Neil Thiessen / LM75B

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

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

LM75B.cpp@4:06676376766a, 2013-08-02 (annotated)

Committer:
neilt6
Date:
Fri Aug 02 22:00:15 2013 +0000
Revision:
4:06676376766a
Parent:
3:9d68eed28bfb
Child:
8:2b797c309258
Fixed Apache 2.0 license headers

Who changed what in which revision?

UserRevisionLine numberNew contents of line
neilt6 2:9ecc39b2ca70 1 /* LM75B Driver Library
neilt6 4:06676376766a 2 * Copyright (c) 2013 Neil Thiessen
neilt6 0:557a92280097 3 *
neilt6 3:9d68eed28bfb 4 * Licensed under the Apache License, Version 2.0 (the "License");
neilt6 3:9d68eed28bfb 5 * you may not use this file except in compliance with the License.
neilt6 3:9d68eed28bfb 6 * You may obtain a copy of the License at
neilt6 4:06676376766a 7 *
neilt6 4:06676376766a 8 * http://www.apache.org/licenses/LICENSE-2.0
neilt6 0:557a92280097 9 *
neilt6 3:9d68eed28bfb 10 * Unless required by applicable law or agreed to in writing, software
neilt6 3:9d68eed28bfb 11 * distributed under the License is distributed on an "AS IS" BASIS,
neilt6 3:9d68eed28bfb 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
neilt6 3:9d68eed28bfb 13 * See the License for the specific language governing permissions and
neilt6 3:9d68eed28bfb 14 * limitations under the License.
neilt6 0:557a92280097 15 */
neilt6 0:557a92280097 16
neilt6 0:557a92280097 17 #include "LM75B.h"
neilt6 0:557a92280097 18 #include "mbed.h"
neilt6 0:557a92280097 19
neilt6 2:9ecc39b2ca70 20 LM75B::LM75B(PinName sda, PinName scl, Address addr) : _i2c(sda, scl)
neilt6 0:557a92280097 21 {
neilt6 0:557a92280097 22 //Set the internal device address
neilt6 2:9ecc39b2ca70 23 _addr = (int)addr;
neilt6 0:557a92280097 24 }
neilt6 0:557a92280097 25
neilt6 2:9ecc39b2ca70 26 LM75B::PowerMode LM75B::getPowerMode(void)
neilt6 0:557a92280097 27 {
neilt6 0:557a92280097 28 //Read the 8-bit register value
neilt6 2:9ecc39b2ca70 29 char value = _read8(__LM75B_REG_CONF);
neilt6 0:557a92280097 30
neilt6 0:557a92280097 31 //Return the status of the SHUTDOWN bit
neilt6 0:557a92280097 32 if (value & (1 << 0))
neilt6 2:9ecc39b2ca70 33 return POWER_SHUTDOWN;
neilt6 0:557a92280097 34 else
neilt6 2:9ecc39b2ca70 35 return POWER_NORMAL;
neilt6 0:557a92280097 36 }
neilt6 0:557a92280097 37
neilt6 2:9ecc39b2ca70 38 void LM75B::setPowerMode(PowerMode mode)
neilt6 0:557a92280097 39 {
neilt6 0:557a92280097 40 //Read the current 8-bit register value
neilt6 2:9ecc39b2ca70 41 char value = _read8(__LM75B_REG_CONF);
neilt6 0:557a92280097 42
neilt6 0:557a92280097 43 //Set or clear the SHUTDOWN bit
neilt6 2:9ecc39b2ca70 44 if (mode == POWER_SHUTDOWN)
neilt6 0:557a92280097 45 value |= (1 << 0);
neilt6 0:557a92280097 46 else
neilt6 0:557a92280097 47 value &= ~(1 << 0);
neilt6 0:557a92280097 48
neilt6 0:557a92280097 49 //Write the value back out
neilt6 2:9ecc39b2ca70 50 _write8(__LM75B_REG_CONF, value);
neilt6 0:557a92280097 51 }
neilt6 0:557a92280097 52
neilt6 2:9ecc39b2ca70 53 LM75B::OSMode LM75B::getOSMode(void)
neilt6 0:557a92280097 54 {
neilt6 0:557a92280097 55 //Read the 8-bit register value
neilt6 2:9ecc39b2ca70 56 char value = _read8(__LM75B_REG_CONF);
neilt6 0:557a92280097 57
neilt6 0:557a92280097 58 //Return the status of the OS_COMP_INT bit
neilt6 0:557a92280097 59 if (value & (1 << 1))
neilt6 2:9ecc39b2ca70 60 return OS_INTERRUPT;
neilt6 0:557a92280097 61 else
neilt6 2:9ecc39b2ca70 62 return OS_COMPARATOR;
neilt6 0:557a92280097 63 }
neilt6 0:557a92280097 64
neilt6 2:9ecc39b2ca70 65 void LM75B::setOSMode(OSMode mode)
neilt6 0:557a92280097 66 {
neilt6 0:557a92280097 67 //Read the current 8-bit register value
neilt6 2:9ecc39b2ca70 68 char value = _read8(__LM75B_REG_CONF);
neilt6 0:557a92280097 69
neilt6 0:557a92280097 70 //Set or clear the OS_COMP_INT bit
neilt6 2:9ecc39b2ca70 71 if (mode == OS_INTERRUPT)
neilt6 0:557a92280097 72 value |= (1 << 1);
neilt6 0:557a92280097 73 else
neilt6 0:557a92280097 74 value &= ~(1 << 1);
neilt6 0:557a92280097 75
neilt6 0:557a92280097 76 //Write the value back out
neilt6 2:9ecc39b2ca70 77 _write8(__LM75B_REG_CONF, value);
neilt6 0:557a92280097 78 }
neilt6 0:557a92280097 79
neilt6 2:9ecc39b2ca70 80 LM75B::OSPolarity LM75B::getOSPolarity(void)
neilt6 0:557a92280097 81 {
neilt6 0:557a92280097 82 //Read the 8-bit register value
neilt6 2:9ecc39b2ca70 83 char value = _read8(__LM75B_REG_CONF);
neilt6 0:557a92280097 84
neilt6 0:557a92280097 85 //Return the status of the OS_POL bit
neilt6 0:557a92280097 86 if (value & (1 << 2))
neilt6 2:9ecc39b2ca70 87 return OS_ACTIVE_HIGH;
neilt6 0:557a92280097 88 else
neilt6 2:9ecc39b2ca70 89 return OS_ACTIVE_LOW;
neilt6 0:557a92280097 90 }
neilt6 0:557a92280097 91
neilt6 2:9ecc39b2ca70 92 void LM75B::setOSPolarity(OSPolarity polarity)
neilt6 0:557a92280097 93 {
neilt6 0:557a92280097 94 //Read the current 8-bit register value
neilt6 2:9ecc39b2ca70 95 char value = _read8(__LM75B_REG_CONF);
neilt6 0:557a92280097 96
neilt6 0:557a92280097 97 //Set or clear the OS_POL bit
neilt6 2:9ecc39b2ca70 98 if (polarity == OS_ACTIVE_HIGH)
neilt6 0:557a92280097 99 value |= (1 << 2);
neilt6 0:557a92280097 100 else
neilt6 0:557a92280097 101 value &= ~(1 << 2);
neilt6 0:557a92280097 102
neilt6 0:557a92280097 103 //Write the value back out
neilt6 2:9ecc39b2ca70 104 _write8(__LM75B_REG_CONF, value);
neilt6 0:557a92280097 105 }
neilt6 0:557a92280097 106
neilt6 2:9ecc39b2ca70 107 LM75B::OSFaultQueue LM75B::getOSFaultQueue(void)
neilt6 0:557a92280097 108 {
neilt6 0:557a92280097 109 //Read the 8-bit register value
neilt6 2:9ecc39b2ca70 110 char value = _read8(__LM75B_REG_CONF);
neilt6 0:557a92280097 111
neilt6 0:557a92280097 112 //Return the status of the OS_F_QUE bits
neilt6 0:557a92280097 113 if ((value & (1 << 3)) && (value & (1 << 4)))
neilt6 2:9ecc39b2ca70 114 return OS_FAULT_QUEUE_6;
neilt6 0:557a92280097 115 else if (!(value & (1 << 3)) && (value & (1 << 4)))
neilt6 2:9ecc39b2ca70 116 return OS_FAULT_QUEUE_4;
neilt6 0:557a92280097 117 else if ((value & (1 << 3)) && !(value & (1 << 4)))
neilt6 2:9ecc39b2ca70 118 return OS_FAULT_QUEUE_2;
neilt6 0:557a92280097 119 else
neilt6 2:9ecc39b2ca70 120 return OS_FAULT_QUEUE_1;
neilt6 0:557a92280097 121 }
neilt6 0:557a92280097 122
neilt6 2:9ecc39b2ca70 123 void LM75B::setOSFaultQueue(OSFaultQueue queue)
neilt6 0:557a92280097 124 {
neilt6 0:557a92280097 125 //Read the current 8-bit register value
neilt6 2:9ecc39b2ca70 126 char value = _read8(__LM75B_REG_CONF);
neilt6 0:557a92280097 127
neilt6 0:557a92280097 128 //Clear the old OS_F_QUE bits
neilt6 0:557a92280097 129 value &= ~(3 << 3);
neilt6 0:557a92280097 130
neilt6 0:557a92280097 131 //Set the new OS_F_QUE bits
neilt6 2:9ecc39b2ca70 132 if (queue == OS_FAULT_QUEUE_2)
neilt6 0:557a92280097 133 value |= (1 << 3);
neilt6 2:9ecc39b2ca70 134 else if (queue == OS_FAULT_QUEUE_4)
neilt6 0:557a92280097 135 value |= (2 << 3);
neilt6 2:9ecc39b2ca70 136 else if (queue == OS_FAULT_QUEUE_6)
neilt6 0:557a92280097 137 value |= (3 << 3);
neilt6 0:557a92280097 138
neilt6 0:557a92280097 139 //Write the value back out
neilt6 2:9ecc39b2ca70 140 _write8(__LM75B_REG_CONF, value);
neilt6 0:557a92280097 141 }
neilt6 0:557a92280097 142
neilt6 0:557a92280097 143 float LM75B::getAlertTemp(void)
neilt6 0:557a92280097 144 {
neilt6 0:557a92280097 145 //Use the 9-bit helper to read the TOS register
neilt6 2:9ecc39b2ca70 146 return _readTempHelper(__LM75B_REG_TOS);
neilt6 0:557a92280097 147 }
neilt6 0:557a92280097 148
neilt6 0:557a92280097 149 void LM75B::setAlertTemp(float temp)
neilt6 0:557a92280097 150 {
neilt6 0:557a92280097 151 //Use the 9-bit helper to write to the TOS register
neilt6 2:9ecc39b2ca70 152 return _writeTempHelper(__LM75B_REG_TOS, temp);
neilt6 0:557a92280097 153 }
neilt6 0:557a92280097 154
neilt6 0:557a92280097 155 float LM75B::getAlertHyst(void)
neilt6 0:557a92280097 156 {
neilt6 0:557a92280097 157 //Use the 9-bit helper to read the THYST register
neilt6 2:9ecc39b2ca70 158 return _readTempHelper(__LM75B_REG_THYST);
neilt6 0:557a92280097 159 }
neilt6 0:557a92280097 160
neilt6 0:557a92280097 161 void LM75B::setAlertHyst(float temp)
neilt6 0:557a92280097 162 {
neilt6 0:557a92280097 163 //Use the 9-bit helper to write to the THYST register
neilt6 2:9ecc39b2ca70 164 return _writeTempHelper(__LM75B_REG_THYST, temp);
neilt6 0:557a92280097 165 }
neilt6 0:557a92280097 166
neilt6 0:557a92280097 167 float LM75B::getTemp(void)
neilt6 0:557a92280097 168 {
neilt6 0:557a92280097 169 //Signed return value
neilt6 0:557a92280097 170 short value;
neilt6 0:557a92280097 171
neilt6 0:557a92280097 172 //Read the 11-bit raw temperature value
neilt6 2:9ecc39b2ca70 173 value = _read16(__LM75B_REG_TEMP) >> 5;
neilt6 0:557a92280097 174
neilt6 0:557a92280097 175 //Sign extend negative numbers
neilt6 0:557a92280097 176 if (value & (1 << 10))
neilt6 0:557a92280097 177 value |= 0xFC00;
neilt6 0:557a92280097 178
neilt6 0:557a92280097 179 //Return the temperature in °C
neilt6 0:557a92280097 180 return value * 0.125;
neilt6 0:557a92280097 181 }
neilt6 0:557a92280097 182
neilt6 0:557a92280097 183 char LM75B::_read8(char reg)
neilt6 0:557a92280097 184 {
neilt6 0:557a92280097 185 //Select the register
neilt6 0:557a92280097 186 _i2c.write(_addr, &reg, 1);
neilt6 0:557a92280097 187
neilt6 0:557a92280097 188 //Read the 8-bit register
neilt6 0:557a92280097 189 _i2c.read(_addr, &reg, 1);
neilt6 0:557a92280097 190
neilt6 0:557a92280097 191 //Return the byte
neilt6 0:557a92280097 192 return reg;
neilt6 0:557a92280097 193 }
neilt6 0:557a92280097 194
neilt6 0:557a92280097 195 void LM75B::_write8(char reg, char data)
neilt6 0:557a92280097 196 {
neilt6 0:557a92280097 197 //Create a temporary buffer
neilt6 0:557a92280097 198 char buff[2];
neilt6 0:557a92280097 199
neilt6 0:557a92280097 200 //Load the register address and 8-bit data
neilt6 0:557a92280097 201 buff[0] = reg;
neilt6 0:557a92280097 202 buff[1] = data;
neilt6 0:557a92280097 203
neilt6 0:557a92280097 204 //Write the data
neilt6 0:557a92280097 205 _i2c.write(_addr, buff, 2);
neilt6 0:557a92280097 206 }
neilt6 0:557a92280097 207
neilt6 0:557a92280097 208 unsigned short LM75B::_read16(char reg)
neilt6 0:557a92280097 209 {
neilt6 0:557a92280097 210 //Create a temporary buffer
neilt6 0:557a92280097 211 char buff[2];
neilt6 0:557a92280097 212
neilt6 0:557a92280097 213 //Select the register
neilt6 0:557a92280097 214 _i2c.write(_addr, &reg, 1);
neilt6 0:557a92280097 215
neilt6 0:557a92280097 216 //Read the 16-bit register
neilt6 0:557a92280097 217 _i2c.read(_addr, buff, 2);
neilt6 0:557a92280097 218
neilt6 0:557a92280097 219 //Return the combined 16-bit value
neilt6 0:557a92280097 220 return (buff[0] << 8) | buff[1];
neilt6 0:557a92280097 221 }
neilt6 0:557a92280097 222
neilt6 0:557a92280097 223 void LM75B::_write16(char reg, unsigned short data)
neilt6 0:557a92280097 224 {
neilt6 0:557a92280097 225 //Create a temporary buffer
neilt6 0:557a92280097 226 char buff[3];
neilt6 0:557a92280097 227
neilt6 0:557a92280097 228 //Load the register address and 16-bit data
neilt6 0:557a92280097 229 buff[0] = reg;
neilt6 0:557a92280097 230 buff[1] = data >> 8;
neilt6 0:557a92280097 231 buff[2] = data;
neilt6 0:557a92280097 232
neilt6 0:557a92280097 233 //Write the data
neilt6 0:557a92280097 234 _i2c.write(_addr, buff, 3);
neilt6 0:557a92280097 235 }
neilt6 0:557a92280097 236
neilt6 0:557a92280097 237 float LM75B::_readTempHelper(char reg)
neilt6 0:557a92280097 238 {
neilt6 0:557a92280097 239 //Signed return value
neilt6 0:557a92280097 240 short value;
neilt6 0:557a92280097 241
neilt6 0:557a92280097 242 //Read the 9-bit raw temperature value
neilt6 0:557a92280097 243 value = _read16(reg) >> 7;
neilt6 0:557a92280097 244
neilt6 0:557a92280097 245 //Sign extend negative numbers
neilt6 0:557a92280097 246 if (value & (1 << 8))
neilt6 0:557a92280097 247 value |= 0xFF00;
neilt6 0:557a92280097 248
neilt6 0:557a92280097 249 //Return the temperature in °C
neilt6 0:557a92280097 250 return value * 0.5;
neilt6 0:557a92280097 251 }
neilt6 0:557a92280097 252
neilt6 0:557a92280097 253 void LM75B::_writeTempHelper(char reg, float temp)
neilt6 0:557a92280097 254 {
neilt6 0:557a92280097 255 //Range limit temp
neilt6 0:557a92280097 256 if (temp < -55.0)
neilt6 0:557a92280097 257 temp = -55.0;
neilt6 0:557a92280097 258 else if (temp > 125.0)
neilt6 0:557a92280097 259 temp = 125.0;
neilt6 0:557a92280097 260
neilt6 0:557a92280097 261 //Extract and shift the signed integer
neilt6 0:557a92280097 262 short value = temp * 2;
neilt6 0:557a92280097 263 value <<= 7;
neilt6 0:557a92280097 264
neilt6 0:557a92280097 265 //Send the new value
neilt6 0:557a92280097 266 _write16(reg, value);
neilt6 0:557a92280097 267 }