Neil Thiessen / LM75B

A feature complete driver for the LM75B temperature sensor from NXP.

Dependents:   app-board-TempAlarm LM75B IoTWorkshopSensors EduRobot ... more

LM75B.cpp@1:3da8df4319e8, 2013-07-31 (annotated)

Committer:
neilt6
Date:
Wed Jul 31 22:11:31 2013 +0000
Revision:
1:3da8df4319e8
Parent:
0:557a92280097
Child:
2:9ecc39b2ca70
Updated license to MIT

Who changed what in which revision?

UserRevisionLine numberNew contents of line
neilt6 1:3da8df4319e8 1 /* Copyright (c) 2013 Neil Thiessen, MIT License
neilt6 0:557a92280097 2 *
neilt6 1:3da8df4319e8 3 * Permission is hereby granted, free of charge, to any person obtaining a copy of this software
neilt6 1:3da8df4319e8 4 * and associated documentation files (the "Software"), to deal in the Software without restriction,
neilt6 1:3da8df4319e8 5 * including without limitation the rights to use, copy, modify, merge, publish, distribute,
neilt6 1:3da8df4319e8 6 * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
neilt6 0:557a92280097 7 * furnished to do so, subject to the following conditions:
neilt6 0:557a92280097 8 *
neilt6 1:3da8df4319e8 9 * The above copyright notice and this permission notice shall be included in all copies or
neilt6 1:3da8df4319e8 10 * substantial portions of the Software.
neilt6 0:557a92280097 11 *
neilt6 1:3da8df4319e8 12 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
neilt6 1:3da8df4319e8 13 * BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
neilt6 1:3da8df4319e8 14 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
neilt6 1:3da8df4319e8 15 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
neilt6 1:3da8df4319e8 16 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
neilt6 0:557a92280097 17 */
neilt6 0:557a92280097 18
neilt6 0:557a92280097 19 #include "LM75B.h"
neilt6 0:557a92280097 20 #include "mbed.h"
neilt6 0:557a92280097 21
neilt6 0:557a92280097 22 LM75B::LM75B(PinName sda, PinName scl, int addr) : _i2c(sda, scl)
neilt6 0:557a92280097 23 {
neilt6 0:557a92280097 24 //Set the internal device address
neilt6 0:557a92280097 25 _addr = addr;
neilt6 0:557a92280097 26 }
neilt6 0:557a92280097 27
neilt6 0:557a92280097 28 LM75B_Power_t LM75B::getPowerMode(void)
neilt6 0:557a92280097 29 {
neilt6 0:557a92280097 30 //Read the 8-bit register value
neilt6 0:557a92280097 31 char value = _read8(LM75B_REG_CONF);
neilt6 0:557a92280097 32
neilt6 0:557a92280097 33 //Return the status of the SHUTDOWN bit
neilt6 0:557a92280097 34 if (value & (1 << 0))
neilt6 0:557a92280097 35 return LM75B_Power_Shutdown;
neilt6 0:557a92280097 36 else
neilt6 0:557a92280097 37 return LM75B_Power_Normal;
neilt6 0:557a92280097 38 }
neilt6 0:557a92280097 39
neilt6 0:557a92280097 40 void LM75B::setPowerMode(LM75B_Power_t mode)
neilt6 0:557a92280097 41 {
neilt6 0:557a92280097 42 //Read the current 8-bit register value
neilt6 0:557a92280097 43 char value = _read8(LM75B_REG_CONF);
neilt6 0:557a92280097 44
neilt6 0:557a92280097 45 //Set or clear the SHUTDOWN bit
neilt6 0:557a92280097 46 if (mode == LM75B_Power_Shutdown)
neilt6 0:557a92280097 47 value |= (1 << 0);
neilt6 0:557a92280097 48 else
neilt6 0:557a92280097 49 value &= ~(1 << 0);
neilt6 0:557a92280097 50
neilt6 0:557a92280097 51 //Write the value back out
neilt6 0:557a92280097 52 _write8(LM75B_REG_CONF, value);
neilt6 0:557a92280097 53 }
neilt6 0:557a92280097 54
neilt6 0:557a92280097 55 LM75B_OS_Mode_t LM75B::getOSMode(void)
neilt6 0:557a92280097 56 {
neilt6 0:557a92280097 57 //Read the 8-bit register value
neilt6 0:557a92280097 58 char value = _read8(LM75B_REG_CONF);
neilt6 0:557a92280097 59
neilt6 0:557a92280097 60 //Return the status of the OS_COMP_INT bit
neilt6 0:557a92280097 61 if (value & (1 << 1))
neilt6 0:557a92280097 62 return LM75B_OS_Interrupt;
neilt6 0:557a92280097 63 else
neilt6 0:557a92280097 64 return LM75B_OS_Comparator;
neilt6 0:557a92280097 65 }
neilt6 0:557a92280097 66
neilt6 0:557a92280097 67 void LM75B::setOSMode(LM75B_OS_Mode_t mode)
neilt6 0:557a92280097 68 {
neilt6 0:557a92280097 69 //Read the current 8-bit register value
neilt6 0:557a92280097 70 char value = _read8(LM75B_REG_CONF);
neilt6 0:557a92280097 71
neilt6 0:557a92280097 72 //Set or clear the OS_COMP_INT bit
neilt6 0:557a92280097 73 if (mode == LM75B_OS_Interrupt)
neilt6 0:557a92280097 74 value |= (1 << 1);
neilt6 0:557a92280097 75 else
neilt6 0:557a92280097 76 value &= ~(1 << 1);
neilt6 0:557a92280097 77
neilt6 0:557a92280097 78 //Write the value back out
neilt6 0:557a92280097 79 _write8(LM75B_REG_CONF, value);
neilt6 0:557a92280097 80 }
neilt6 0:557a92280097 81
neilt6 0:557a92280097 82 LM75B_OS_Polarity_t LM75B::getOSPolarity(void)
neilt6 0:557a92280097 83 {
neilt6 0:557a92280097 84 //Read the 8-bit register value
neilt6 0:557a92280097 85 char value = _read8(LM75B_REG_CONF);
neilt6 0:557a92280097 86
neilt6 0:557a92280097 87 //Return the status of the OS_POL bit
neilt6 0:557a92280097 88 if (value & (1 << 2))
neilt6 0:557a92280097 89 return LM75B_OS_ActiveHigh;
neilt6 0:557a92280097 90 else
neilt6 0:557a92280097 91 return LM75B_OS_ActiveLow;
neilt6 0:557a92280097 92 }
neilt6 0:557a92280097 93
neilt6 0:557a92280097 94 void LM75B::setOSPolarity(LM75B_OS_Polarity_t polarity)
neilt6 0:557a92280097 95 {
neilt6 0:557a92280097 96 //Read the current 8-bit register value
neilt6 0:557a92280097 97 char value = _read8(LM75B_REG_CONF);
neilt6 0:557a92280097 98
neilt6 0:557a92280097 99 //Set or clear the OS_POL bit
neilt6 0:557a92280097 100 if (polarity == LM75B_OS_ActiveHigh)
neilt6 0:557a92280097 101 value |= (1 << 2);
neilt6 0:557a92280097 102 else
neilt6 0:557a92280097 103 value &= ~(1 << 2);
neilt6 0:557a92280097 104
neilt6 0:557a92280097 105 //Write the value back out
neilt6 0:557a92280097 106 _write8(LM75B_REG_CONF, value);
neilt6 0:557a92280097 107 }
neilt6 0:557a92280097 108
neilt6 0:557a92280097 109 LM75B_OS_FaultQueue_t LM75B::getOSFaultQueue(void)
neilt6 0:557a92280097 110 {
neilt6 0:557a92280097 111 //Read the 8-bit register value
neilt6 0:557a92280097 112 char value = _read8(LM75B_REG_CONF);
neilt6 0:557a92280097 113
neilt6 0:557a92280097 114 //Return the status of the OS_F_QUE bits
neilt6 0:557a92280097 115 if ((value & (1 << 3)) && (value & (1 << 4)))
neilt6 0:557a92280097 116 return LM75B_OS_FaultQueue_6;
neilt6 0:557a92280097 117 else if (!(value & (1 << 3)) && (value & (1 << 4)))
neilt6 0:557a92280097 118 return LM75B_OS_FaultQueue_4;
neilt6 0:557a92280097 119 else if ((value & (1 << 3)) && !(value & (1 << 4)))
neilt6 0:557a92280097 120 return LM75B_OS_FaultQueue_2;
neilt6 0:557a92280097 121 else
neilt6 0:557a92280097 122 return LM75B_OS_FaultQueue_1;
neilt6 0:557a92280097 123 }
neilt6 0:557a92280097 124
neilt6 0:557a92280097 125 void LM75B::setOSFaultQueue(LM75B_OS_FaultQueue_t queue)
neilt6 0:557a92280097 126 {
neilt6 0:557a92280097 127 //Read the current 8-bit register value
neilt6 0:557a92280097 128 char value = _read8(LM75B_REG_CONF);
neilt6 0:557a92280097 129
neilt6 0:557a92280097 130 //Clear the old OS_F_QUE bits
neilt6 0:557a92280097 131 value &= ~(3 << 3);
neilt6 0:557a92280097 132
neilt6 0:557a92280097 133 //Set the new OS_F_QUE bits
neilt6 0:557a92280097 134 if (queue == LM75B_OS_FaultQueue_2)
neilt6 0:557a92280097 135 value |= (1 << 3);
neilt6 0:557a92280097 136 else if (queue == LM75B_OS_FaultQueue_4)
neilt6 0:557a92280097 137 value |= (2 << 3);
neilt6 0:557a92280097 138 else if (queue == LM75B_OS_FaultQueue_6)
neilt6 0:557a92280097 139 value |= (3 << 3);
neilt6 0:557a92280097 140
neilt6 0:557a92280097 141 //Write the value back out
neilt6 0:557a92280097 142 _write8(LM75B_REG_CONF, value);
neilt6 0:557a92280097 143 }
neilt6 0:557a92280097 144
neilt6 0:557a92280097 145 float LM75B::getAlertTemp(void)
neilt6 0:557a92280097 146 {
neilt6 0:557a92280097 147 //Use the 9-bit helper to read the TOS register
neilt6 0:557a92280097 148 return _readTempHelper(LM75B_REG_TOS);
neilt6 0:557a92280097 149 }
neilt6 0:557a92280097 150
neilt6 0:557a92280097 151 void LM75B::setAlertTemp(float temp)
neilt6 0:557a92280097 152 {
neilt6 0:557a92280097 153 //Use the 9-bit helper to write to the TOS register
neilt6 0:557a92280097 154 return _writeTempHelper(LM75B_REG_TOS, temp);
neilt6 0:557a92280097 155 }
neilt6 0:557a92280097 156
neilt6 0:557a92280097 157 float LM75B::getAlertHyst(void)
neilt6 0:557a92280097 158 {
neilt6 0:557a92280097 159 //Use the 9-bit helper to read the THYST register
neilt6 0:557a92280097 160 return _readTempHelper(LM75B_REG_THYST);
neilt6 0:557a92280097 161 }
neilt6 0:557a92280097 162
neilt6 0:557a92280097 163 void LM75B::setAlertHyst(float temp)
neilt6 0:557a92280097 164 {
neilt6 0:557a92280097 165 //Use the 9-bit helper to write to the THYST register
neilt6 0:557a92280097 166 return _writeTempHelper(LM75B_REG_THYST, temp);
neilt6 0:557a92280097 167 }
neilt6 0:557a92280097 168
neilt6 0:557a92280097 169 float LM75B::getTemp(void)
neilt6 0:557a92280097 170 {
neilt6 0:557a92280097 171 //Signed return value
neilt6 0:557a92280097 172 short value;
neilt6 0:557a92280097 173
neilt6 0:557a92280097 174 //Read the 11-bit raw temperature value
neilt6 0:557a92280097 175 value = _read16(LM75B_REG_TEMP) >> 5;
neilt6 0:557a92280097 176
neilt6 0:557a92280097 177 //Sign extend negative numbers
neilt6 0:557a92280097 178 if (value & (1 << 10))
neilt6 0:557a92280097 179 value |= 0xFC00;
neilt6 0:557a92280097 180
neilt6 0:557a92280097 181 //Return the temperature in °C
neilt6 0:557a92280097 182 return value * 0.125;
neilt6 0:557a92280097 183 }
neilt6 0:557a92280097 184
neilt6 0:557a92280097 185 char LM75B::_read8(char reg)
neilt6 0:557a92280097 186 {
neilt6 0:557a92280097 187 //Select the register
neilt6 0:557a92280097 188 _i2c.write(_addr, &reg, 1);
neilt6 0:557a92280097 189
neilt6 0:557a92280097 190 //Read the 8-bit register
neilt6 0:557a92280097 191 _i2c.read(_addr, &reg, 1);
neilt6 0:557a92280097 192
neilt6 0:557a92280097 193 //Return the byte
neilt6 0:557a92280097 194 return reg;
neilt6 0:557a92280097 195 }
neilt6 0:557a92280097 196
neilt6 0:557a92280097 197 void LM75B::_write8(char reg, char data)
neilt6 0:557a92280097 198 {
neilt6 0:557a92280097 199 //Create a temporary buffer
neilt6 0:557a92280097 200 char buff[2];
neilt6 0:557a92280097 201
neilt6 0:557a92280097 202 //Load the register address and 8-bit data
neilt6 0:557a92280097 203 buff[0] = reg;
neilt6 0:557a92280097 204 buff[1] = data;
neilt6 0:557a92280097 205
neilt6 0:557a92280097 206 //Write the data
neilt6 0:557a92280097 207 _i2c.write(_addr, buff, 2);
neilt6 0:557a92280097 208 }
neilt6 0:557a92280097 209
neilt6 0:557a92280097 210 unsigned short LM75B::_read16(char reg)
neilt6 0:557a92280097 211 {
neilt6 0:557a92280097 212 //Create a temporary buffer
neilt6 0:557a92280097 213 char buff[2];
neilt6 0:557a92280097 214
neilt6 0:557a92280097 215 //Select the register
neilt6 0:557a92280097 216 _i2c.write(_addr, &reg, 1);
neilt6 0:557a92280097 217
neilt6 0:557a92280097 218 //Read the 16-bit register
neilt6 0:557a92280097 219 _i2c.read(_addr, buff, 2);
neilt6 0:557a92280097 220
neilt6 0:557a92280097 221 //Return the combined 16-bit value
neilt6 0:557a92280097 222 return (buff[0] << 8) | buff[1];
neilt6 0:557a92280097 223 }
neilt6 0:557a92280097 224
neilt6 0:557a92280097 225 void LM75B::_write16(char reg, unsigned short data)
neilt6 0:557a92280097 226 {
neilt6 0:557a92280097 227 //Create a temporary buffer
neilt6 0:557a92280097 228 char buff[3];
neilt6 0:557a92280097 229
neilt6 0:557a92280097 230 //Load the register address and 16-bit data
neilt6 0:557a92280097 231 buff[0] = reg;
neilt6 0:557a92280097 232 buff[1] = data >> 8;
neilt6 0:557a92280097 233 buff[2] = data;
neilt6 0:557a92280097 234
neilt6 0:557a92280097 235 //Write the data
neilt6 0:557a92280097 236 _i2c.write(_addr, buff, 3);
neilt6 0:557a92280097 237 }
neilt6 0:557a92280097 238
neilt6 0:557a92280097 239 float LM75B::_readTempHelper(char reg)
neilt6 0:557a92280097 240 {
neilt6 0:557a92280097 241 //Signed return value
neilt6 0:557a92280097 242 short value;
neilt6 0:557a92280097 243
neilt6 0:557a92280097 244 //Read the 9-bit raw temperature value
neilt6 0:557a92280097 245 value = _read16(reg) >> 7;
neilt6 0:557a92280097 246
neilt6 0:557a92280097 247 //Sign extend negative numbers
neilt6 0:557a92280097 248 if (value & (1 << 8))
neilt6 0:557a92280097 249 value |= 0xFF00;
neilt6 0:557a92280097 250
neilt6 0:557a92280097 251 //Return the temperature in °C
neilt6 0:557a92280097 252 return value * 0.5;
neilt6 0:557a92280097 253 }
neilt6 0:557a92280097 254
neilt6 0:557a92280097 255 void LM75B::_writeTempHelper(char reg, float temp)
neilt6 0:557a92280097 256 {
neilt6 0:557a92280097 257 //Range limit temp
neilt6 0:557a92280097 258 if (temp < -55.0)
neilt6 0:557a92280097 259 temp = -55.0;
neilt6 0:557a92280097 260 else if (temp > 125.0)
neilt6 0:557a92280097 261 temp = 125.0;
neilt6 0:557a92280097 262
neilt6 0:557a92280097 263 //Extract and shift the signed integer
neilt6 0:557a92280097 264 short value = temp * 2;
neilt6 0:557a92280097 265 value <<= 7;
neilt6 0:557a92280097 266
neilt6 0:557a92280097 267 //Send the new value
neilt6 0:557a92280097 268 _write16(reg, value);
neilt6 0:557a92280097 269 }