Erik Hatfield / DS1820

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Fork of DS1820 by Zoltan Hudak

DS1820.cpp@2:b7ad1da7331a, 2015-03-16 (annotated)

Committer:
hudakz
Date:
Mon Mar 16 08:52:33 2015 +0000
Revision:
2:b7ad1da7331a
Parent:
1:e4689408d617
Child:
3:a250babd0a9f
Bug fix

Who changed what in which revision?

UserRevisionLine numberNew contents of line
hudakz 0:433af64321d5 1 #include "DS1820.h"
hudakz 0:433af64321d5 2
hudakz 1:e4689408d617 3 #define DEBUG 0
hudakz 0:433af64321d5 4
hudakz 0:433af64321d5 5 #if DEBUG
hudakz 0:433af64321d5 6 extern Serial serial;
hudakz 0:433af64321d5 7 #endif
hudakz 0:433af64321d5 8
hudakz 0:433af64321d5 9 /**
hudakz 0:433af64321d5 10 * @brief Constructs a generic DS1820 sensor
hudakz 0:433af64321d5 11 * @note begin() must be called to detect and initialize the actual model
hudakz 0:433af64321d5 12 * @param Name of data pin
hudakz 0:433af64321d5 13 * @retval
hudakz 0:433af64321d5 14 */
hudakz 0:433af64321d5 15 DS1820::DS1820(PinName pin) :
hudakz 0:433af64321d5 16 oneWire(pin) {
hudakz 0:433af64321d5 17 present = 0;
hudakz 0:433af64321d5 18 type_s = 0;
hudakz 0:433af64321d5 19 }
hudakz 0:433af64321d5 20
hudakz 0:433af64321d5 21 /**
hudakz 0:433af64321d5 22 * @brief Constructs a specific model
hudakz 0:433af64321d5 23 * @note No need to call begin() to detect and initialize the model
hudakz 0:433af64321d5 24 * @param One character model name: 'S', 's', 'B' or 'b'
hudakz 0:433af64321d5 25 * Name of data pin
hudakz 0:433af64321d5 26 * @retval
hudakz 0:433af64321d5 27 */
hudakz 0:433af64321d5 28 DS1820::DS1820(char model, PinName pin) :
hudakz 0:433af64321d5 29 oneWire(pin) {
hudakz 0:433af64321d5 30 if((model == 'S') or (model == 's')) {
hudakz 0:433af64321d5 31 present = 1;
hudakz 0:433af64321d5 32 type_s = 1;
hudakz 0:433af64321d5 33 }
hudakz 0:433af64321d5 34 else if((model == 'B') or (model == 'b')) {
hudakz 0:433af64321d5 35 present = 1;
hudakz 0:433af64321d5 36 type_s = 0;
hudakz 0:433af64321d5 37 }
hudakz 0:433af64321d5 38 else
hudakz 0:433af64321d5 39 present = 0;
hudakz 0:433af64321d5 40 }
hudakz 0:433af64321d5 41
hudakz 0:433af64321d5 42 /**
hudakz 0:433af64321d5 43 * @brief Detects and initializes the actual DS1820 model
hudakz 0:433af64321d5 44 * @note
hudakz 0:433af64321d5 45 * @param
hudakz 0:433af64321d5 46 * @retval true: if a DS1820 family sensor was detected and initialized
hudakz 0:433af64321d5 47 false: otherwise
hudakz 0:433af64321d5 48 */
hudakz 0:433af64321d5 49 bool DS1820::begin(void) {
hudakz 0:433af64321d5 50 oneWire.reset_search();
hudakz 0:433af64321d5 51 wait_ms(250);
hudakz 0:433af64321d5 52 if(!oneWire.search(addr)) {
hudakz 0:433af64321d5 53 #if DEBUG
hudakz 0:433af64321d5 54 serial.printf("No addresses.\r\n");
hudakz 0:433af64321d5 55 #endif
hudakz 0:433af64321d5 56 oneWire.reset_search();
hudakz 0:433af64321d5 57 wait_ms(250);
hudakz 0:433af64321d5 58 return false;
hudakz 0:433af64321d5 59 }
hudakz 0:433af64321d5 60
hudakz 0:433af64321d5 61 #if DEBUG
hudakz 0:433af64321d5 62 serial.printf("ROM =");
hudakz 0:433af64321d5 63 for(uint8_t i = 0; i < 8; i++) {
hudakz 0:433af64321d5 64 serial.printf(" %x", addr[i]);
hudakz 0:433af64321d5 65 }
hudakz 0:433af64321d5 66 serial.printf("\r\n");
hudakz 0:433af64321d5 67 #endif
hudakz 0:433af64321d5 68
hudakz 0:433af64321d5 69 if(OneWire::crc8(addr, 7) == addr[7]) {
hudakz 0:433af64321d5 70 present = 1;
hudakz 0:433af64321d5 71
hudakz 0:433af64321d5 72 // the first ROM byte indicates which chip
hudakz 0:433af64321d5 73 switch(addr[0]) {
hudakz 0:433af64321d5 74 case 0x10:
hudakz 0:433af64321d5 75 type_s = 1;
hudakz 0:433af64321d5 76 #if DEBUG
hudakz 0:433af64321d5 77 serial.printf("DS18S20 or old DS1820\r\n");
hudakz 0:433af64321d5 78 #endif
hudakz 0:433af64321d5 79 break;
hudakz 0:433af64321d5 80
hudakz 0:433af64321d5 81 case 0x28:
hudakz 0:433af64321d5 82 type_s = 0;
hudakz 0:433af64321d5 83 #if DEBUG
hudakz 0:433af64321d5 84 serial.printf("DS18B20\r\n");
hudakz 0:433af64321d5 85 #endif
hudakz 0:433af64321d5 86 break;
hudakz 0:433af64321d5 87
hudakz 0:433af64321d5 88 case 0x22:
hudakz 0:433af64321d5 89 type_s = 0;
hudakz 0:433af64321d5 90 #if DEBUG
hudakz 0:433af64321d5 91 serial.printf("DS1822\r\n");
hudakz 0:433af64321d5 92 #endif
hudakz 0:433af64321d5 93 break;
hudakz 0:433af64321d5 94
hudakz 0:433af64321d5 95 default:
hudakz 0:433af64321d5 96 present = 0;
hudakz 0:433af64321d5 97 #if DEBUG
hudakz 0:433af64321d5 98 serial.printf("Device doesn't belong to the DS1820 family\r\n");
hudakz 2:b7ad1da7331a 99 #endif
hudakz 0:433af64321d5 100 return false;
hudakz 0:433af64321d5 101 }
hudakz 0:433af64321d5 102 return true;
hudakz 0:433af64321d5 103 }
hudakz 2:b7ad1da7331a 104 else {
hudakz 0:433af64321d5 105 #if DEBUG
hudakz 0:433af64321d5 106 serial.printf("Invalid CRC!\r\n");
hudakz 2:b7ad1da7331a 107 #endif
hudakz 0:433af64321d5 108 return false;
hudakz 0:433af64321d5 109 }
hudakz 0:433af64321d5 110 }
hudakz 0:433af64321d5 111
hudakz 0:433af64321d5 112 /**
hudakz 0:433af64321d5 113 * @brief Starts temperature conversion
hudakz 0:433af64321d5 114 * @note The time to complete the converion depends on the selected resolusion
hudakz 0:433af64321d5 115 * @param
hudakz 0:433af64321d5 116 * @retval
hudakz 0:433af64321d5 117 */
hudakz 0:433af64321d5 118 void DS1820::startConversion(void) {
hudakz 0:433af64321d5 119 if(present) {
hudakz 0:433af64321d5 120 oneWire.reset();
hudakz 0:433af64321d5 121
hudakz 0:433af64321d5 122 //oneWire.select(addr);
hudakz 0:433af64321d5 123 oneWire.skip();
hudakz 0:433af64321d5 124 oneWire.write(0x44); //start conversion
hudakz 0:433af64321d5 125 }
hudakz 0:433af64321d5 126 }
hudakz 0:433af64321d5 127
hudakz 0:433af64321d5 128 /**
hudakz 0:433af64321d5 129 * @brief Reads temperature from the chip's scratchpad
hudakz 0:433af64321d5 130 * @note
hudakz 0:433af64321d5 131 * @param
hudakz 0:433af64321d5 132 * @retval Floating point temperature value
hudakz 0:433af64321d5 133 */
hudakz 0:433af64321d5 134 float DS1820::read(void) {
hudakz 0:433af64321d5 135 if(present) {
hudakz 0:433af64321d5 136 oneWire.reset();
hudakz 0:433af64321d5 137 oneWire.skip();
hudakz 0:433af64321d5 138 oneWire.write(0xBE); // to read Scratchpad
hudakz 0:433af64321d5 139 for(uint8_t i = 0; i < 9; i++)
hudakz 0:433af64321d5 140 data[i] = oneWire.read();
hudakz 0:433af64321d5 141
hudakz 0:433af64321d5 142 // Convert the raw bytes to a 16bit signed fixed point value :
hudakz 0:433af64321d5 143 // 1 sign bit, 7 integer bits, 8 fractional bits (two’s compliment
hudakz 0:433af64321d5 144 // ie. the LSB of the 16bit binary number represents 1/256th of a unit).
hudakz 0:433af64321d5 145
hudakz 0:433af64321d5 146 uint16_t* p_word = reinterpret_cast < uint16_t * > (&data[0]);
hudakz 0:433af64321d5 147
hudakz 0:433af64321d5 148 #if DEBUG
hudakz 0:433af64321d5 149 serial.printf("raw = %#x\r\n", *p_word);
hudakz 0:433af64321d5 150 #endif
hudakz 0:433af64321d5 151
hudakz 0:433af64321d5 152
hudakz 0:433af64321d5 153 if(type_s) {
hudakz 0:433af64321d5 154 *p_word = *p_word << 3; // default 9 bit resolution
hudakz 0:433af64321d5 155 if(data[7] == 0x10) {
hudakz 0:433af64321d5 156
hudakz 0:433af64321d5 157 // "count remain" gives full 12 bit resolution
hudakz 0:433af64321d5 158 *p_word = (*p_word & 0xFFF0) + 12 - data[6];
hudakz 0:433af64321d5 159 }
hudakz 0:433af64321d5 160
hudakz 0:433af64321d5 161 *p_word = *p_word << 4;
hudakz 0:433af64321d5 162 return(toFloat(*p_word));
hudakz 0:433af64321d5 163 }
hudakz 0:433af64321d5 164 else {
hudakz 0:433af64321d5 165 uint8_t cfg = (data[4] & 0x60);
hudakz 0:433af64321d5 166 // at lower res, the low bits are undefined, so let's zero them
hudakz 0:433af64321d5 167
hudakz 0:433af64321d5 168 if(cfg == 0x00)
hudakz 0:433af64321d5 169 *p_word = *p_word &~7; // 9 bit resolution, 93.75 ms
hudakz 0:433af64321d5 170 else
hudakz 0:433af64321d5 171 if(cfg == 0x20)
hudakz 0:433af64321d5 172 *p_word = *p_word &~3; // 10 bit res, 187.5 ms
hudakz 0:433af64321d5 173 else
hudakz 0:433af64321d5 174 if(cfg == 0x40)
hudakz 0:433af64321d5 175 *p_word = *p_word &~1; // 11 bit res, 375 ms
hudakz 0:433af64321d5 176 *p_word = *p_word << 4; // default is 12 bit resolution
hudakz 0:433af64321d5 177 return(toFloat(*p_word));
hudakz 0:433af64321d5 178 }
hudakz 0:433af64321d5 179 }
hudakz 0:433af64321d5 180 else
hudakz 0:433af64321d5 181 return 0;
hudakz 0:433af64321d5 182 }
hudakz 0:433af64321d5 183
hudakz 0:433af64321d5 184 /**
hudakz 0:433af64321d5 185 * @brief Converts a 16bit signed fixed point value to float
hudakz 0:433af64321d5 186 * @note The 16bit unsigned integer represnts actually
hudakz 0:433af64321d5 187 * a 16bit signed fixed point value:
hudakz 0:433af64321d5 188 * 1 sign bit, 7 integer bits, 8 fractional bits
hudakz 0:433af64321d5 189 * (two’s compliment ie. the LSB of the 16bit binary number
hudakz 0:433af64321d5 190 * represents 1/256th of a unit).
hudakz 0:433af64321d5 191 * @param 16bit unsigned integer
hudakz 0:433af64321d5 192 * @retval Floating point temperature value
hudakz 0:433af64321d5 193 */
hudakz 0:433af64321d5 194 float DS1820::toFloat(uint16_t word) {
hudakz 0:433af64321d5 195 //word = word << 4;
hudakz 0:433af64321d5 196 if(word & 0x8000)
hudakz 0:433af64321d5 197 return (-float(uint16_t(~word + 1)) / 256.0f);
hudakz 0:433af64321d5 198 else
hudakz 0:433af64321d5 199 return (float(word) / 256.0f);
hudakz 0:433af64321d5 200 }
hudakz 0:433af64321d5 201