Руслан Бредун / Mbed 2 deprecated stm32-sensor-base2

test

Dependencies:   mbed Watchdog

Dependents:   STM32-MC_node

DS1820/DS1820.cpp@16:82251ada9b04, 2020-12-14 (annotated)

Committer:
ruslanbredun
Date:
Mon Dec 14 14:13:35 2020 +0000
Revision:
16:82251ada9b04
Parent:
11:32eeb052cda5 
tester

Who changed what in which revision?

UserRevisionLine numberNew contents of line
ommpy 11:32eeb052cda5 1 /*
ommpy 11:32eeb052cda5 2 * Dallas' DS1820 family temperature sensor.
ommpy 11:32eeb052cda5 3 * This library depends on the OneWire library (Dallas' 1-Wire bus protocol implementation)
ommpy 11:32eeb052cda5 4 * available at <http://developer.mbed.org/users/hudakz/code/OneWire/>
ommpy 11:32eeb052cda5 5 *
ommpy 11:32eeb052cda5 6 * Example of use:
ommpy 11:32eeb052cda5 7 *
ommpy 11:32eeb052cda5 8 * Single sensor.
ommpy 11:32eeb052cda5 9 *
ommpy 11:32eeb052cda5 10 * #include "mbed.h"
ommpy 11:32eeb052cda5 11 * #include "DS1820.h"
ommpy 11:32eeb052cda5 12 *
ommpy 11:32eeb052cda5 13 * Serial pc(USBTX, USBRX);
ommpy 11:32eeb052cda5 14 * DigitalOut led(LED1);
ommpy 11:32eeb052cda5 15 * OneWire oneWire(D8); // substitute D8 with actual mbed pin name connected 1-wire bus
ommpy 11:32eeb052cda5 16 * float temp = 0;
ommpy 11:32eeb052cda5 17 * int result = 0;
ommpy 11:32eeb052cda5 18 *
ommpy 11:32eeb052cda5 19 * int main()
ommpy 11:32eeb052cda5 20 * {
ommpy 11:32eeb052cda5 21 * pc.printf("\r\n--Starting--\r\n");
ommpy 11:32eeb052cda5 22 * if (ds1820.begin()) {
ommpy 11:32eeb052cda5 23 * while (1) {
ommpy 11:32eeb052cda5 24 * ds1820.startConversion(); // start temperature conversion from analog to digital
ommpy 11:32eeb052cda5 25 * ThisThread::sleep_for(1000);// let DS1820 complete the temperature conversion
ommpy 11:32eeb052cda5 26 * result = ds1820.read(temp); // read temperature from DS1820 and perform cyclic redundancy check (CRC)
ommpy 11:32eeb052cda5 27 * switch (result) {
ommpy 11:32eeb052cda5 28 * case 0: // no errors -> 'temp' contains the value of measured temperature
ommpy 11:32eeb052cda5 29 * pc.printf("temp = %3.1f%cC\r\n", temp, 176);
ommpy 11:32eeb052cda5 30 * break;
ommpy 11:32eeb052cda5 31 *
ommpy 11:32eeb052cda5 32 * case 1: // no sensor present -> 'temp' is not updated
ommpy 11:32eeb052cda5 33 * pc.printf("no sensor present\n\r");
ommpy 11:32eeb052cda5 34 * break;
ommpy 11:32eeb052cda5 35 *
ommpy 11:32eeb052cda5 36 * case 2: // CRC error -> 'temp' is not updated
ommpy 11:32eeb052cda5 37 * pc.printf("CRC error\r\n");
ommpy 11:32eeb052cda5 38 * }
ommpy 11:32eeb052cda5 39 *
ommpy 11:32eeb052cda5 40 * led = !led;
ommpy 11:32eeb052cda5 41 * }
ommpy 11:32eeb052cda5 42 * }
ommpy 11:32eeb052cda5 43 * else
ommpy 11:32eeb052cda5 44 * pc.printf("No DS1820 sensor found!\r\n");
ommpy 11:32eeb052cda5 45 * }
ommpy 11:32eeb052cda5 46 *
ommpy 11:32eeb052cda5 47 *
ommpy 11:32eeb052cda5 48 * More sensors connected to the same 1-wire bus.
ommpy 11:32eeb052cda5 49 *
ommpy 11:32eeb052cda5 50 * #include "mbed.h"
ommpy 11:32eeb052cda5 51 * #include "DS1820.h"
ommpy 11:32eeb052cda5 52 *
ommpy 11:32eeb052cda5 53 * #define SENSORS_COUNT 64 // number of DS1820 sensors to be connected to the 1-wire bus (max 256)
ommpy 11:32eeb052cda5 54 *
ommpy 11:32eeb052cda5 55 * Serial pc(USBTX, USBRX);
ommpy 11:32eeb052cda5 56 * DigitalOut led(LED1);
ommpy 11:32eeb052cda5 57 * OneWire oneWire(D8); // substitute D8 with actual mbed pin name connected to the DS1820 data pin
ommpy 11:32eeb052cda5 58 * DS1820* ds1820[SENSORS_COUNT];
ommpy 11:32eeb052cda5 59 * int sensors_found = 0; // counts the actually found DS1820 sensors
ommpy 11:32eeb052cda5 60 * float temp = 0;
ommpy 11:32eeb052cda5 61 * int result = 0;
ommpy 11:32eeb052cda5 62 *
ommpy 11:32eeb052cda5 63 * int main() {
ommpy 11:32eeb052cda5 64 * int i = 0;
ommpy 11:32eeb052cda5 65 *
ommpy 11:32eeb052cda5 66 * pc.printf("\r\n Starting \r\n");
ommpy 11:32eeb052cda5 67 * //Enumerate (i.e. detect) DS1820 sensors on the 1-wire bus
ommpy 11:32eeb052cda5 68 * for(i = 0; i < SENSORS_COUNT; i++) {
ommpy 11:32eeb052cda5 69 * ds1820[i] = new DS1820(&oneWire);
ommpy 11:32eeb052cda5 70 * if(!ds1820[i]->begin()) {
ommpy 11:32eeb052cda5 71 * delete ds1820[i];
ommpy 11:32eeb052cda5 72 * break;
ommpy 11:32eeb052cda5 73 * }
ommpy 11:32eeb052cda5 74 * }
ommpy 11:32eeb052cda5 75 *
ommpy 11:32eeb052cda5 76 * sensors_found = i;
ommpy 11:32eeb052cda5 77 *
ommpy 11:32eeb052cda5 78 * if (sensors_found == 0) {
ommpy 11:32eeb052cda5 79 * pc.printf("No DS1820 sensor found!\r\n");
ommpy 11:32eeb052cda5 80 * return -1;
ommpy 11:32eeb052cda5 81 * }
ommpy 11:32eeb052cda5 82 * else
ommpy 11:32eeb052cda5 83 * pc.printf("Found %d sensors.\r\n", sensors_found);
ommpy 11:32eeb052cda5 84 *
ommpy 11:32eeb052cda5 85 * while(1) {
ommpy 11:32eeb052cda5 86 * pc.printf("-------------------\r\n");
ommpy 11:32eeb052cda5 87 * for(i = 0; i < sensors_found; i++)
ommpy 11:32eeb052cda5 88 * ds1820[i]->startConversion(); // start temperature conversion from analog to digital
ommpy 11:32eeb052cda5 89 * ThisThread::sleep_for(1000); // let DS1820s complete the temperature conversion
ommpy 11:32eeb052cda5 90 * for(int i = 0; i < sensors_found; i++) {
ommpy 11:32eeb052cda5 91 * if(ds1820[i]->isPresent())
ommpy 11:32eeb052cda5 92 * pc.printf("temp[%d] = %3.1f%cC\r\n", i, ds1820[i]->read(), 176); // read temperature
ommpy 11:32eeb052cda5 93 * }
ommpy 11:32eeb052cda5 94 * }
ommpy 11:32eeb052cda5 95 * }
ommpy 11:32eeb052cda5 96 *
ommpy 11:32eeb052cda5 97 */
ommpy 11:32eeb052cda5 98
ommpy 11:32eeb052cda5 99 #include "DS1820.h"
ommpy 11:32eeb052cda5 100
ommpy 11:32eeb052cda5 101 #define DEBUG 0
ommpy 11:32eeb052cda5 102
ommpy 11:32eeb052cda5 103 //* Initializing static members
ommpy 11:32eeb052cda5 104 uint8_t DS1820::lastAddr[8] = {0, 0, 0, 0, 0, 0, 0, 0};
ommpy 11:32eeb052cda5 105 /**
ommpy 11:32eeb052cda5 106 * @brief Constructs a generic DS1820 sensor
ommpy 11:32eeb052cda5 107 * @note begin() must be called to detect and initialize the actual model
ommpy 11:32eeb052cda5 108 * @param pin: Name of data pin
ommpy 11:32eeb052cda5 109 * @retval
ommpy 11:32eeb052cda5 110 */
ommpy 11:32eeb052cda5 111 DS1820::DS1820(PinName pin, int sample_point_us /* = 13 */) {
ommpy 11:32eeb052cda5 112 oneWire = new OneWire(pin, sample_point_us);
ommpy 11:32eeb052cda5 113 present = false;
ommpy 11:32eeb052cda5 114 model_s = false;
ommpy 11:32eeb052cda5 115 }
ommpy 11:32eeb052cda5 116
ommpy 11:32eeb052cda5 117 /**
ommpy 11:32eeb052cda5 118 * @brief Constructs a generic DS1820 sensor
ommpy 11:32eeb052cda5 119 * @note begin() must be called to detect and initialize the actual model
ommpy 11:32eeb052cda5 120 * @param pin: Name of data pin
ommpy 11:32eeb052cda5 121 * @retval
ommpy 11:32eeb052cda5 122 */
ommpy 11:32eeb052cda5 123 DS1820::DS1820(OneWire* wire) :
ommpy 11:32eeb052cda5 124 oneWire(wire) {
ommpy 11:32eeb052cda5 125 present = false;
ommpy 11:32eeb052cda5 126 model_s = false;
ommpy 11:32eeb052cda5 127 }
ommpy 11:32eeb052cda5 128
ommpy 11:32eeb052cda5 129 /**
ommpy 11:32eeb052cda5 130 * @brief Detects and initializes the actual DS1820 model
ommpy 11:32eeb052cda5 131 * @note
ommpy 11:32eeb052cda5 132 * @param
ommpy 11:32eeb052cda5 133 * @retval true: if a DS1820 family sensor was detected and initialized
ommpy 11:32eeb052cda5 134 false: otherwise
ommpy 11:32eeb052cda5 135 */
ommpy 11:32eeb052cda5 136 bool DS1820::begin(void) {
ommpy 11:32eeb052cda5 137 #if DEBUG
ommpy 11:32eeb052cda5 138 printf("lastAddr =");
ommpy 11:32eeb052cda5 139 for(uint8_t i = 0; i < 8; i++) {
ommpy 11:32eeb052cda5 140 printf(" %x", lastAddr[i]);
ommpy 11:32eeb052cda5 141 }
ommpy 11:32eeb052cda5 142 printf("\r\n");
ommpy 11:32eeb052cda5 143 #endif
ommpy 11:32eeb052cda5 144 if(!oneWire->search(lastAddr)) {
ommpy 11:32eeb052cda5 145 #if DEBUG
ommpy 11:32eeb052cda5 146 printf("No addresses.\r\n");
ommpy 11:32eeb052cda5 147 #endif
ommpy 11:32eeb052cda5 148 oneWire->reset_search();
ommpy 11:32eeb052cda5 149 //ThisThread::sleep_for(250);
ommpy 11:32eeb052cda5 150 wait_ms (250);
ommpy 11:32eeb052cda5 151 return false;
ommpy 11:32eeb052cda5 152 }
ommpy 11:32eeb052cda5 153
ommpy 11:32eeb052cda5 154 for (int i = 0; i < 8; i++)
ommpy 11:32eeb052cda5 155 addr[i] = lastAddr[i];
ommpy 11:32eeb052cda5 156
ommpy 11:32eeb052cda5 157 #if DEBUG
ommpy 11:32eeb052cda5 158 printf("ROM =");
ommpy 11:32eeb052cda5 159 for(uint8_t i = 0; i < 8; i++) {
ommpy 11:32eeb052cda5 160 printf(" %x", addr[i]);
ommpy 11:32eeb052cda5 161 }
ommpy 11:32eeb052cda5 162 printf("\r\n");
ommpy 11:32eeb052cda5 163 #endif
ommpy 11:32eeb052cda5 164
ommpy 11:32eeb052cda5 165 if(OneWire::crc8(addr, 7) == addr[7]) {
ommpy 11:32eeb052cda5 166 present = true;
ommpy 11:32eeb052cda5 167
ommpy 11:32eeb052cda5 168 // the first ROM byte indicates which chip
ommpy 11:32eeb052cda5 169 switch(addr[0]) {
ommpy 11:32eeb052cda5 170 case 0x10:
ommpy 11:32eeb052cda5 171 model_s = true;
ommpy 11:32eeb052cda5 172 #if DEBUG
ommpy 11:32eeb052cda5 173 printf("DS18S20 or old DS1820\r\n");
ommpy 11:32eeb052cda5 174 #endif
ommpy 11:32eeb052cda5 175 break;
ommpy 11:32eeb052cda5 176
ommpy 11:32eeb052cda5 177 case 0x28:
ommpy 11:32eeb052cda5 178 model_s = false;
ommpy 11:32eeb052cda5 179 #if DEBUG
ommpy 11:32eeb052cda5 180 printf("DS18B20\r\n");
ommpy 11:32eeb052cda5 181 #endif
ommpy 11:32eeb052cda5 182 break;
ommpy 11:32eeb052cda5 183
ommpy 11:32eeb052cda5 184 case 0x22:
ommpy 11:32eeb052cda5 185 model_s = false;
ommpy 11:32eeb052cda5 186 #if DEBUG
ommpy 11:32eeb052cda5 187 printf("DS1822\r\n");
ommpy 11:32eeb052cda5 188 #endif
ommpy 11:32eeb052cda5 189 break;
ommpy 11:32eeb052cda5 190
ommpy 11:32eeb052cda5 191 default:
ommpy 11:32eeb052cda5 192 present = false;
ommpy 11:32eeb052cda5 193 #if DEBUG
ommpy 11:32eeb052cda5 194 printf("Device doesn't belong to the DS1820 family\r\n");
ommpy 11:32eeb052cda5 195 #endif
ommpy 11:32eeb052cda5 196 return false;
ommpy 11:32eeb052cda5 197 }
ommpy 11:32eeb052cda5 198 return true;
ommpy 11:32eeb052cda5 199 }
ommpy 11:32eeb052cda5 200 else {
ommpy 11:32eeb052cda5 201 #if DEBUG
ommpy 11:32eeb052cda5 202 printf("Invalid CRC!\r\n");
ommpy 11:32eeb052cda5 203 #endif
ommpy 11:32eeb052cda5 204 return false;
ommpy 11:32eeb052cda5 205 }
ommpy 11:32eeb052cda5 206 }
ommpy 11:32eeb052cda5 207
ommpy 11:32eeb052cda5 208 /**
ommpy 11:32eeb052cda5 209 * @brief Informs about presence of a DS1820 sensor.
ommpy 11:32eeb052cda5 210 * @note begin() shall be called before using this function
ommpy 11:32eeb052cda5 211 * if a generic DS1820 instance was created by the user.
ommpy 11:32eeb052cda5 212 * No need to call begin() for a specific DS1820 instance.
ommpy 11:32eeb052cda5 213 * @param
ommpy 11:32eeb052cda5 214 * @retval true: when a DS1820 sensor is present
ommpy 11:32eeb052cda5 215 * false: otherwise
ommpy 11:32eeb052cda5 216 */
ommpy 11:32eeb052cda5 217 bool DS1820::isPresent(void) {
ommpy 11:32eeb052cda5 218 return present;
ommpy 11:32eeb052cda5 219 }
ommpy 11:32eeb052cda5 220
ommpy 11:32eeb052cda5 221 /**
ommpy 11:32eeb052cda5 222 * @brief Sets temperature-to-digital conversion resolution.
ommpy 11:32eeb052cda5 223 * @note The configuration register allows the user to set the resolution
ommpy 11:32eeb052cda5 224 * of the temperature-to-digital conversion to 9, 10, 11, or 12 bits.
ommpy 11:32eeb052cda5 225 * Defaults to 12-bit resolution for DS18B20.
ommpy 11:32eeb052cda5 226 * DS18S20 allows only 9-bit resolution.
ommpy 11:32eeb052cda5 227 * @param res: Resolution of the temperature-to-digital conversion in bits.
ommpy 11:32eeb052cda5 228 * @retval
ommpy 11:32eeb052cda5 229 */
ommpy 11:32eeb052cda5 230 void DS1820::setResolution(uint8_t res) {
ommpy 11:32eeb052cda5 231 // keep resolution within limits
ommpy 11:32eeb052cda5 232 if(res > 12)
ommpy 11:32eeb052cda5 233 res = 12;
ommpy 11:32eeb052cda5 234 if(res < 9)
ommpy 11:32eeb052cda5 235 res = 9;
ommpy 11:32eeb052cda5 236 if(model_s)
ommpy 11:32eeb052cda5 237 res = 9;
ommpy 11:32eeb052cda5 238
ommpy 11:32eeb052cda5 239 oneWire->reset();
ommpy 11:32eeb052cda5 240 oneWire->select(addr);
ommpy 11:32eeb052cda5 241 oneWire->write_byte(0xBE); // to read Scratchpad
ommpy 11:32eeb052cda5 242 for(uint8_t i = 0; i < 9; i++) // read Scratchpad bytes
ommpy 11:32eeb052cda5 243 data[i] = oneWire->read_byte();
ommpy 11:32eeb052cda5 244
ommpy 11:32eeb052cda5 245 data[4] |= (res - 9) << 5; // update configuration byte (set resolution)
ommpy 11:32eeb052cda5 246 oneWire->reset();
ommpy 11:32eeb052cda5 247 oneWire->select(addr);
ommpy 11:32eeb052cda5 248 oneWire->write_byte(0x4E); // to write into Scratchpad
ommpy 11:32eeb052cda5 249 for(uint8_t i = 2; i < 5; i++) // write three bytes (2nd, 3rd, 4th) into Scratchpad
ommpy 11:32eeb052cda5 250 oneWire->write_byte(data[i]);
ommpy 11:32eeb052cda5 251 }
ommpy 11:32eeb052cda5 252
ommpy 11:32eeb052cda5 253 /**
ommpy 11:32eeb052cda5 254 * @brief Starts temperature conversion
ommpy 11:32eeb052cda5 255 * @note The time to complete the converion depends on the selected resolution:
ommpy 11:32eeb052cda5 256 * 9-bit resolution -> max conversion time = 93.75ms
ommpy 11:32eeb052cda5 257 * 10-bit resolution -> max conversion time = 187.5ms
ommpy 11:32eeb052cda5 258 * 11-bit resolution -> max conversion time = 375ms
ommpy 11:32eeb052cda5 259 * 12-bit resolution -> max conversion time = 750ms
ommpy 11:32eeb052cda5 260 * @param
ommpy 11:32eeb052cda5 261 * @retval
ommpy 11:32eeb052cda5 262 */
ommpy 11:32eeb052cda5 263 void DS1820::startConversion(void) {
ommpy 11:32eeb052cda5 264 if(present) {
ommpy 11:32eeb052cda5 265 oneWire->reset();
ommpy 11:32eeb052cda5 266 oneWire->select(addr);
ommpy 11:32eeb052cda5 267 oneWire->write_byte(0x44); //start temperature conversion
ommpy 11:32eeb052cda5 268 }
ommpy 11:32eeb052cda5 269 }
ommpy 11:32eeb052cda5 270
ommpy 11:32eeb052cda5 271 /**
ommpy 11:32eeb052cda5 272 * @brief Reads temperature from the chip's Scratchpad
ommpy 11:32eeb052cda5 273 * @note
ommpy 11:32eeb052cda5 274 * @param
ommpy 11:32eeb052cda5 275 * @retval Floating point temperature value
ommpy 11:32eeb052cda5 276 */
ommpy 11:32eeb052cda5 277 float DS1820::read(void) {
ommpy 11:32eeb052cda5 278 if(present) {
ommpy 11:32eeb052cda5 279 oneWire->reset();
ommpy 11:32eeb052cda5 280 oneWire->select(addr);
ommpy 11:32eeb052cda5 281 oneWire->write_byte(0xBE); // to read Scratchpad
ommpy 11:32eeb052cda5 282 for(uint8_t i = 0; i < 9; i++) // reading scratchpad registers
ommpy 11:32eeb052cda5 283 data[i] = oneWire->read_byte();
ommpy 11:32eeb052cda5 284
ommpy 11:32eeb052cda5 285 // Convert the raw bytes to a 16-bit unsigned value
ommpy 11:32eeb052cda5 286 uint16_t* p_word = reinterpret_cast < uint16_t * > (&data[0]);
ommpy 11:32eeb052cda5 287
ommpy 11:32eeb052cda5 288 #if DEBUG
ommpy 11:32eeb052cda5 289 printf("raw = %#x\r\n", *p_word);
ommpy 11:32eeb052cda5 290 #endif
ommpy 11:32eeb052cda5 291
ommpy 11:32eeb052cda5 292 if(model_s) {
ommpy 11:32eeb052cda5 293 *p_word = *p_word << 3; // 9-bit resolution
ommpy 11:32eeb052cda5 294 if(data[7] == 0x10) {
ommpy 11:32eeb052cda5 295
ommpy 11:32eeb052cda5 296 // "count remain" gives full 12-bit resolution
ommpy 11:32eeb052cda5 297 *p_word = (*p_word & 0xFFF0) + 12 - data[6];
ommpy 11:32eeb052cda5 298 }
ommpy 11:32eeb052cda5 299 }
ommpy 11:32eeb052cda5 300 else {
ommpy 11:32eeb052cda5 301 uint8_t cfg = (data[4] & 0x60); // default 12-bit resolution
ommpy 11:32eeb052cda5 302
ommpy 11:32eeb052cda5 303 // at lower resolution, the low bits are undefined, so let's clear them
ommpy 11:32eeb052cda5 304 if(cfg == 0x00)
ommpy 11:32eeb052cda5 305 *p_word = *p_word &~7; // 9-bit resolution
ommpy 11:32eeb052cda5 306 else
ommpy 11:32eeb052cda5 307 if(cfg == 0x20)
ommpy 11:32eeb052cda5 308 *p_word = *p_word &~3; // 10-bit resolution
ommpy 11:32eeb052cda5 309 else
ommpy 11:32eeb052cda5 310 if(cfg == 0x40)
ommpy 11:32eeb052cda5 311 *p_word = *p_word &~1; // 11-bit resolution
ommpy 11:32eeb052cda5 312
ommpy 11:32eeb052cda5 313 }
ommpy 11:32eeb052cda5 314
ommpy 11:32eeb052cda5 315 // Convert the raw bytes to a 16-bit signed fixed point value :
ommpy 11:32eeb052cda5 316 // 1 sign bit, 7 integer bits, 8 fractional bits (two’s compliment
ommpy 11:32eeb052cda5 317 // and the LSB of the 16-bit binary number represents 1/256th of a unit).
ommpy 11:32eeb052cda5 318 *p_word = *p_word << 4;
ommpy 11:32eeb052cda5 319
ommpy 11:32eeb052cda5 320 // Convert to floating point value
ommpy 11:32eeb052cda5 321 return(toFloat(*p_word));
ommpy 11:32eeb052cda5 322 }
ommpy 11:32eeb052cda5 323 else
ommpy 11:32eeb052cda5 324 return 0;
ommpy 11:32eeb052cda5 325 }
ommpy 11:32eeb052cda5 326
ommpy 11:32eeb052cda5 327 /**
ommpy 11:32eeb052cda5 328 * @brief Reads temperature from chip's scratchpad.
ommpy 11:32eeb052cda5 329 * @note Verifies data integrity by calculating cyclic redundancy check (CRC).
ommpy 11:32eeb052cda5 330 * If the calculated CRC dosn't match the one stored in chip's scratchpad register
ommpy 11:32eeb052cda5 331 * the temperature variable is not updated and CRC error code is returned.
ommpy 11:32eeb052cda5 332 * @param temp: The temperature variable to be updated by this routine.
ommpy 11:32eeb052cda5 333 * (It's passed as reference to floating point.)
ommpy 11:32eeb052cda5 334 * @retval error code:
ommpy 11:32eeb052cda5 335 * 0 - no errors ('temp' contains the temperature measured)
ommpy 11:32eeb052cda5 336 * 1 - sensor not present ('temp' is not updated)
ommpy 11:32eeb052cda5 337 * 2 - CRC error ('temp' is not updated)
ommpy 11:32eeb052cda5 338 */
ommpy 11:32eeb052cda5 339 uint8_t DS1820::read(float& temp) {
ommpy 11:32eeb052cda5 340 if(present) {
ommpy 11:32eeb052cda5 341 oneWire->reset();
ommpy 11:32eeb052cda5 342 oneWire->select(addr);
ommpy 11:32eeb052cda5 343 oneWire->write_byte(0xBE); // to read Scratchpad
ommpy 11:32eeb052cda5 344 for(uint8_t i = 0; i < 9; i++) // reading scratchpad registers
ommpy 11:32eeb052cda5 345 data[i] = oneWire->read_byte();
ommpy 11:32eeb052cda5 346
ommpy 11:32eeb052cda5 347 if(oneWire->crc8(data, 8) != data[8]) // if calculated CRC does not match the stored one
ommpy 11:32eeb052cda5 348 {
ommpy 11:32eeb052cda5 349 #if DEBUG
ommpy 11:32eeb052cda5 350 for(uint8_t i = 0; i < 9; i++)
ommpy 11:32eeb052cda5 351 printf("data[%d]=0x%.2x\r\n", i, data[i]);
ommpy 11:32eeb052cda5 352 #endif
ommpy 11:32eeb052cda5 353 return 2; // return with CRC error
ommpy 11:32eeb052cda5 354 }
ommpy 11:32eeb052cda5 355
ommpy 11:32eeb052cda5 356 // Convert the raw bytes to a 16bit unsigned value
ommpy 11:32eeb052cda5 357 uint16_t* p_word = reinterpret_cast < uint16_t * > (&data[0]);
ommpy 11:32eeb052cda5 358
ommpy 11:32eeb052cda5 359 #if DEBUG
ommpy 11:32eeb052cda5 360 printf("raw = %#x\r\n", *p_word);
ommpy 11:32eeb052cda5 361 #endif
ommpy 11:32eeb052cda5 362
ommpy 11:32eeb052cda5 363 if(model_s) {
ommpy 11:32eeb052cda5 364 *p_word = *p_word << 3; // 9 bit resolution, max conversion time = 750ms
ommpy 11:32eeb052cda5 365 if(data[7] == 0x10) {
ommpy 11:32eeb052cda5 366
ommpy 11:32eeb052cda5 367 // "count remain" gives full 12 bit resolution
ommpy 11:32eeb052cda5 368 *p_word = (*p_word & 0xFFF0) + 12 - data[6];
ommpy 11:32eeb052cda5 369 }
ommpy 11:32eeb052cda5 370
ommpy 11:32eeb052cda5 371 // Convert the raw bytes to a 16bit signed fixed point value :
ommpy 11:32eeb052cda5 372 // 1 sign bit, 7 integer bits, 8 fractional bits (two's compliment
ommpy 11:32eeb052cda5 373 // and the LSB of the 16bit binary number represents 1/256th of a unit).
ommpy 11:32eeb052cda5 374 *p_word = *p_word << 4;
ommpy 11:32eeb052cda5 375 // Convert to floating point value
ommpy 11:32eeb052cda5 376 temp = toFloat(*p_word);
ommpy 11:32eeb052cda5 377 return 0; // return with no errors
ommpy 11:32eeb052cda5 378 }
ommpy 11:32eeb052cda5 379 else {
ommpy 11:32eeb052cda5 380 uint8_t cfg = (data[4] & 0x60); // default 12bit resolution, max conversion time = 750ms
ommpy 11:32eeb052cda5 381
ommpy 11:32eeb052cda5 382 // at lower resolution, the low bits are undefined, so let's clear them
ommpy 11:32eeb052cda5 383 if(cfg == 0x00)
ommpy 11:32eeb052cda5 384 *p_word = *p_word &~7; // 9bit resolution, max conversion time = 93.75ms
ommpy 11:32eeb052cda5 385 else
ommpy 11:32eeb052cda5 386 if(cfg == 0x20)
ommpy 11:32eeb052cda5 387 *p_word = *p_word &~3; // 10bit resolution, max conversion time = 187.5ms
ommpy 11:32eeb052cda5 388 else
ommpy 11:32eeb052cda5 389 if(cfg == 0x40)
ommpy 11:32eeb052cda5 390 *p_word = *p_word &~1; // 11bit resolution, max conversion time = 375ms
ommpy 11:32eeb052cda5 391
ommpy 11:32eeb052cda5 392 // Convert the raw bytes to a 16bit signed fixed point value :
ommpy 11:32eeb052cda5 393 // 1 sign bit, 7 integer bits, 8 fractional bits (two's complement
ommpy 11:32eeb052cda5 394 // and the LSB of the 16bit binary number represents 1/256th of a unit).
ommpy 11:32eeb052cda5 395 *p_word = *p_word << 4;
ommpy 11:32eeb052cda5 396 // Convert to floating point value
ommpy 11:32eeb052cda5 397 temp = toFloat(*p_word);
ommpy 11:32eeb052cda5 398 return 0; // return with no errors
ommpy 11:32eeb052cda5 399 }
ommpy 11:32eeb052cda5 400 }
ommpy 11:32eeb052cda5 401 else
ommpy 11:32eeb052cda5 402 return 1; // error, sensor is not present
ommpy 11:32eeb052cda5 403 }
ommpy 11:32eeb052cda5 404
ommpy 11:32eeb052cda5 405 /**
ommpy 11:32eeb052cda5 406 * @brief Converts a 16-bit signed fixed point value to floating point value
ommpy 11:32eeb052cda5 407 * @note The 16-bit unsigned integer represnts actually
ommpy 11:32eeb052cda5 408 * a 16-bit signed fixed point value:
ommpy 11:32eeb052cda5 409 * 1 sign bit, 7 integer bits, 8 fractional bits (two’s complement
ommpy 11:32eeb052cda5 410 * and the LSB of the 16-bit binary number represents 1/256th of a unit).
ommpy 11:32eeb052cda5 411 * @param 16-bit unsigned integer
ommpy 11:32eeb052cda5 412 * @retval Floating point value
ommpy 11:32eeb052cda5 413 */
ommpy 11:32eeb052cda5 414 float DS1820::toFloat(uint16_t word) {
ommpy 11:32eeb052cda5 415 if(word & 0x8000)
ommpy 11:32eeb052cda5 416 return (-float(uint16_t(~word + 1)) / 256.0f);
ommpy 11:32eeb052cda5 417 else
ommpy 11:32eeb052cda5 418 return (float(word) / 256.0f);
ommpy 11:32eeb052cda5 419 }
ommpy 11:32eeb052cda5 420