Team Diana
DS1820.cpp@22:44b91be5b3f6, 2019-06-10 (annotated)
- Committer:
- Alessio_Zaino
- Date:
- Mon Jun 10 12:49:37 2019 +0000
- Revision:
- 22:44b91be5b3f6
- Parent:
- 20:98c261bcb399
Still in developing
Who changed what in which revision?
User | Revision | Line number | New contents of line |
---|---|---|---|
hudakz | 3:a250babd0a9f | 1 | |
hudakz | 0:433af64321d5 | 2 | #include "DS1820.h" |
hudakz | 0:433af64321d5 | 3 | |
hudakz | 20:98c261bcb399 | 4 | #define DEBUG 0 |
hudakz | 20:98c261bcb399 | 5 | |
hudakz | 20:98c261bcb399 | 6 | //* Initializing static members |
hudakz | 20:98c261bcb399 | 7 | uint8_t DS1820::lastAddr[8] = {0, 0, 0, 0, 0, 0, 0, 0}; |
hudakz | 20:98c261bcb399 | 8 | /** |
hudakz | 20:98c261bcb399 | 9 | * @brief Constructs a generic DS1820 sensor |
hudakz | 20:98c261bcb399 | 10 | * @note begin() must be called to detect and initialize the actual model |
hudakz | 20:98c261bcb399 | 11 | * @param pin: Name of data pin |
hudakz | 20:98c261bcb399 | 12 | * @retval |
hudakz | 20:98c261bcb399 | 13 | */ |
hudakz | 20:98c261bcb399 | 14 | DS1820::DS1820(PinName pin) { |
hudakz | 20:98c261bcb399 | 15 | oneWire = new OneWire(pin); |
hudakz | 20:98c261bcb399 | 16 | present = false; |
hudakz | 20:98c261bcb399 | 17 | model_s = false; |
hudakz | 20:98c261bcb399 | 18 | } |
hudakz | 0:433af64321d5 | 19 | |
hudakz | 0:433af64321d5 | 20 | /** |
hudakz | 0:433af64321d5 | 21 | * @brief Constructs a generic DS1820 sensor |
hudakz | 0:433af64321d5 | 22 | * @note begin() must be called to detect and initialize the actual model |
hudakz | 3:a250babd0a9f | 23 | * @param pin: Name of data pin |
hudakz | 0:433af64321d5 | 24 | * @retval |
hudakz | 0:433af64321d5 | 25 | */ |
hudakz | 20:98c261bcb399 | 26 | DS1820::DS1820(OneWire* wire) : |
hudakz | 20:98c261bcb399 | 27 | oneWire(wire) { |
hudakz | 8:8dfdd1603e4d | 28 | present = false; |
hudakz | 8:8dfdd1603e4d | 29 | model_s = false; |
hudakz | 0:433af64321d5 | 30 | } |
hudakz | 0:433af64321d5 | 31 | |
hudakz | 0:433af64321d5 | 32 | /** |
hudakz | 0:433af64321d5 | 33 | * @brief Detects and initializes the actual DS1820 model |
hudakz | 0:433af64321d5 | 34 | * @note |
hudakz | 0:433af64321d5 | 35 | * @param |
hudakz | 0:433af64321d5 | 36 | * @retval true: if a DS1820 family sensor was detected and initialized |
hudakz | 0:433af64321d5 | 37 | false: otherwise |
hudakz | 0:433af64321d5 | 38 | */ |
hudakz | 0:433af64321d5 | 39 | bool DS1820::begin(void) { |
hudakz | 20:98c261bcb399 | 40 | #if DEBUG |
hudakz | 20:98c261bcb399 | 41 | printf("lastAddr ="); |
hudakz | 20:98c261bcb399 | 42 | for(uint8_t i = 0; i < 8; i++) { |
hudakz | 20:98c261bcb399 | 43 | printf(" %x", lastAddr[i]); |
hudakz | 20:98c261bcb399 | 44 | } |
hudakz | 20:98c261bcb399 | 45 | printf("\r\n"); |
hudakz | 20:98c261bcb399 | 46 | #endif |
hudakz | 20:98c261bcb399 | 47 | if(!oneWire->search(lastAddr)) { |
hudakz | 0:433af64321d5 | 48 | #if DEBUG |
hudakz | 17:9ff584b9809f | 49 | printf("No addresses.\r\n"); |
hudakz | 0:433af64321d5 | 50 | #endif |
hudakz | 20:98c261bcb399 | 51 | oneWire->reset_search(); |
hudakz | 0:433af64321d5 | 52 | wait_ms(250); |
hudakz | 0:433af64321d5 | 53 | return false; |
hudakz | 0:433af64321d5 | 54 | } |
hudakz | 20:98c261bcb399 | 55 | |
hudakz | 20:98c261bcb399 | 56 | for (int i = 0; i < 8; i++) |
hudakz | 20:98c261bcb399 | 57 | addr[i] = lastAddr[i]; |
hudakz | 0:433af64321d5 | 58 | |
hudakz | 0:433af64321d5 | 59 | #if DEBUG |
hudakz | 17:9ff584b9809f | 60 | printf("ROM ="); |
hudakz | 0:433af64321d5 | 61 | for(uint8_t i = 0; i < 8; i++) { |
hudakz | 17:9ff584b9809f | 62 | printf(" %x", addr[i]); |
hudakz | 0:433af64321d5 | 63 | } |
hudakz | 17:9ff584b9809f | 64 | printf("\r\n"); |
hudakz | 0:433af64321d5 | 65 | #endif |
hudakz | 0:433af64321d5 | 66 | |
hudakz | 0:433af64321d5 | 67 | if(OneWire::crc8(addr, 7) == addr[7]) { |
hudakz | 8:8dfdd1603e4d | 68 | present = true; |
hudakz | 0:433af64321d5 | 69 | |
hudakz | 0:433af64321d5 | 70 | // the first ROM byte indicates which chip |
hudakz | 0:433af64321d5 | 71 | switch(addr[0]) { |
hudakz | 0:433af64321d5 | 72 | case 0x10: |
hudakz | 8:8dfdd1603e4d | 73 | model_s = true; |
hudakz | 0:433af64321d5 | 74 | #if DEBUG |
hudakz | 17:9ff584b9809f | 75 | printf("DS18S20 or old DS1820\r\n"); |
hudakz | 0:433af64321d5 | 76 | #endif |
hudakz | 0:433af64321d5 | 77 | break; |
hudakz | 0:433af64321d5 | 78 | |
hudakz | 0:433af64321d5 | 79 | case 0x28: |
hudakz | 8:8dfdd1603e4d | 80 | model_s = false; |
hudakz | 0:433af64321d5 | 81 | #if DEBUG |
hudakz | 17:9ff584b9809f | 82 | printf("DS18B20\r\n"); |
hudakz | 0:433af64321d5 | 83 | #endif |
hudakz | 0:433af64321d5 | 84 | break; |
hudakz | 0:433af64321d5 | 85 | |
hudakz | 0:433af64321d5 | 86 | case 0x22: |
hudakz | 8:8dfdd1603e4d | 87 | model_s = false; |
hudakz | 0:433af64321d5 | 88 | #if DEBUG |
hudakz | 17:9ff584b9809f | 89 | printf("DS1822\r\n"); |
hudakz | 0:433af64321d5 | 90 | #endif |
hudakz | 0:433af64321d5 | 91 | break; |
hudakz | 0:433af64321d5 | 92 | |
hudakz | 0:433af64321d5 | 93 | default: |
hudakz | 8:8dfdd1603e4d | 94 | present = false; |
hudakz | 0:433af64321d5 | 95 | #if DEBUG |
hudakz | 17:9ff584b9809f | 96 | printf("Device doesn't belong to the DS1820 family\r\n"); |
hudakz | 2:b7ad1da7331a | 97 | #endif |
hudakz | 0:433af64321d5 | 98 | return false; |
hudakz | 0:433af64321d5 | 99 | } |
hudakz | 0:433af64321d5 | 100 | return true; |
hudakz | 0:433af64321d5 | 101 | } |
hudakz | 2:b7ad1da7331a | 102 | else { |
hudakz | 0:433af64321d5 | 103 | #if DEBUG |
hudakz | 17:9ff584b9809f | 104 | printf("Invalid CRC!\r\n"); |
hudakz | 2:b7ad1da7331a | 105 | #endif |
hudakz | 0:433af64321d5 | 106 | return false; |
hudakz | 0:433af64321d5 | 107 | } |
hudakz | 0:433af64321d5 | 108 | } |
hudakz | 0:433af64321d5 | 109 | |
hudakz | 0:433af64321d5 | 110 | /** |
hudakz | 8:8dfdd1603e4d | 111 | * @brief Informs about presence of a DS1820 sensor. |
hudakz | 8:8dfdd1603e4d | 112 | * @note begin() shall be called before using this function |
hudakz | 8:8dfdd1603e4d | 113 | * if a generic DS1820 instance was created by the user. |
hudakz | 8:8dfdd1603e4d | 114 | * No need to call begin() for a specific DS1820 instance. |
hudakz | 8:8dfdd1603e4d | 115 | * @param |
hudakz | 8:8dfdd1603e4d | 116 | * @retval true: when a DS1820 sensor is present |
hudakz | 8:8dfdd1603e4d | 117 | * false: otherwise |
hudakz | 8:8dfdd1603e4d | 118 | */ |
hudakz | 8:8dfdd1603e4d | 119 | bool DS1820::isPresent(void) { |
hudakz | 8:8dfdd1603e4d | 120 | return present; |
hudakz | 8:8dfdd1603e4d | 121 | } |
hudakz | 8:8dfdd1603e4d | 122 | |
hudakz | 8:8dfdd1603e4d | 123 | /** |
hudakz | 6:518950e436be | 124 | * @brief Sets temperature-to-digital conversion resolution. |
hudakz | 4:adf4e7972d73 | 125 | * @note The configuration register allows the user to set the resolution |
hudakz | 6:518950e436be | 126 | * of the temperature-to-digital conversion to 9, 10, 11, or 12 bits. |
hudakz | 6:518950e436be | 127 | * Defaults to 12-bit resolution for DS18B20. |
hudakz | 6:518950e436be | 128 | * DS18S20 allows only 9-bit resolution. |
hudakz | 6:518950e436be | 129 | * @param res: Resolution of the temperature-to-digital conversion in bits. |
hudakz | 4:adf4e7972d73 | 130 | * @retval |
hudakz | 4:adf4e7972d73 | 131 | */ |
hudakz | 4:adf4e7972d73 | 132 | void DS1820::setResolution(uint8_t res) { |
hudakz | 4:adf4e7972d73 | 133 | // keep resolution within limits |
hudakz | 4:adf4e7972d73 | 134 | if(res > 12) |
hudakz | 4:adf4e7972d73 | 135 | res = 12; |
hudakz | 4:adf4e7972d73 | 136 | if(res < 9) |
hudakz | 4:adf4e7972d73 | 137 | res = 9; |
hudakz | 8:8dfdd1603e4d | 138 | if(model_s) |
hudakz | 4:adf4e7972d73 | 139 | res = 9; |
hudakz | 4:adf4e7972d73 | 140 | |
hudakz | 20:98c261bcb399 | 141 | oneWire->reset(); |
hudakz | 20:98c261bcb399 | 142 | oneWire->select(addr); |
hudakz | 20:98c261bcb399 | 143 | oneWire->write_byte(0xBE); // to read Scratchpad |
hudakz | 4:adf4e7972d73 | 144 | for(uint8_t i = 0; i < 9; i++) // read Scratchpad bytes |
hudakz | 20:98c261bcb399 | 145 | data[i] = oneWire->read_byte(); |
hudakz | 4:adf4e7972d73 | 146 | |
hudakz | 4:adf4e7972d73 | 147 | data[4] |= (res - 9) << 5; // update configuration byte (set resolution) |
hudakz | 20:98c261bcb399 | 148 | oneWire->reset(); |
hudakz | 20:98c261bcb399 | 149 | oneWire->select(addr); |
hudakz | 20:98c261bcb399 | 150 | oneWire->write_byte(0x4E); // to write into Scratchpad |
hudakz | 4:adf4e7972d73 | 151 | for(uint8_t i = 2; i < 5; i++) // write three bytes (2nd, 3rd, 4th) into Scratchpad |
hudakz | 20:98c261bcb399 | 152 | oneWire->write_byte(data[i]); |
hudakz | 4:adf4e7972d73 | 153 | } |
hudakz | 4:adf4e7972d73 | 154 | |
hudakz | 4:adf4e7972d73 | 155 | /** |
hudakz | 0:433af64321d5 | 156 | * @brief Starts temperature conversion |
hudakz | 6:518950e436be | 157 | * @note The time to complete the converion depends on the selected resolution: |
hudakz | 6:518950e436be | 158 | * 9-bit resolution -> max conversion time = 93.75ms |
hudakz | 6:518950e436be | 159 | * 10-bit resolution -> max conversion time = 187.5ms |
hudakz | 6:518950e436be | 160 | * 11-bit resolution -> max conversion time = 375ms |
hudakz | 6:518950e436be | 161 | * 12-bit resolution -> max conversion time = 750ms |
hudakz | 0:433af64321d5 | 162 | * @param |
hudakz | 0:433af64321d5 | 163 | * @retval |
hudakz | 0:433af64321d5 | 164 | */ |
hudakz | 0:433af64321d5 | 165 | void DS1820::startConversion(void) { |
hudakz | 0:433af64321d5 | 166 | if(present) { |
hudakz | 20:98c261bcb399 | 167 | oneWire->reset(); |
hudakz | 20:98c261bcb399 | 168 | oneWire->select(addr); |
hudakz | 20:98c261bcb399 | 169 | oneWire->write_byte(0x44); //start temperature conversion |
hudakz | 0:433af64321d5 | 170 | } |
hudakz | 0:433af64321d5 | 171 | } |
hudakz | 0:433af64321d5 | 172 | |
hudakz | 0:433af64321d5 | 173 | /** |
hudakz | 6:518950e436be | 174 | * @brief Reads temperature from the chip's Scratchpad |
hudakz | 0:433af64321d5 | 175 | * @note |
hudakz | 0:433af64321d5 | 176 | * @param |
hudakz | 0:433af64321d5 | 177 | * @retval Floating point temperature value |
hudakz | 0:433af64321d5 | 178 | */ |
hudakz | 0:433af64321d5 | 179 | float DS1820::read(void) { |
hudakz | 0:433af64321d5 | 180 | if(present) { |
hudakz | 20:98c261bcb399 | 181 | oneWire->reset(); |
hudakz | 20:98c261bcb399 | 182 | oneWire->select(addr); |
hudakz | 20:98c261bcb399 | 183 | oneWire->write_byte(0xBE); // to read Scratchpad |
hudakz | 17:9ff584b9809f | 184 | for(uint8_t i = 0; i < 9; i++) // reading scratchpad registers |
hudakz | 20:98c261bcb399 | 185 | data[i] = oneWire->read_byte(); |
hudakz | 0:433af64321d5 | 186 | |
hudakz | 6:518950e436be | 187 | // Convert the raw bytes to a 16-bit unsigned value |
hudakz | 0:433af64321d5 | 188 | uint16_t* p_word = reinterpret_cast < uint16_t * > (&data[0]); |
hudakz | 0:433af64321d5 | 189 | |
hudakz | 0:433af64321d5 | 190 | #if DEBUG |
hudakz | 17:9ff584b9809f | 191 | printf("raw = %#x\r\n", *p_word); |
hudakz | 0:433af64321d5 | 192 | #endif |
hudakz | 0:433af64321d5 | 193 | |
hudakz | 8:8dfdd1603e4d | 194 | if(model_s) { |
hudakz | 6:518950e436be | 195 | *p_word = *p_word << 3; // 9-bit resolution |
hudakz | 0:433af64321d5 | 196 | if(data[7] == 0x10) { |
hudakz | 0:433af64321d5 | 197 | |
hudakz | 6:518950e436be | 198 | // "count remain" gives full 12-bit resolution |
hudakz | 0:433af64321d5 | 199 | *p_word = (*p_word & 0xFFF0) + 12 - data[6]; |
hudakz | 0:433af64321d5 | 200 | } |
hudakz | 0:433af64321d5 | 201 | } |
hudakz | 0:433af64321d5 | 202 | else { |
hudakz | 6:518950e436be | 203 | uint8_t cfg = (data[4] & 0x60); // default 12-bit resolution |
hudakz | 4:adf4e7972d73 | 204 | |
hudakz | 4:adf4e7972d73 | 205 | // at lower resolution, the low bits are undefined, so let's clear them |
hudakz | 0:433af64321d5 | 206 | if(cfg == 0x00) |
hudakz | 6:518950e436be | 207 | *p_word = *p_word &~7; // 9-bit resolution |
hudakz | 0:433af64321d5 | 208 | else |
hudakz | 0:433af64321d5 | 209 | if(cfg == 0x20) |
hudakz | 6:518950e436be | 210 | *p_word = *p_word &~3; // 10-bit resolution |
hudakz | 0:433af64321d5 | 211 | else |
hudakz | 0:433af64321d5 | 212 | if(cfg == 0x40) |
hudakz | 6:518950e436be | 213 | *p_word = *p_word &~1; // 11-bit resolution |
hudakz | 4:adf4e7972d73 | 214 | |
hudakz | 0:433af64321d5 | 215 | } |
hudakz | 6:518950e436be | 216 | |
hudakz | 6:518950e436be | 217 | // Convert the raw bytes to a 16-bit signed fixed point value : |
hudakz | 6:518950e436be | 218 | // 1 sign bit, 7 integer bits, 8 fractional bits (two’s compliment |
hudakz | 6:518950e436be | 219 | // and the LSB of the 16-bit binary number represents 1/256th of a unit). |
hudakz | 6:518950e436be | 220 | *p_word = *p_word << 4; |
hudakz | 6:518950e436be | 221 | |
hudakz | 6:518950e436be | 222 | // Convert to floating point value |
hudakz | 6:518950e436be | 223 | return(toFloat(*p_word)); |
hudakz | 0:433af64321d5 | 224 | } |
hudakz | 0:433af64321d5 | 225 | else |
hudakz | 0:433af64321d5 | 226 | return 0; |
hudakz | 0:433af64321d5 | 227 | } |
hudakz | 0:433af64321d5 | 228 | |
hudakz | 0:433af64321d5 | 229 | /** |
hudakz | 13:b593a82ce790 | 230 | * @brief Reads temperature from chip's scratchpad. |
hudakz | 13:b593a82ce790 | 231 | * @note Verifies data integrity by calculating cyclic redundancy check (CRC). |
hudakz | 13:b593a82ce790 | 232 | * If the calculated CRC dosn't match the one stored in chip's scratchpad register |
hudakz | 13:b593a82ce790 | 233 | * the temperature variable is not updated and CRC error code is returned. |
hudakz | 13:b593a82ce790 | 234 | * @param temp: The temperature variable to be updated by this routine. |
hudakz | 13:b593a82ce790 | 235 | * (It's passed as reference to floating point.) |
hudakz | 13:b593a82ce790 | 236 | * @retval error code: |
hudakz | 13:b593a82ce790 | 237 | * 0 - no errors ('temp' contains the temperature measured) |
hudakz | 13:b593a82ce790 | 238 | * 1 - sensor not present ('temp' is not updated) |
hudakz | 13:b593a82ce790 | 239 | * 2 - CRC error ('temp' is not updated) |
hudakz | 13:b593a82ce790 | 240 | */ |
hudakz | 13:b593a82ce790 | 241 | uint8_t DS1820::read(float& temp) { |
hudakz | 13:b593a82ce790 | 242 | if(present) { |
hudakz | 20:98c261bcb399 | 243 | oneWire->reset(); |
hudakz | 20:98c261bcb399 | 244 | oneWire->select(addr); |
hudakz | 20:98c261bcb399 | 245 | oneWire->write_byte(0xBE); // to read Scratchpad |
hudakz | 17:9ff584b9809f | 246 | for(uint8_t i = 0; i < 9; i++) // reading scratchpad registers |
hudakz | 20:98c261bcb399 | 247 | data[i] = oneWire->read_byte(); |
hudakz | 13:b593a82ce790 | 248 | |
hudakz | 20:98c261bcb399 | 249 | if(oneWire->crc8(data, 8) != data[8]) // if calculated CRC does not match the stored one |
hudakz | 17:9ff584b9809f | 250 | { |
hudakz | 17:9ff584b9809f | 251 | #if DEBUG |
hudakz | 17:9ff584b9809f | 252 | for(uint8_t i = 0; i < 9; i++) |
hudakz | 17:9ff584b9809f | 253 | printf("data[%d]=0x%.2x\r\n", i, data[i]); |
hudakz | 17:9ff584b9809f | 254 | #endif |
hudakz | 13:b593a82ce790 | 255 | return 2; // return with CRC error |
hudakz | 17:9ff584b9809f | 256 | } |
hudakz | 13:b593a82ce790 | 257 | |
hudakz | 13:b593a82ce790 | 258 | // Convert the raw bytes to a 16bit unsigned value |
hudakz | 13:b593a82ce790 | 259 | uint16_t* p_word = reinterpret_cast < uint16_t * > (&data[0]); |
hudakz | 13:b593a82ce790 | 260 | |
hudakz | 13:b593a82ce790 | 261 | #if DEBUG |
hudakz | 17:9ff584b9809f | 262 | printf("raw = %#x\r\n", *p_word); |
hudakz | 13:b593a82ce790 | 263 | #endif |
hudakz | 13:b593a82ce790 | 264 | |
hudakz | 13:b593a82ce790 | 265 | if(model_s) { |
hudakz | 13:b593a82ce790 | 266 | *p_word = *p_word << 3; // 9 bit resolution, max conversion time = 750ms |
hudakz | 13:b593a82ce790 | 267 | if(data[7] == 0x10) { |
hudakz | 13:b593a82ce790 | 268 | |
hudakz | 13:b593a82ce790 | 269 | // "count remain" gives full 12 bit resolution |
hudakz | 13:b593a82ce790 | 270 | *p_word = (*p_word & 0xFFF0) + 12 - data[6]; |
hudakz | 13:b593a82ce790 | 271 | } |
hudakz | 13:b593a82ce790 | 272 | |
hudakz | 13:b593a82ce790 | 273 | // Convert the raw bytes to a 16bit signed fixed point value : |
hudakz | 13:b593a82ce790 | 274 | // 1 sign bit, 7 integer bits, 8 fractional bits (two's compliment |
hudakz | 13:b593a82ce790 | 275 | // and the LSB of the 16bit binary number represents 1/256th of a unit). |
hudakz | 13:b593a82ce790 | 276 | *p_word = *p_word << 4; |
hudakz | 13:b593a82ce790 | 277 | // Convert to floating point value |
hudakz | 13:b593a82ce790 | 278 | temp = toFloat(*p_word); |
hudakz | 13:b593a82ce790 | 279 | return 0; // return with no errors |
hudakz | 13:b593a82ce790 | 280 | } |
hudakz | 13:b593a82ce790 | 281 | else { |
hudakz | 13:b593a82ce790 | 282 | uint8_t cfg = (data[4] & 0x60); // default 12bit resolution, max conversion time = 750ms |
hudakz | 13:b593a82ce790 | 283 | |
hudakz | 13:b593a82ce790 | 284 | // at lower resolution, the low bits are undefined, so let's clear them |
hudakz | 13:b593a82ce790 | 285 | if(cfg == 0x00) |
hudakz | 13:b593a82ce790 | 286 | *p_word = *p_word &~7; // 9bit resolution, max conversion time = 93.75ms |
hudakz | 13:b593a82ce790 | 287 | else |
hudakz | 13:b593a82ce790 | 288 | if(cfg == 0x20) |
hudakz | 13:b593a82ce790 | 289 | *p_word = *p_word &~3; // 10bit resolution, max conversion time = 187.5ms |
hudakz | 13:b593a82ce790 | 290 | else |
hudakz | 13:b593a82ce790 | 291 | if(cfg == 0x40) |
hudakz | 13:b593a82ce790 | 292 | *p_word = *p_word &~1; // 11bit resolution, max conversion time = 375ms |
hudakz | 13:b593a82ce790 | 293 | |
hudakz | 13:b593a82ce790 | 294 | // Convert the raw bytes to a 16bit signed fixed point value : |
hudakz | 14:b02fa18b294a | 295 | // 1 sign bit, 7 integer bits, 8 fractional bits (two's complement |
hudakz | 13:b593a82ce790 | 296 | // and the LSB of the 16bit binary number represents 1/256th of a unit). |
hudakz | 13:b593a82ce790 | 297 | *p_word = *p_word << 4; |
hudakz | 13:b593a82ce790 | 298 | // Convert to floating point value |
hudakz | 13:b593a82ce790 | 299 | temp = toFloat(*p_word); |
hudakz | 13:b593a82ce790 | 300 | return 0; // return with no errors |
hudakz | 13:b593a82ce790 | 301 | } |
hudakz | 13:b593a82ce790 | 302 | } |
hudakz | 13:b593a82ce790 | 303 | else |
hudakz | 13:b593a82ce790 | 304 | return 1; // error, sensor is not present |
hudakz | 13:b593a82ce790 | 305 | } |
hudakz | 13:b593a82ce790 | 306 | |
hudakz | 13:b593a82ce790 | 307 | /** |
hudakz | 6:518950e436be | 308 | * @brief Converts a 16-bit signed fixed point value to floating point value |
hudakz | 6:518950e436be | 309 | * @note The 16-bit unsigned integer represnts actually |
hudakz | 6:518950e436be | 310 | * a 16-bit signed fixed point value: |
hudakz | 14:b02fa18b294a | 311 | * 1 sign bit, 7 integer bits, 8 fractional bits (two’s complement |
hudakz | 6:518950e436be | 312 | * and the LSB of the 16-bit binary number represents 1/256th of a unit). |
hudakz | 6:518950e436be | 313 | * @param 16-bit unsigned integer |
hudakz | 4:adf4e7972d73 | 314 | * @retval Floating point value |
hudakz | 0:433af64321d5 | 315 | */ |
hudakz | 0:433af64321d5 | 316 | float DS1820::toFloat(uint16_t word) { |
hudakz | 0:433af64321d5 | 317 | if(word & 0x8000) |
hudakz | 0:433af64321d5 | 318 | return (-float(uint16_t(~word + 1)) / 256.0f); |
hudakz | 0:433af64321d5 | 319 | else |
hudakz | 0:433af64321d5 | 320 | return (float(word) / 256.0f); |
hudakz | 0:433af64321d5 | 321 | } |
hudakz | 0:433af64321d5 | 322 |