Jozsef Benecs / Mbed 2 deprecated Measure_system

Measure system

Dependencies:   EthernetNetIf mbed RF12B

DS1820/DS1820.cpp@0:8d62137f7ff4, 2011-03-03 (annotated)

Committer:
benecsj
Date:
Thu Mar 03 08:45:49 2011 +0000
Revision:
0:8d62137f7ff4
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Who changed what in which revision?

UserRevisionLine numberNew contents of line
benecsj 0:8d62137f7ff4 1 #include "DS1820.h"
benecsj 0:8d62137f7ff4 2 #include "mbed.h"
benecsj 0:8d62137f7ff4 3
benecsj 0:8d62137f7ff4 4 // Global variables shared between all DS1820 objects
benecsj 0:8d62137f7ff4 5 bool DS1820_done_flag;
benecsj 0:8d62137f7ff4 6 int DS1820_last_descrepancy;
benecsj 0:8d62137f7ff4 7 char DS1820_search_ROM[8];
benecsj 0:8d62137f7ff4 8
benecsj 0:8d62137f7ff4 9
benecsj 0:8d62137f7ff4 10 DS1820::DS1820 (PinName data_pin, PinName power_pin) : _datapin(data_pin), _parasitepin(power_pin) {
benecsj 0:8d62137f7ff4 11 int byte_counter;
benecsj 0:8d62137f7ff4 12 _parasite_power = true;
benecsj 0:8d62137f7ff4 13 for(byte_counter=0;byte_counter<8;byte_counter++)
benecsj 0:8d62137f7ff4 14 ROM[byte_counter] = 0xFF;
benecsj 0:8d62137f7ff4 15 for(byte_counter=0;byte_counter<9;byte_counter++)
benecsj 0:8d62137f7ff4 16 RAM[byte_counter] = 0x00;
benecsj 0:8d62137f7ff4 17 }
benecsj 0:8d62137f7ff4 18 DS1820::DS1820 (PinName data_pin) : _datapin(data_pin), _parasitepin(NC) {
benecsj 0:8d62137f7ff4 19 int byte_counter;
benecsj 0:8d62137f7ff4 20 _parasite_power = false;
benecsj 0:8d62137f7ff4 21 for(byte_counter=0;byte_counter<8;byte_counter++)
benecsj 0:8d62137f7ff4 22 ROM[byte_counter] = 0xFF;
benecsj 0:8d62137f7ff4 23 for(byte_counter=0;byte_counter<9;byte_counter++)
benecsj 0:8d62137f7ff4 24 RAM[byte_counter] = 0x00;
benecsj 0:8d62137f7ff4 25 }
benecsj 0:8d62137f7ff4 26
benecsj 0:8d62137f7ff4 27 bool DS1820::onewire_reset() {
benecsj 0:8d62137f7ff4 28 // This will return false if no devices are present on the data bus
benecsj 0:8d62137f7ff4 29 bool presence=false;
benecsj 0:8d62137f7ff4 30 _datapin.output();
benecsj 0:8d62137f7ff4 31 _datapin = 0; // bring low for 500 us
benecsj 0:8d62137f7ff4 32 wait_us(500);
benecsj 0:8d62137f7ff4 33 _datapin.input(); // let the data line float high
benecsj 0:8d62137f7ff4 34 wait_us(90); // wait 90us
benecsj 0:8d62137f7ff4 35 if (_datapin.read()==0) // see if any devices are pulling the data line low
benecsj 0:8d62137f7ff4 36 presence=true;
benecsj 0:8d62137f7ff4 37 wait_us(410);
benecsj 0:8d62137f7ff4 38 return presence;
benecsj 0:8d62137f7ff4 39 }
benecsj 0:8d62137f7ff4 40
benecsj 0:8d62137f7ff4 41 void DS1820::onewire_bit_out (bool bit_data) {
benecsj 0:8d62137f7ff4 42 _datapin.output();
benecsj 0:8d62137f7ff4 43 _datapin = 0;
benecsj 0:8d62137f7ff4 44 wait_us(5);
benecsj 0:8d62137f7ff4 45 if (bit_data) {
benecsj 0:8d62137f7ff4 46 _datapin.input(); // bring data line high
benecsj 0:8d62137f7ff4 47 wait_us(55);
benecsj 0:8d62137f7ff4 48 } else {
benecsj 0:8d62137f7ff4 49 wait_us(55); // keep data line low
benecsj 0:8d62137f7ff4 50 _datapin.input();
benecsj 0:8d62137f7ff4 51 }
benecsj 0:8d62137f7ff4 52 }
benecsj 0:8d62137f7ff4 53
benecsj 0:8d62137f7ff4 54 void DS1820::onewire_byte_out(char data) { // output data character (least sig bit first).
benecsj 0:8d62137f7ff4 55 int n;
benecsj 0:8d62137f7ff4 56 for (n=0; n<8; n++) {
benecsj 0:8d62137f7ff4 57 onewire_bit_out(data & 0x01);
benecsj 0:8d62137f7ff4 58 data = data >> 1; // now the next bit is in the least sig bit position.
benecsj 0:8d62137f7ff4 59 }
benecsj 0:8d62137f7ff4 60 }
benecsj 0:8d62137f7ff4 61
benecsj 0:8d62137f7ff4 62 bool DS1820::onewire_bit_in() {
benecsj 0:8d62137f7ff4 63 bool answer;
benecsj 0:8d62137f7ff4 64 _datapin.output();
benecsj 0:8d62137f7ff4 65 _datapin = 0;
benecsj 0:8d62137f7ff4 66 wait_us(5);
benecsj 0:8d62137f7ff4 67 _datapin.input();
benecsj 0:8d62137f7ff4 68 wait_us(5);
benecsj 0:8d62137f7ff4 69 answer = _datapin.read();
benecsj 0:8d62137f7ff4 70 wait_us(50);
benecsj 0:8d62137f7ff4 71 return answer;
benecsj 0:8d62137f7ff4 72 }
benecsj 0:8d62137f7ff4 73
benecsj 0:8d62137f7ff4 74 char DS1820::onewire_byte_in() { // read byte, least sig byte first
benecsj 0:8d62137f7ff4 75 char answer = 0x00;
benecsj 0:8d62137f7ff4 76 int i;
benecsj 0:8d62137f7ff4 77 for (i=0; i<8; i++) {
benecsj 0:8d62137f7ff4 78 answer = answer >> 1; // shift over to make room for the next bit
benecsj 0:8d62137f7ff4 79 if (onewire_bit_in())
benecsj 0:8d62137f7ff4 80 answer = answer | 0x80; // if the data port is high, make this bit a 1
benecsj 0:8d62137f7ff4 81 }
benecsj 0:8d62137f7ff4 82 return answer;
benecsj 0:8d62137f7ff4 83 }
benecsj 0:8d62137f7ff4 84
benecsj 0:8d62137f7ff4 85 bool DS1820::search_ROM() {
benecsj 0:8d62137f7ff4 86 return search_ROM_routine(0xF0); // Search ROM command
benecsj 0:8d62137f7ff4 87 }
benecsj 0:8d62137f7ff4 88
benecsj 0:8d62137f7ff4 89 bool DS1820::search_alarm() {
benecsj 0:8d62137f7ff4 90 return search_ROM_routine(0xEC); // Search Alarm command
benecsj 0:8d62137f7ff4 91 }
benecsj 0:8d62137f7ff4 92
benecsj 0:8d62137f7ff4 93 bool DS1820::search_ROM_routine(char command) {
benecsj 0:8d62137f7ff4 94 extern bool DS1820_done_flag;
benecsj 0:8d62137f7ff4 95 extern int DS1820_last_descrepancy;
benecsj 0:8d62137f7ff4 96 extern char DS1820_search_ROM[8];
benecsj 0:8d62137f7ff4 97 int descrepancy_marker, ROM_bit_index;
benecsj 0:8d62137f7ff4 98 bool return_value, Bit_A, Bit_B;
benecsj 0:8d62137f7ff4 99 char byte_counter, bit_mask;
benecsj 0:8d62137f7ff4 100
benecsj 0:8d62137f7ff4 101 return_value=false;
benecsj 0:8d62137f7ff4 102 if (!DS1820_done_flag) {
benecsj 0:8d62137f7ff4 103 if (!onewire_reset()) {
benecsj 0:8d62137f7ff4 104 DS1820_last_descrepancy = 0; // no devices present
benecsj 0:8d62137f7ff4 105 } else {
benecsj 0:8d62137f7ff4 106 ROM_bit_index=1;
benecsj 0:8d62137f7ff4 107 descrepancy_marker=0;
benecsj 0:8d62137f7ff4 108 onewire_byte_out(command); // Search ROM command or Search Alarm command
benecsj 0:8d62137f7ff4 109 byte_counter = 0;
benecsj 0:8d62137f7ff4 110 bit_mask = 0x01;
benecsj 0:8d62137f7ff4 111 while (ROM_bit_index<=64) {
benecsj 0:8d62137f7ff4 112 Bit_A = onewire_bit_in();
benecsj 0:8d62137f7ff4 113 Bit_B = onewire_bit_in();
benecsj 0:8d62137f7ff4 114 if (Bit_A & Bit_B) {
benecsj 0:8d62137f7ff4 115 descrepancy_marker = 0; // data read error, this should never happen
benecsj 0:8d62137f7ff4 116 ROM_bit_index = 0xFF;
benecsj 0:8d62137f7ff4 117 } else {
benecsj 0:8d62137f7ff4 118 if (Bit_A | Bit_B) {
benecsj 0:8d62137f7ff4 119 // Set ROM bit to Bit_A
benecsj 0:8d62137f7ff4 120 if (Bit_A) {
benecsj 0:8d62137f7ff4 121 DS1820_search_ROM[byte_counter] = DS1820_search_ROM[byte_counter] | bit_mask; // Set ROM bit to one
benecsj 0:8d62137f7ff4 122 } else {
benecsj 0:8d62137f7ff4 123 DS1820_search_ROM[byte_counter] = DS1820_search_ROM[byte_counter] & ~bit_mask; // Set ROM bit to zero
benecsj 0:8d62137f7ff4 124 }
benecsj 0:8d62137f7ff4 125 } else {
benecsj 0:8d62137f7ff4 126 // both bits A and B are low, so there are two or more devices present
benecsj 0:8d62137f7ff4 127 if ( ROM_bit_index == DS1820_last_descrepancy ) {
benecsj 0:8d62137f7ff4 128 DS1820_search_ROM[byte_counter] = DS1820_search_ROM[byte_counter] | bit_mask; // Set ROM bit to one
benecsj 0:8d62137f7ff4 129 } else {
benecsj 0:8d62137f7ff4 130 if ( ROM_bit_index > DS1820_last_descrepancy ) {
benecsj 0:8d62137f7ff4 131 DS1820_search_ROM[byte_counter] = DS1820_search_ROM[byte_counter] & ~bit_mask; // Set ROM bit to zero
benecsj 0:8d62137f7ff4 132 descrepancy_marker = ROM_bit_index;
benecsj 0:8d62137f7ff4 133 } else {
benecsj 0:8d62137f7ff4 134 if (( DS1820_search_ROM[byte_counter] & bit_mask) == 0x00 )
benecsj 0:8d62137f7ff4 135 descrepancy_marker = ROM_bit_index;
benecsj 0:8d62137f7ff4 136 }
benecsj 0:8d62137f7ff4 137 }
benecsj 0:8d62137f7ff4 138 }
benecsj 0:8d62137f7ff4 139 onewire_bit_out (DS1820_search_ROM[byte_counter] & bit_mask);
benecsj 0:8d62137f7ff4 140 ROM_bit_index++;
benecsj 0:8d62137f7ff4 141 if (bit_mask & 0x80) {
benecsj 0:8d62137f7ff4 142 byte_counter++;
benecsj 0:8d62137f7ff4 143 bit_mask = 0x01;
benecsj 0:8d62137f7ff4 144 } else {
benecsj 0:8d62137f7ff4 145 bit_mask = bit_mask << 1;
benecsj 0:8d62137f7ff4 146 }
benecsj 0:8d62137f7ff4 147 }
benecsj 0:8d62137f7ff4 148 }
benecsj 0:8d62137f7ff4 149 DS1820_last_descrepancy = descrepancy_marker;
benecsj 0:8d62137f7ff4 150 if (ROM_bit_index != 0xFF) {
benecsj 0:8d62137f7ff4 151 for(byte_counter=0;byte_counter<8;byte_counter++)
benecsj 0:8d62137f7ff4 152 ROM[byte_counter] = DS1820_search_ROM[byte_counter];
benecsj 0:8d62137f7ff4 153 return_value = true;
benecsj 0:8d62137f7ff4 154 }
benecsj 0:8d62137f7ff4 155 }
benecsj 0:8d62137f7ff4 156 if (DS1820_last_descrepancy == 0)
benecsj 0:8d62137f7ff4 157 DS1820_done_flag = true;
benecsj 0:8d62137f7ff4 158 }
benecsj 0:8d62137f7ff4 159 return return_value;
benecsj 0:8d62137f7ff4 160 }
benecsj 0:8d62137f7ff4 161
benecsj 0:8d62137f7ff4 162 void DS1820::search_ROM_setup() {
benecsj 0:8d62137f7ff4 163 extern bool DS1820_done_flag;
benecsj 0:8d62137f7ff4 164 extern int DS1820_last_descrepancy;
benecsj 0:8d62137f7ff4 165 extern char DS1820_search_ROM[8];
benecsj 0:8d62137f7ff4 166 DS1820_done_flag = false;
benecsj 0:8d62137f7ff4 167 DS1820_last_descrepancy = 0;
benecsj 0:8d62137f7ff4 168 int i;
benecsj 0:8d62137f7ff4 169 for (i=0; i<8; i++)
benecsj 0:8d62137f7ff4 170 DS1820_search_ROM[i]=0x00;
benecsj 0:8d62137f7ff4 171 }
benecsj 0:8d62137f7ff4 172
benecsj 0:8d62137f7ff4 173 void DS1820::read_ROM() {
benecsj 0:8d62137f7ff4 174 // NOTE: This command can only be used when there is one DS1820 on the bus. If this command
benecsj 0:8d62137f7ff4 175 // is used when there is more than one slave present on the bus, a data collision will occur
benecsj 0:8d62137f7ff4 176 // when all the DS1820s attempt to respond at the same time.
benecsj 0:8d62137f7ff4 177 int i;
benecsj 0:8d62137f7ff4 178 onewire_reset();
benecsj 0:8d62137f7ff4 179 onewire_byte_out(0x33); // Read ROM id
benecsj 0:8d62137f7ff4 180 for (i=0; i<8; i++)
benecsj 0:8d62137f7ff4 181 ROM[i]=onewire_byte_in();
benecsj 0:8d62137f7ff4 182 }
benecsj 0:8d62137f7ff4 183
benecsj 0:8d62137f7ff4 184 void DS1820::match_ROM() {
benecsj 0:8d62137f7ff4 185 // Used to select a specific device
benecsj 0:8d62137f7ff4 186 int i;
benecsj 0:8d62137f7ff4 187 onewire_reset();
benecsj 0:8d62137f7ff4 188 onewire_byte_out( 0x55); //Match ROM command
benecsj 0:8d62137f7ff4 189 for (i=0;i<8;i++)
benecsj 0:8d62137f7ff4 190 onewire_byte_out(ROM[i]);
benecsj 0:8d62137f7ff4 191 }
benecsj 0:8d62137f7ff4 192
benecsj 0:8d62137f7ff4 193 void DS1820::skip_ROM() {
benecsj 0:8d62137f7ff4 194 onewire_reset();
benecsj 0:8d62137f7ff4 195 onewire_byte_out(0xCC); // Skip ROM command
benecsj 0:8d62137f7ff4 196 }
benecsj 0:8d62137f7ff4 197
benecsj 0:8d62137f7ff4 198 bool DS1820::ROM_checksum_error() {
benecsj 0:8d62137f7ff4 199 char CRC=0x00;
benecsj 0:8d62137f7ff4 200 int i;
benecsj 0:8d62137f7ff4 201 for(i=0;i<7;i++) // Only going to shift the lower 7 bytes
benecsj 0:8d62137f7ff4 202 CRC = CRC_byte(CRC, ROM[i]);
benecsj 0:8d62137f7ff4 203 // After 7 bytes CRC should equal the 8th byte (ROM CRC)
benecsj 0:8d62137f7ff4 204 return (CRC!=ROM[7]); // will return true if there is a CRC checksum error
benecsj 0:8d62137f7ff4 205 }
benecsj 0:8d62137f7ff4 206
benecsj 0:8d62137f7ff4 207 bool DS1820::RAM_checksum_error() {
benecsj 0:8d62137f7ff4 208 char CRC=0x00;
benecsj 0:8d62137f7ff4 209 int i;
benecsj 0:8d62137f7ff4 210 read_RAM();
benecsj 0:8d62137f7ff4 211 for(i=0;i<8;i++) // Only going to shift the lower 8 bytes
benecsj 0:8d62137f7ff4 212 CRC = CRC_byte(CRC, RAM[i]);
benecsj 0:8d62137f7ff4 213 // After 8 bytes CRC should equal the 9th byte (RAM CRC)
benecsj 0:8d62137f7ff4 214 return (CRC!=RAM[8]); // will return true if there is a CRC checksum error
benecsj 0:8d62137f7ff4 215 }
benecsj 0:8d62137f7ff4 216
benecsj 0:8d62137f7ff4 217 char DS1820::CRC_byte (char CRC, char byte ) {
benecsj 0:8d62137f7ff4 218 int j;
benecsj 0:8d62137f7ff4 219 for(j=0;j<8;j++) {
benecsj 0:8d62137f7ff4 220 if ((byte & 0x01 ) ^ (CRC & 0x01)) {
benecsj 0:8d62137f7ff4 221 // DATA ^ LSB CRC = 1
benecsj 0:8d62137f7ff4 222 CRC = CRC>>1;
benecsj 0:8d62137f7ff4 223 // Set the MSB to 1
benecsj 0:8d62137f7ff4 224 CRC = CRC | 0x80;
benecsj 0:8d62137f7ff4 225 // Check bit 3
benecsj 0:8d62137f7ff4 226 if (CRC & 0x04) {
benecsj 0:8d62137f7ff4 227 CRC = CRC & 0xFB; // Bit 3 is set, so clear it
benecsj 0:8d62137f7ff4 228 } else {
benecsj 0:8d62137f7ff4 229 CRC = CRC | 0x04; // Bit 3 is clear, so set it
benecsj 0:8d62137f7ff4 230 }
benecsj 0:8d62137f7ff4 231 // Check bit 4
benecsj 0:8d62137f7ff4 232 if (CRC & 0x08) {
benecsj 0:8d62137f7ff4 233 CRC = CRC & 0xF7; // Bit 4 is set, so clear it
benecsj 0:8d62137f7ff4 234 } else {
benecsj 0:8d62137f7ff4 235 CRC = CRC | 0x08; // Bit 4 is clear, so set it
benecsj 0:8d62137f7ff4 236 }
benecsj 0:8d62137f7ff4 237 } else {
benecsj 0:8d62137f7ff4 238 // DATA ^ LSB CRC = 0
benecsj 0:8d62137f7ff4 239 CRC = CRC>>1;
benecsj 0:8d62137f7ff4 240 // clear MSB
benecsj 0:8d62137f7ff4 241 CRC = CRC & 0x7F;
benecsj 0:8d62137f7ff4 242 // No need to check bits, with DATA ^ LSB CRC = 0, they will remain unchanged
benecsj 0:8d62137f7ff4 243 }
benecsj 0:8d62137f7ff4 244 byte = byte>>1;
benecsj 0:8d62137f7ff4 245 }
benecsj 0:8d62137f7ff4 246 return CRC;
benecsj 0:8d62137f7ff4 247 }
benecsj 0:8d62137f7ff4 248
benecsj 0:8d62137f7ff4 249 void DS1820::convert_temperature(devices device) {
benecsj 0:8d62137f7ff4 250 // Convert temperature into scratchpad RAM for all devices at once
benecsj 0:8d62137f7ff4 251 if (device==all_devices)
benecsj 0:8d62137f7ff4 252 skip_ROM(); // Skip ROM command, will convert for ALL devices
benecsj 0:8d62137f7ff4 253 else
benecsj 0:8d62137f7ff4 254 match_ROM();
benecsj 0:8d62137f7ff4 255 onewire_byte_out( 0x44); // perform temperature conversion
benecsj 0:8d62137f7ff4 256 if (_parasite_power)
benecsj 0:8d62137f7ff4 257 _parasitepin = 1; // Parasite power strong pullup
benecsj 0:8d62137f7ff4 258 wait_ms(750);
benecsj 0:8d62137f7ff4 259 if (_parasite_power)
benecsj 0:8d62137f7ff4 260 _parasitepin = 0;
benecsj 0:8d62137f7ff4 261 }
benecsj 0:8d62137f7ff4 262
benecsj 0:8d62137f7ff4 263 void DS1820::read_RAM() {
benecsj 0:8d62137f7ff4 264 // This will copy the DS1820's 9 bytes of RAM data
benecsj 0:8d62137f7ff4 265 // into the objects RAM array. Functions that use
benecsj 0:8d62137f7ff4 266 // RAM values will automaticly call this procedure.
benecsj 0:8d62137f7ff4 267 int i;
benecsj 0:8d62137f7ff4 268 match_ROM(); // Select this device
benecsj 0:8d62137f7ff4 269 onewire_byte_out( 0xBE); //Read Scratchpad command
benecsj 0:8d62137f7ff4 270 for(i=0;i<9;i++) {
benecsj 0:8d62137f7ff4 271 RAM[i] = onewire_byte_in();
benecsj 0:8d62137f7ff4 272 }
benecsj 0:8d62137f7ff4 273 }
benecsj 0:8d62137f7ff4 274
benecsj 0:8d62137f7ff4 275 int DS1820::read_scratchpad() {
benecsj 0:8d62137f7ff4 276 int answer;
benecsj 0:8d62137f7ff4 277 read_RAM();
benecsj 0:8d62137f7ff4 278 answer = (RAM[2]<<8) + RAM[3];
benecsj 0:8d62137f7ff4 279 return answer;
benecsj 0:8d62137f7ff4 280 }
benecsj 0:8d62137f7ff4 281
benecsj 0:8d62137f7ff4 282 void DS1820::write_scratchpad(int data) {
benecsj 0:8d62137f7ff4 283 RAM[3] = data;
benecsj 0:8d62137f7ff4 284 RAM[2] = data>>8;
benecsj 0:8d62137f7ff4 285 match_ROM();
benecsj 0:8d62137f7ff4 286 onewire_byte_out(0x4E); // Copy scratchpad into DS1820 ram memory
benecsj 0:8d62137f7ff4 287 onewire_byte_out(RAM[2]); // T(H)
benecsj 0:8d62137f7ff4 288 onewire_byte_out(RAM[3]); // T(L)
benecsj 0:8d62137f7ff4 289 }
benecsj 0:8d62137f7ff4 290
benecsj 0:8d62137f7ff4 291 void DS1820::store_scratchpad(devices device) {
benecsj 0:8d62137f7ff4 292 if (device==all_devices)
benecsj 0:8d62137f7ff4 293 skip_ROM(); // Skip ROM command, will store for ALL devices
benecsj 0:8d62137f7ff4 294 else
benecsj 0:8d62137f7ff4 295 match_ROM();
benecsj 0:8d62137f7ff4 296 onewire_byte_out(0x48); // Write scratchpad into E2 command
benecsj 0:8d62137f7ff4 297 if (_parasite_power)
benecsj 0:8d62137f7ff4 298 _parasitepin=1;
benecsj 0:8d62137f7ff4 299 wait_ms(10); // Parasite power strong pullup for 10ms
benecsj 0:8d62137f7ff4 300 if (_parasite_power)
benecsj 0:8d62137f7ff4 301 _parasitepin=0;
benecsj 0:8d62137f7ff4 302 }
benecsj 0:8d62137f7ff4 303
benecsj 0:8d62137f7ff4 304 int DS1820::recall_scratchpad(devices device) {
benecsj 0:8d62137f7ff4 305 // This copies the E2 values into the DS1820's memory.
benecsj 0:8d62137f7ff4 306 // If you specify all_devices this will return zero, otherwise
benecsj 0:8d62137f7ff4 307 // it will return the value of the scratchpad memory.
benecsj 0:8d62137f7ff4 308 int answer=0;
benecsj 0:8d62137f7ff4 309 if (device==all_devices)
benecsj 0:8d62137f7ff4 310 skip_ROM(); // Skip ROM command, will recall for ALL devices
benecsj 0:8d62137f7ff4 311 else
benecsj 0:8d62137f7ff4 312 match_ROM();
benecsj 0:8d62137f7ff4 313 onewire_byte_out(0xB8); // Recall E2 data to scratchpad command
benecsj 0:8d62137f7ff4 314 wait_ms(10); // not sure I like polling for completion
benecsj 0:8d62137f7ff4 315 // it could cause an infinite loop
benecsj 0:8d62137f7ff4 316 if (device==DS1820::this_device) {
benecsj 0:8d62137f7ff4 317 read_RAM();
benecsj 0:8d62137f7ff4 318 answer = read_scratchpad();
benecsj 0:8d62137f7ff4 319 }
benecsj 0:8d62137f7ff4 320 return answer;
benecsj 0:8d62137f7ff4 321 }
benecsj 0:8d62137f7ff4 322
benecsj 0:8d62137f7ff4 323 float DS1820::temperature(char scale) {
benecsj 0:8d62137f7ff4 324 // The data specs state that count_per_degree should be 0x10 (16), I found my devices
benecsj 0:8d62137f7ff4 325 // to have a count_per_degree of 0x4B (75). With the standard resolution of 1/2 deg C
benecsj 0:8d62137f7ff4 326 // this allowed an expanded resolution of 1/150th of a deg C. I wouldn't rely on this
benecsj 0:8d62137f7ff4 327 // being super acurate, but it does allow for a smooth display in the 1/10ths of a
benecsj 0:8d62137f7ff4 328 // deg C or F scales.
benecsj 0:8d62137f7ff4 329 float answer, remaining_count, count_per_degree;
benecsj 0:8d62137f7ff4 330 int reading;
benecsj 0:8d62137f7ff4 331 read_RAM();
benecsj 0:8d62137f7ff4 332 reading = (RAM[1] << 8) + RAM[0];
benecsj 0:8d62137f7ff4 333 if (reading & 0x8000) { // negative degrees C
benecsj 0:8d62137f7ff4 334 reading = 0-((reading ^ 0xffff) + 1); // 2's comp then convert to signed int
benecsj 0:8d62137f7ff4 335 }
benecsj 0:8d62137f7ff4 336 remaining_count = RAM[6];
benecsj 0:8d62137f7ff4 337 count_per_degree = RAM[7];
benecsj 0:8d62137f7ff4 338 answer = reading +0.0;
benecsj 0:8d62137f7ff4 339 answer = answer - 0.25 + (count_per_degree - remaining_count) / count_per_degree;
benecsj 0:8d62137f7ff4 340 if (scale=='C' or scale=='c')
benecsj 0:8d62137f7ff4 341 answer = answer / 16.0;
benecsj 0:8d62137f7ff4 342 else
benecsj 0:8d62137f7ff4 343 // Convert to deg F
benecsj 0:8d62137f7ff4 344 answer = answer * 9.0 / 10.0 + 32.0;
benecsj 0:8d62137f7ff4 345 return answer;
benecsj 0:8d62137f7ff4 346 }
benecsj 0:8d62137f7ff4 347
benecsj 0:8d62137f7ff4 348 bool DS1820::read_power_supply(devices device) {
benecsj 0:8d62137f7ff4 349 // This will return true if the device (or all devices) are Vcc powered
benecsj 0:8d62137f7ff4 350 // This will return false if the device (or ANY device) is parasite powered
benecsj 0:8d62137f7ff4 351 if (device==all_devices)
benecsj 0:8d62137f7ff4 352 skip_ROM(); // Skip ROM command, will poll for any device using parasite power
benecsj 0:8d62137f7ff4 353 else
benecsj 0:8d62137f7ff4 354 match_ROM();
benecsj 0:8d62137f7ff4 355 onewire_byte_out(0xB4); // Read power supply command
benecsj 0:8d62137f7ff4 356 return onewire_bit_in();
benecsj 0:8d62137f7ff4 357 }