Lucian Corduneanu / DS1820

Dallas' DS1820 family temperature sensor using mbed debug logs.

Dependencies:   OneWire

Fork of DS1820 by Zoltan Hudak

DS1820.cpp@17:325cd3a6cbbb, 2018-05-02 (annotated)

Committer:
Lucian Corduneanu
Date:
Wed May 02 14:18:08 2018 +0300
Revision:
17:325cd3a6cbbb
Parent:
16:0764e4de41d2 
Remove OneWire dependency

Who changed what in which revision?

UserRevisionLine numberNew contents of line
hudakz 3:a250babd0a9f 1 /*
hudakz 3:a250babd0a9f 2 * Dallas' DS1820 family temperature sensor.
hudakz 3:a250babd0a9f 3 * This library depends on the OneWire library (Dallas' 1-Wire bus protocol implementation)
hudakz 6:518950e436be 4 * available at <http://developer.mbed.org/users/hudakz/code/OneWire/>
hudakz 3:a250babd0a9f 5 *
hudakz 3:a250babd0a9f 6 * Example of use:
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 7
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 8 #include "mbed.h"
hudakz 0:433af64321d5 9 #include "DS1820.h"
hudakz 0:433af64321d5 10
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 11 Serial serial(USBTX, USBRX);
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 12
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 13 int main() {
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 14 serial.baud(115200);
lucian@Lucians-MacBook-Pro.local 15:8b82d53770df 15 DS1820 ds1820(PB_2); // substitute PB_2 with actual mbed pin name connected to the DS1820 data pin.
hudakz 0:433af64321d5 16
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 17 if(ds1820.begin()) {
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 18 ds1820.startConversion(); // start temperature conversion
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 19 wait(2.0); // let DS1820 complete the temperature conversion
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 20 while(1) {
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 21 float temp = 0.0;
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 22 ds1820.read(temp);
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 23 serial.printf("temp = %3.1f\r\n", temp); // read temperature
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 24 ds1820.startConversion(); // start temperature conversion
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 25 wait(1.0); // let DS1820 complete the temperature conversion
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 26 }
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 27 } else
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 28 serial.printf("No DS1820 sensor found!\r\n");
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 29 }
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 30
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 31 */
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 32
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 33 #include "DS1820.h"
hudakz 0:433af64321d5 34
hudakz 0:433af64321d5 35 /**
hudakz 0:433af64321d5 36 * @brief Constructs a generic DS1820 sensor
hudakz 0:433af64321d5 37 * @note begin() must be called to detect and initialize the actual model
hudakz 3:a250babd0a9f 38 * @param pin: Name of data pin
hudakz 0:433af64321d5 39 * @retval
hudakz 0:433af64321d5 40 */
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 41 DS1820::DS1820(PinName pin) : oneWire(pin) {
hudakz 8:8dfdd1603e4d 42 present = false;
hudakz 8:8dfdd1603e4d 43 model_s = false;
hudakz 0:433af64321d5 44 }
hudakz 0:433af64321d5 45
hudakz 0:433af64321d5 46 /**
hudakz 0:433af64321d5 47 * @brief Constructs a specific model
hudakz 0:433af64321d5 48 * @note No need to call begin() to detect and initialize the model
hudakz 3:a250babd0a9f 49 * @param model: One character model name: 'S', 's', 'B' or 'b'
hudakz 3:a250babd0a9f 50 * pin: Name of data pin
hudakz 0:433af64321d5 51 * @retval
hudakz 0:433af64321d5 52 */
hudakz 0:433af64321d5 53 DS1820::DS1820(char model, PinName pin) :
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 54 oneWire(pin) {
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 55 if ((model == 'S') or (model == 's')) {
hudakz 8:8dfdd1603e4d 56 present = true;
hudakz 8:8dfdd1603e4d 57 model_s = true;
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 58 } else if ((model == 'B') or (model == 'b')) {
hudakz 8:8dfdd1603e4d 59 present = true;
hudakz 8:8dfdd1603e4d 60 model_s = false;
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 61 } else
hudakz 8:8dfdd1603e4d 62 present = false;
hudakz 0:433af64321d5 63 }
hudakz 0:433af64321d5 64
hudakz 0:433af64321d5 65 /**
hudakz 0:433af64321d5 66 * @brief Detects and initializes the actual DS1820 model
hudakz 0:433af64321d5 67 * @note
hudakz 0:433af64321d5 68 * @param
hudakz 0:433af64321d5 69 * @retval true: if a DS1820 family sensor was detected and initialized
hudakz 0:433af64321d5 70 false: otherwise
hudakz 0:433af64321d5 71 */
hudakz 0:433af64321d5 72 bool DS1820::begin(void) {
hudakz 0:433af64321d5 73 oneWire.reset_search();
hudakz 0:433af64321d5 74 wait_ms(250);
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 75 if (!oneWire.search(addr)) {
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 76 debug_if(DEBUG, "No addresses.\r\n");
hudakz 0:433af64321d5 77 oneWire.reset_search();
hudakz 0:433af64321d5 78 wait_ms(250);
hudakz 0:433af64321d5 79 return false;
hudakz 0:433af64321d5 80 }
hudakz 0:433af64321d5 81
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 82 debug_if(DEBUG, "ROM =");
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 83 for (uint8_t i = 0; i < 8; i++) {
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 84 debug_if(DEBUG, " %x", addr[i]);
hudakz 0:433af64321d5 85 }
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 86 debug_if(DEBUG, "\r\n");
hudakz 0:433af64321d5 87
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 88 if (OneWire::crc8(addr, 7) == addr[7]) {
hudakz 8:8dfdd1603e4d 89 present = true;
hudakz 0:433af64321d5 90
hudakz 0:433af64321d5 91 // the first ROM byte indicates which chip
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 92 switch (addr[0]) {
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 93 case 0x10:
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 94 model_s = true;
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 95 debug_if(DEBUG, "DS18S20 or old DS1820\r\n");
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 96 break;
hudakz 0:433af64321d5 97
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 98 case 0x28:
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 99 model_s = false;
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 100 debug_if(DEBUG, "DS18B20\r\n");
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 101 break;
hudakz 0:433af64321d5 102
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 103 case 0x22:
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 104 model_s = false;
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 105 debug_if(DEBUG, "DS1822\r\n");
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 106 break;
hudakz 0:433af64321d5 107
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 108 default:
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 109 present = false;
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 110 debug_if(DEBUG, "Device doesn't belong to the DS1820 family\r\n");
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 111 return false;
hudakz 0:433af64321d5 112 }
hudakz 0:433af64321d5 113 return true;
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 114 } else {
hudakz 0:433af64321d5 115 return false;
hudakz 0:433af64321d5 116 }
hudakz 0:433af64321d5 117 }
hudakz 0:433af64321d5 118
hudakz 0:433af64321d5 119 /**
hudakz 8:8dfdd1603e4d 120 * @brief Informs about presence of a DS1820 sensor.
hudakz 8:8dfdd1603e4d 121 * @note begin() shall be called before using this function
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 122 * if a generic DS1820 instance was created by the user.
hudakz 8:8dfdd1603e4d 123 * No need to call begin() for a specific DS1820 instance.
hudakz 8:8dfdd1603e4d 124 * @param
hudakz 8:8dfdd1603e4d 125 * @retval true: when a DS1820 sensor is present
hudakz 8:8dfdd1603e4d 126 * false: otherwise
hudakz 8:8dfdd1603e4d 127 */
hudakz 8:8dfdd1603e4d 128 bool DS1820::isPresent(void) {
hudakz 8:8dfdd1603e4d 129 return present;
hudakz 8:8dfdd1603e4d 130 }
hudakz 8:8dfdd1603e4d 131
hudakz 8:8dfdd1603e4d 132 /**
hudakz 6:518950e436be 133 * @brief Sets temperature-to-digital conversion resolution.
hudakz 4:adf4e7972d73 134 * @note The configuration register allows the user to set the resolution
hudakz 6:518950e436be 135 * of the temperature-to-digital conversion to 9, 10, 11, or 12 bits.
hudakz 6:518950e436be 136 * Defaults to 12-bit resolution for DS18B20.
hudakz 6:518950e436be 137 * DS18S20 allows only 9-bit resolution.
hudakz 6:518950e436be 138 * @param res: Resolution of the temperature-to-digital conversion in bits.
hudakz 4:adf4e7972d73 139 * @retval
hudakz 4:adf4e7972d73 140 */
hudakz 4:adf4e7972d73 141 void DS1820::setResolution(uint8_t res) {
hudakz 4:adf4e7972d73 142 // keep resolution within limits
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 143 if (res > 12)
hudakz 4:adf4e7972d73 144 res = 12;
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 145 if (res < 9)
hudakz 4:adf4e7972d73 146 res = 9;
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 147 if (model_s)
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 148 res = 9;
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 149
hudakz 4:adf4e7972d73 150 oneWire.reset();
hudakz 4:adf4e7972d73 151 oneWire.skip();
hudakz 4:adf4e7972d73 152 oneWire.write(0xBE); // to read Scratchpad
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 153 for (uint8_t i = 0; i < 9; i++) // read Scratchpad bytes
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 154 data[i] = oneWire.read();
hudakz 4:adf4e7972d73 155
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 156 data[4] |= (res - 9) << 5; // update configuration byte (set resolution)
hudakz 4:adf4e7972d73 157 oneWire.reset();
hudakz 4:adf4e7972d73 158 oneWire.skip();
hudakz 4:adf4e7972d73 159 oneWire.write(0x4E); // to write into Scratchpad
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 160 for (uint8_t i = 2; i < 5; i++) // write three bytes (2nd, 3rd, 4th) into Scratchpad
hudakz 4:adf4e7972d73 161 oneWire.write(data[i]);
hudakz 4:adf4e7972d73 162 }
hudakz 4:adf4e7972d73 163
hudakz 4:adf4e7972d73 164 /**
hudakz 0:433af64321d5 165 * @brief Starts temperature conversion
hudakz 6:518950e436be 166 * @note The time to complete the converion depends on the selected resolution:
hudakz 6:518950e436be 167 * 9-bit resolution -> max conversion time = 93.75ms
hudakz 6:518950e436be 168 * 10-bit resolution -> max conversion time = 187.5ms
hudakz 6:518950e436be 169 * 11-bit resolution -> max conversion time = 375ms
hudakz 6:518950e436be 170 * 12-bit resolution -> max conversion time = 750ms
hudakz 0:433af64321d5 171 * @param
hudakz 0:433af64321d5 172 * @retval
hudakz 0:433af64321d5 173 */
hudakz 0:433af64321d5 174 void DS1820::startConversion(void) {
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 175 if (present) {
hudakz 0:433af64321d5 176 oneWire.reset();
hudakz 0:433af64321d5 177 oneWire.skip();
hudakz 3:a250babd0a9f 178 oneWire.write(0x44); //start temperature conversion
hudakz 0:433af64321d5 179 }
hudakz 0:433af64321d5 180 }
hudakz 0:433af64321d5 181
hudakz 0:433af64321d5 182 /**
hudakz 13:b593a82ce790 183 * @brief Reads temperature from chip's scratchpad.
hudakz 13:b593a82ce790 184 * @note Verifies data integrity by calculating cyclic redundancy check (CRC).
hudakz 13:b593a82ce790 185 * If the calculated CRC dosn't match the one stored in chip's scratchpad register
hudakz 13:b593a82ce790 186 * the temperature variable is not updated and CRC error code is returned.
hudakz 13:b593a82ce790 187 * @param temp: The temperature variable to be updated by this routine.
hudakz 13:b593a82ce790 188 * (It's passed as reference to floating point.)
hudakz 13:b593a82ce790 189 * @retval error code:
hudakz 13:b593a82ce790 190 * 0 - no errors ('temp' contains the temperature measured)
hudakz 13:b593a82ce790 191 * 1 - sensor not present ('temp' is not updated)
hudakz 13:b593a82ce790 192 * 2 - CRC error ('temp' is not updated)
hudakz 13:b593a82ce790 193 */
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 194 uint8_t DS1820::read(float &temp) {
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 195 uint16_t temp_uint16 = 0;
lucian@Lucians-MacBook-Pro.local 16:0764e4de41d2 196 uint8_t result = readRaw(temp_uint16);
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 197 bool temp_available = 0 == result;
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 198
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 199 if (temp_available) {
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 200 debug_if(DEBUG, "raw uint16 = 0x%02X \r\n", temp_uint16);
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 201 // Convert to floating point value
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 202 temp = toFloat(temp_uint16);
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 203 }
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 204 }
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 205
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 206 /**
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 207 * @brief Reads temperature from chip's scratchpad.
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 208 * @note Verifies data integrity by calculating cyclic redundancy check (CRC).
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 209 * If the calculated CRC dosn't match the one stored in chip's scratchpad register
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 210 * the temperature variable is not updated and CRC error code is returned.
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 211 * @param temp: The temperature variable to be updated by this routine.
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 212 * (It's passed as reference to uint16_t)
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 213 * @retval error code:
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 214 * 0 - no errors ('temp' contains the temperature measured)
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 215 * 1 - sensor not present ('temp' is not updated)
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 216 * 2 - CRC error ('temp' is not updated)
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 217 */
lucian@Lucians-MacBook-Pro.local 16:0764e4de41d2 218 uint8_t DS1820::readRaw(uint16_t &temp) {
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 219 if (present) {
hudakz 13:b593a82ce790 220 oneWire.reset();
hudakz 13:b593a82ce790 221 oneWire.skip();
hudakz 13:b593a82ce790 222 oneWire.write(0xBE); // to read Scratchpad
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 223 for (uint8_t i = 0; i < 9; i++) // reading scratchpad registers
hudakz 13:b593a82ce790 224 data[i] = oneWire.read();
hudakz 13:b593a82ce790 225
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 226 if (oneWire.crc8(data, 8) != data[8]) // if calculated CRC does not match the stored one
hudakz 13:b593a82ce790 227 return 2; // return with CRC error
hudakz 13:b593a82ce790 228
hudakz 13:b593a82ce790 229 // Convert the raw bytes to a 16bit unsigned value
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 230 uint16_t *p_word = reinterpret_cast < uint16_t * > (&data[0]);
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 231
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 232 debug_if(DEBUG, "raw = %#x\r\n", *p_word);
hudakz 13:b593a82ce790 233
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 234 if (model_s) {
hudakz 13:b593a82ce790 235 *p_word = *p_word << 3; // 9 bit resolution, max conversion time = 750ms
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 236 if (data[7] == 0x10) {
hudakz 13:b593a82ce790 237
hudakz 13:b593a82ce790 238 // "count remain" gives full 12 bit resolution
hudakz 13:b593a82ce790 239 *p_word = (*p_word & 0xFFF0) + 12 - data[6];
hudakz 13:b593a82ce790 240 }
hudakz 13:b593a82ce790 241
hudakz 13:b593a82ce790 242 // Convert the raw bytes to a 16bit signed fixed point value :
hudakz 13:b593a82ce790 243 // 1 sign bit, 7 integer bits, 8 fractional bits (two's compliment
hudakz 13:b593a82ce790 244 // and the LSB of the 16bit binary number represents 1/256th of a unit).
hudakz 13:b593a82ce790 245 *p_word = *p_word << 4;
hudakz 13:b593a82ce790 246 // Convert to floating point value
hudakz 13:b593a82ce790 247 temp = toFloat(*p_word);
hudakz 13:b593a82ce790 248 return 0; // return with no errors
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 249 } else {
hudakz 13:b593a82ce790 250 uint8_t cfg = (data[4] & 0x60); // default 12bit resolution, max conversion time = 750ms
hudakz 13:b593a82ce790 251
hudakz 13:b593a82ce790 252 // at lower resolution, the low bits are undefined, so let's clear them
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 253 if (cfg == 0x00)
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 254 *p_word = *p_word & ~7; // 9bit resolution, max conversion time = 93.75ms
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 255 else if (cfg == 0x20)
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 256 *p_word = *p_word & ~3; // 10bit resolution, max conversion time = 187.5ms
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 257 else if (cfg == 0x40)
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 258 *p_word = *p_word & ~1; // 11bit resolution, max conversion time = 375ms
hudakz 13:b593a82ce790 259
hudakz 13:b593a82ce790 260 // Convert the raw bytes to a 16bit signed fixed point value :
hudakz 13:b593a82ce790 261 // 1 sign bit, 7 integer bits, 8 fractional bits (two's compliment
hudakz 13:b593a82ce790 262 // and the LSB of the 16bit binary number represents 1/256th of a unit).
hudakz 13:b593a82ce790 263 *p_word = *p_word << 4;
hudakz 13:b593a82ce790 264 // Convert to floating point value
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 265 temp = *p_word;
hudakz 13:b593a82ce790 266 return 0; // return with no errors
hudakz 13:b593a82ce790 267 }
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 268 } else
hudakz 13:b593a82ce790 269 return 1; // error, sensor is not present
hudakz 13:b593a82ce790 270 }
hudakz 13:b593a82ce790 271
hudakz 13:b593a82ce790 272 /**
hudakz 6:518950e436be 273 * @brief Converts a 16-bit signed fixed point value to floating point value
hudakz 6:518950e436be 274 * @note The 16-bit unsigned integer represnts actually
hudakz 6:518950e436be 275 * a 16-bit signed fixed point value:
hudakz 4:adf4e7972d73 276 * 1 sign bit, 7 integer bits, 8 fractional bits (two’s compliment
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 277 * and the LSB of the 16-bit binary number represents 1/256th of a unit).
hudakz 6:518950e436be 278 * @param 16-bit unsigned integer
hudakz 4:adf4e7972d73 279 * @retval Floating point value
hudakz 0:433af64321d5 280 */
hudakz 0:433af64321d5 281 float DS1820::toFloat(uint16_t word) {
lucian@Lucians-MacBook-Pro.local 14:cb585e978f8d 282 if (word & 0x8000)
hudakz 0:433af64321d5 283 return (-float(uint16_t(~word + 1)) / 256.0f);
hudakz 0:433af64321d5 284 else
hudakz 0:433af64321d5 285 return (float(word) / 256.0f);
hudakz 0:433af64321d5 286 }
hudakz 0:433af64321d5 287
hudakz 8:8dfdd1603e4d 288