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
- Committer:
- phonemacro
- Date:
- 2019-04-10
- Revision:
- 23:3fa31b45fa1a
- Parent:
- 20:c9805b01e814
File content as of revision 23:3fa31b45fa1a:
/******************************************************************************* * Copyright (C) 2019 Maxim Integrated Products, Inc., All Rights Reserved. * * Permission is hereby granted, free of charge, to any person obtaining a * copy of this software and associated documentation files (the "Software"), * to deal in the Software without restriction, including without limitation * the rights to use, copy, modify, merge, publish, distribute, sublicense, * and/or sell copies of the Software, and to permit persons to whom the * Software is furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included * in all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. * IN NO EVENT SHALL MAXIM INTEGRATED BE LIABLE FOR ANY CLAIM, DAMAGES * OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR * OTHER DEALINGS IN THE SOFTWARE. * * Except as contained in this notice, the name of Maxim Integrated * Products, Inc. shall not be used except as stated in the Maxim Integrated * Products, Inc. Branding Policy. * * The mere transfer of this software does not imply any licenses * of trade secrets, proprietary technology, copyrights, patents, * trademarks, maskwork rights, or any other form of intellectual * property whatsoever. Maxim Integrated Products, Inc. retains all * ownership rights. ******************************************************************************* */ #include "max31725.h" #include "max31725_c.h" #include "mbed.h" // #include "USBSerial.h" /******************************************************************************/ /* C version for MAX31725 driver */ /******************************************************************************/ /* @var max31725_write_address, max31725_read_address * @brief I2C address */ uint8_t max31725_write_address, max31725_read_address; /* @var max31875_extended_format * @brief Extended format, add 64°C to the temperature reading */ uint32_t max31725_extended_format; int max31725_init(uint8_t slave_address) { max31725_write_address = (slave_address <<1); max31725_read_address = ((slave_address << 1) | 1); max31725_extended_format = 0; return MAX31725_NO_ERROR; } /******************************************************************************/ int max31725_read_cfg_reg(uint8_t *value, I2C &i2c_bus) { int32_t ret; char data[1] = {0}; char reg = MAX31725_REG_CONFIGURATION; /* write to the Register Select, true is for repeated start */ ret = i2c_bus.write(max31725_write_address, ®, 1, true); if (ret == 0) { ret = i2c_bus.read(max31725_read_address, data, 1, false); if (ret == 0) { *value = data[0]; return MAX31725_NO_ERROR; } else { printf("%s: failed to read data: ret: %d\r\n", __func__, ret); } } else { printf("%s: failed to write to Register Select: ret: %d\r\n", __func__, ret); } return MAX31725_ERROR; } /******************************************************************************/ int max31725_read_reg16(int16_t *value, char reg, I2C &i2c_bus) { int32_t ret; char data[2] = {0, 0}; max31725_raw_data tmp; if (reg == MAX31725_REG_TEMPERATURE || reg == MAX31725_REG_THYST_LOW_TRIP || reg == MAX31725_REG_TOS_HIGH_TRIP) { /* write to the Register Select, true is for repeated start */ ret = i2c_bus.write(max31725_write_address, ®, 1, true); /* read the two bytes of data */ if (ret == 0) { ret = i2c_bus.read(max31725_read_address, data, 2, false); if (ret == 0) { tmp.msb = data[0]; tmp.lsb = data[1]; *value = tmp.swrd; return MAX31725_NO_ERROR; } else { printf( "%s: failed to read data: ret: %d\r\n", __func__, ret); } } else { printf("%s: failed to write to Register Select: ret: %d\r\n", __func__, ret); } } else { printf("%s: register address is not correct: register: %d\r\n", __func__, reg); } return MAX31725_ERROR; } float max31725_read_reg_as_temperature(uint8_t reg, I2C &i2c_bus) { max31725_raw_data tmp; float temperature; if (reg == MAX31725_REG_TEMPERATURE || reg == MAX31725_REG_THYST_LOW_TRIP || reg == MAX31725_REG_TOS_HIGH_TRIP) { max31725_read_reg16(&tmp.swrd, reg, i2c_bus); temperature = (float)tmp.swrd; /* values are 2's complement */ temperature *= MAX31725_CF_LSB; if (reg == MAX31725_REG_TEMPERATURE && max31725_extended_format) temperature += MAX31725_EXTENDED_FORMAT_OFFSET; return temperature; } else { printf("%s: register is invalid, %d r\n", __func__, reg); return 0; } } /******************************************************************************/ int max31725_write_reg16(int16_t value, char reg, I2C &i2c_bus) { int32_t ret; char cmd[3]; max31725_raw_data tmp; if (reg >= MAX31725_REG_THYST_LOW_TRIP && reg <= MAX31725_REG_MAX) { cmd[0] = reg; tmp.swrd = value; cmd[1] = tmp.msb; cmd[2] = tmp.lsb; ret = i2c_bus.write(max31725_write_address, cmd, 3, false); if (ret == 0) { return MAX31725_NO_ERROR; } else { printf("%s: I2C write error %d\r\n",__func__, ret); return MAX31725_ERROR; } } else { printf("%s: register value invalid %x\r\n",__func__, reg); return MAX31725_ERROR; } } int max31725_write_cfg_reg(uint8_t cfg, I2C &i2c_bus) { int32_t ret; char cmd[2]; cmd[0] = MAX31725_REG_CONFIGURATION; cmd[1] = cfg; ret = i2c_bus.write(max31725_write_address, cmd, 2, false); if (ret == 0) { max31725_extended_format = 0; if (cfg & MAX31725_CFG_EXTENDED_FORMAT) max31725_extended_format = 1; return MAX31725_NO_ERROR; } else { printf("%s: I2C write error %d\r\n",__func__, ret); return MAX31725_ERROR; } } int max31725_write_trip_low_thyst(float temperature, I2C &i2c_bus) { max31725_raw_data raw; temperature /= MAX31725_CF_LSB; raw.swrd = int16_t(temperature); return max31725_write_reg16(raw.swrd, MAX31725_REG_THYST_LOW_TRIP, i2c_bus); } int max31725_write_trip_high_tos(float temperature, I2C &i2c_bus) { max31725_raw_data raw; temperature /= MAX31725_CF_LSB; raw.swrd = int16_t(temperature); return max31725_write_reg16(raw.swrd, MAX31725_REG_TOS_HIGH_TRIP, i2c_bus); } float max31725_celsius_to_fahrenheit(float temp_c) { float temp_f; temp_f = ((temp_c * 9)/5) + 32; return temp_f; }