141 {
phonemacro 20:c9805b01e814 142 int32_t ret;
phonemacro 20:c9805b01e814 143 char cmd[3];
phonemacro 20:c9805b01e814 144 max31725_raw_data tmp;
phonemacro 20:c9805b01e814 145
phonemacro 20:c9805b01e814 146 if (reg >= MAX31725_REG_THYST_LOW_TRIP && reg <= MAX31725_REG_MAX) {
phonemacro 20:c9805b01e814 147 cmd[0] = reg;
phonemacro 20:c9805b01e814 148 tmp.swrd = value;
phonemacro 20:c9805b01e814 149 cmd[1] = tmp.msb;
phonemacro 20:c9805b01e814 150 cmd[2] = tmp.lsb;
phonemacro 20:c9805b01e814 151 ret = i2c_bus.write(max31725_write_address, cmd, 3, false);
phonemacro 20:c9805b01e814 152 if (ret == 0) {
phonemacro 20:c9805b01e814 153 return MAX31725_NO_ERROR;
phonemacro 20:c9805b01e814 154 } else {
phonemacro 20:c9805b01e814 155 printf("%s: I2C write error %d\r\n",__func__, ret);
phonemacro 20:c9805b01e814 156 return MAX31725_ERROR;
phonemacro 20:c9805b01e814 157 }
phonemacro 20:c9805b01e814 158 } else {
phonemacro 20:c9805b01e814 159 printf("%s: register value invalid %x\r\n",__func__, reg);
phonemacro 20:c9805b01e814 160 return MAX31725_ERROR;
phonemacro 20:c9805b01e814 161 }
phonemacro 20:c9805b01e814 162 }
phonemacro 20:c9805b01e814 163
phonemacro 20:c9805b01e814 164
phonemacro 20:c9805b01e814 165 int max31725_write_cfg_reg(uint8_t cfg, I2C &i2c_bus)
phonemacro 20:c9805b01e814 166 {
phonemacro 20:c9805b01e814 167 int32_t ret;
phonemacro 20:c9805b01e814 168 char cmd[2];
phonemacro 20:c9805b01e814 169
phonemacro 20:c9805b01e814 170 cmd[0] = MAX31725_REG_CONFIGURATION;
phonemacro 20:c9805b01e814 171 cmd[1] = cfg;
phonemacro 20:c9805b01e814 172 ret = i2c_bus.write(max31725_write_address, cmd, 2, false);
phonemacro 20:c9805b01e814 173 if (ret == 0) {
phonemacro 20:c9805b01e814 174 max31725_extended_format = 0;
phonemacro 20:c9805b01e814 175 if (cfg & MAX31725_CFG_EXTENDED_FORMAT)
phonemacro 20:c9805b01e814 176 max31725_extended_format = 1;
phonemacro 20:c9805b01e814 177
phonemacro 20:c9805b01e814 178 return MAX31725_NO_ERROR;
phonemacro 20:c9805b01e814 179 } else {
phonemacro 20:c9805b01e814 180 printf("%s: I2C write error %d\r\n",__func__, ret);
phonemacro 20:c9805b01e814 181 return MAX31725_ERROR;
phonemacro 20:c9805b01e814 182 }
phonemacro 20:c9805b01e814 183 }
phonemacro 20:c9805b01e814 184
phonemacro 20:c9805b01e814 185
phonemacro 20:c9805b01e814 186 int max31725_write_trip_low_thyst(float temperature, I2C &i2c_bus)
phonemacro 20:c9805b01e814 187 {
phonemacro 20:c9805b01e814 188 max31725_raw_data raw;
phonemacro 20:c9805b01e814 189 temperature /= MAX31725_CF_LSB;
phonemacro 20:c9805b01e814 190 raw.swrd = int16_t(temperature);
phonemacro 20:c9805b01e814 191 return max31725_write_reg16(raw.swrd, MAX31725_REG_THYST_LOW_TRIP, i2c_bus);
phonemacro 20:c9805b01e814 192 }
phonemacro 20:c9805b01e814 193
phonemacro 20:c9805b01e814 194
phonemacro 20:c9805b01e814 195 int max31725_write_trip_high_tos(float temperature, I2C &i2c_bus)
phonemacro 20:c9805b01e814 196 {
phonemacro 20:c9805b01e814 197 max31725_raw_data raw;
phonemacro 20:c9805b01e814 198 temperature /= MAX31725_CF_LSB;
phonemacro 20:c9805b01e814 199 raw.swrd = int16_t(temperature);
phonemacro 20:c9805b01e814 200 return max31725_write_reg16(raw.swrd, MAX31725_REG_TOS_HIGH_TRIP, i2c_bus);
phonemacro 20:c9805b01e814 201 }
phonemacro 20:c9805b01e814 202
phonemacro 20:c9805b01e814 203
phonemacro 20:c9805b01e814 204 float max31725_celsius_to_fahrenheit(float temp_c)
phonemacro 20:c9805b01e814 205 {
phonemacro 20:c9805b01e814 206 float temp_f;
phonemacro 20:c9805b01e814 207 temp_f = ((temp_c * 9)/5) + 32;
phonemacro 20:c9805b01e814 208 return temp_f;
phonemacro 20:c9805b01e814 209 }