Ernesto Palacios / DS1820

DS1820

Dependencies:   LinkedList

Fork of DS1820 by Erik -

DS1820.cpp@8:d87e11e8d012, 2014-07-08 (annotated)

Committer:
Sissors
Date:
Tue Jul 08 18:55:54 2014 +0000
Revision:
8:d87e11e8d012
Parent:
7:58b61681818f
Child:
9:3821ca0b7f14
Instead of open drain use CMOS output for writing. Not according to standard, but can help for long busses. And helps with parasite powered via data pin (no external mosfet)

Who changed what in which revision?

UserRevisionLine numberNew contents of line
pairmand 3:8f2b7f4940b5 1 #include "DS1820.h"
Sissors 5:2cd4928e8147 2
Sissors 5:2cd4928e8147 3 LinkedList<node> DS1820::probes;
pairmand 3:8f2b7f4940b5 4
pairmand 3:8f2b7f4940b5 5
Sissors 5:2cd4928e8147 6 DS1820::DS1820 (PinName data_pin, PinName power_pin, bool power_polarity) : _datapin(data_pin), _parasitepin(power_pin) {
pairmand 3:8f2b7f4940b5 7 int byte_counter;
Sissors 5:2cd4928e8147 8 _power_polarity = power_polarity;
Sissors 5:2cd4928e8147 9 if (power_pin != NC)
Sissors 5:2cd4928e8147 10 _power_mosfet = true;
Sissors 5:2cd4928e8147 11
pairmand 3:8f2b7f4940b5 12 for(byte_counter=0;byte_counter<9;byte_counter++)
pairmand 3:8f2b7f4940b5 13 RAM[byte_counter] = 0x00;
Sissors 5:2cd4928e8147 14
Sissors 5:2cd4928e8147 15 if (!unassignedProbe(&_datapin, _ROM))
Sissors 5:2cd4928e8147 16 error("No unassigned DS1820 found!\n");
Sissors 5:2cd4928e8147 17 else {
Sissors 5:2cd4928e8147 18 _datapin.input();
Sissors 5:2cd4928e8147 19 probes.append(this);
Sissors 5:2cd4928e8147 20 _parasite_power = !read_power_supply();
Sissors 5:2cd4928e8147 21 }
pairmand 3:8f2b7f4940b5 22 }
Sissors 5:2cd4928e8147 23
Sissors 5:2cd4928e8147 24 DS1820::~DS1820 (void) {
Sissors 5:2cd4928e8147 25 node *tmp;
Sissors 5:2cd4928e8147 26 for(int i=1; i<=probes.length(); i++)
Sissors 5:2cd4928e8147 27 {
Sissors 5:2cd4928e8147 28 tmp = probes.pop(i);
Sissors 5:2cd4928e8147 29 if (tmp->data == this)
Sissors 5:2cd4928e8147 30 probes.remove(i);
Sissors 5:2cd4928e8147 31 }
pairmand 3:8f2b7f4940b5 32 }
Sissors 5:2cd4928e8147 33
pairmand 3:8f2b7f4940b5 34
Sissors 5:2cd4928e8147 35 bool DS1820::onewire_reset(DigitalInOut *pin) {
pairmand 3:8f2b7f4940b5 36 // This will return false if no devices are present on the data bus
pairmand 3:8f2b7f4940b5 37 bool presence=false;
Sissors 5:2cd4928e8147 38 pin->output();
Sissors 5:2cd4928e8147 39 pin->write(0); // bring low for 500 us
pairmand 3:8f2b7f4940b5 40 wait_us(500);
Sissors 5:2cd4928e8147 41 pin->input(); // let the data line float high
pairmand 3:8f2b7f4940b5 42 wait_us(90); // wait 90us
Sissors 5:2cd4928e8147 43 if (pin->read()==0) // see if any devices are pulling the data line low
pairmand 3:8f2b7f4940b5 44 presence=true;
pairmand 3:8f2b7f4940b5 45 wait_us(410);
pairmand 3:8f2b7f4940b5 46 return presence;
pairmand 3:8f2b7f4940b5 47 }
pairmand 3:8f2b7f4940b5 48
Sissors 5:2cd4928e8147 49 void DS1820::onewire_bit_out (DigitalInOut *pin, bool bit_data) {
Sissors 5:2cd4928e8147 50 pin->output();
Sissors 5:2cd4928e8147 51 pin->write(0);
pairmand 3:8f2b7f4940b5 52 wait_us(3); // DXP modified from 5
pairmand 3:8f2b7f4940b5 53 if (bit_data) {
Sissors 8:d87e11e8d012 54 pin->write(1); // bring data line high
pairmand 3:8f2b7f4940b5 55 wait_us(55);
pairmand 3:8f2b7f4940b5 56 } else {
pairmand 3:8f2b7f4940b5 57 wait_us(55); // keep data line low
Sissors 8:d87e11e8d012 58 pin->write(1);
pairmand 3:8f2b7f4940b5 59 wait_us(10); // DXP added to allow bus to float high before next bit_out
pairmand 3:8f2b7f4940b5 60 }
pairmand 3:8f2b7f4940b5 61 }
pairmand 3:8f2b7f4940b5 62
pairmand 3:8f2b7f4940b5 63 void DS1820::onewire_byte_out(char data) { // output data character (least sig bit first).
pairmand 3:8f2b7f4940b5 64 int n;
pairmand 3:8f2b7f4940b5 65 for (n=0; n<8; n++) {
Sissors 5:2cd4928e8147 66 onewire_bit_out(&this->_datapin, data & 0x01);
pairmand 3:8f2b7f4940b5 67 data = data >> 1; // now the next bit is in the least sig bit position.
pairmand 3:8f2b7f4940b5 68 }
pairmand 3:8f2b7f4940b5 69 }
pairmand 3:8f2b7f4940b5 70
Sissors 5:2cd4928e8147 71 bool DS1820::onewire_bit_in(DigitalInOut *pin) {
pairmand 3:8f2b7f4940b5 72 bool answer;
Sissors 5:2cd4928e8147 73 pin->output();
Sissors 5:2cd4928e8147 74 pin->write(0);
pairmand 3:8f2b7f4940b5 75 wait_us(3); // DXP modofied from 5
Sissors 5:2cd4928e8147 76 pin->input();
pairmand 3:8f2b7f4940b5 77 wait_us(10); // DXP modified from 5
Sissors 5:2cd4928e8147 78 answer = pin->read();
pairmand 3:8f2b7f4940b5 79 wait_us(45); // DXP modified from 50
pairmand 3:8f2b7f4940b5 80 return answer;
pairmand 3:8f2b7f4940b5 81 }
pairmand 3:8f2b7f4940b5 82
pairmand 3:8f2b7f4940b5 83 char DS1820::onewire_byte_in() { // read byte, least sig byte first
pairmand 3:8f2b7f4940b5 84 char answer = 0x00;
pairmand 3:8f2b7f4940b5 85 int i;
pairmand 3:8f2b7f4940b5 86 for (i=0; i<8; i++) {
pairmand 3:8f2b7f4940b5 87 answer = answer >> 1; // shift over to make room for the next bit
Sissors 5:2cd4928e8147 88 if (onewire_bit_in(&this->_datapin))
pairmand 3:8f2b7f4940b5 89 answer = answer | 0x80; // if the data port is high, make this bit a 1
pairmand 3:8f2b7f4940b5 90 }
pairmand 3:8f2b7f4940b5 91 return answer;
pairmand 3:8f2b7f4940b5 92 }
Sissors 5:2cd4928e8147 93
Sissors 5:2cd4928e8147 94 bool DS1820::unassignedProbe(PinName pin) {
Sissors 5:2cd4928e8147 95 DigitalInOut _pin(pin);
Sissors 5:2cd4928e8147 96 char ROM_address[8];
Sissors 5:2cd4928e8147 97 return search_ROM_routine(&_pin, 0xF0, ROM_address);
pairmand 3:8f2b7f4940b5 98 }
pairmand 3:8f2b7f4940b5 99
Sissors 5:2cd4928e8147 100 bool DS1820::unassignedProbe(DigitalInOut *pin, char *ROM_address) {
Sissors 5:2cd4928e8147 101 return search_ROM_routine(pin, 0xF0, ROM_address);
pairmand 3:8f2b7f4940b5 102 }
pairmand 3:8f2b7f4940b5 103
Sissors 5:2cd4928e8147 104 bool DS1820::search_ROM_routine(DigitalInOut *pin, char command, char *ROM_address) {
Sissors 5:2cd4928e8147 105 bool DS1820_done_flag = false;
Sissors 5:2cd4928e8147 106 int DS1820_last_descrepancy = 0;
Sissors 5:2cd4928e8147 107 char DS1820_search_ROM[8] = {0, 0, 0, 0, 0, 0, 0, 0};
Sissors 5:2cd4928e8147 108
pairmand 3:8f2b7f4940b5 109 int descrepancy_marker, ROM_bit_index;
pairmand 3:8f2b7f4940b5 110 bool return_value, Bit_A, Bit_B;
pairmand 3:8f2b7f4940b5 111 char byte_counter, bit_mask;
pairmand 3:8f2b7f4940b5 112
pairmand 3:8f2b7f4940b5 113 return_value=false;
Sissors 5:2cd4928e8147 114 while (!DS1820_done_flag) {
Sissors 5:2cd4928e8147 115 if (!onewire_reset(pin)) {
Sissors 5:2cd4928e8147 116 return false;
pairmand 3:8f2b7f4940b5 117 } else {
pairmand 3:8f2b7f4940b5 118 ROM_bit_index=1;
pairmand 3:8f2b7f4940b5 119 descrepancy_marker=0;
Sissors 5:2cd4928e8147 120 for (int n=0; n<8; n++) { // Search ROM command or Search Alarm command
Sissors 5:2cd4928e8147 121 onewire_bit_out(pin, command & 0x01);
Sissors 5:2cd4928e8147 122 command = command >> 1; // now the next bit is in the least sig bit position.
Sissors 5:2cd4928e8147 123 }
pairmand 3:8f2b7f4940b5 124 byte_counter = 0;
pairmand 3:8f2b7f4940b5 125 bit_mask = 0x01;
pairmand 3:8f2b7f4940b5 126 while (ROM_bit_index<=64) {
Sissors 5:2cd4928e8147 127 Bit_A = onewire_bit_in(pin);
Sissors 5:2cd4928e8147 128 Bit_B = onewire_bit_in(pin);
pairmand 3:8f2b7f4940b5 129 if (Bit_A & Bit_B) {
pairmand 3:8f2b7f4940b5 130 descrepancy_marker = 0; // data read error, this should never happen
pairmand 3:8f2b7f4940b5 131 ROM_bit_index = 0xFF;
pairmand 3:8f2b7f4940b5 132 } else {
pairmand 3:8f2b7f4940b5 133 if (Bit_A | Bit_B) {
pairmand 3:8f2b7f4940b5 134 // Set ROM bit to Bit_A
pairmand 3:8f2b7f4940b5 135 if (Bit_A) {
pairmand 3:8f2b7f4940b5 136 DS1820_search_ROM[byte_counter] = DS1820_search_ROM[byte_counter] | bit_mask; // Set ROM bit to one
pairmand 3:8f2b7f4940b5 137 } else {
pairmand 3:8f2b7f4940b5 138 DS1820_search_ROM[byte_counter] = DS1820_search_ROM[byte_counter] & ~bit_mask; // Set ROM bit to zero
pairmand 3:8f2b7f4940b5 139 }
pairmand 3:8f2b7f4940b5 140 } else {
pairmand 3:8f2b7f4940b5 141 // both bits A and B are low, so there are two or more devices present
pairmand 3:8f2b7f4940b5 142 if ( ROM_bit_index == DS1820_last_descrepancy ) {
pairmand 3:8f2b7f4940b5 143 DS1820_search_ROM[byte_counter] = DS1820_search_ROM[byte_counter] | bit_mask; // Set ROM bit to one
pairmand 3:8f2b7f4940b5 144 } else {
pairmand 3:8f2b7f4940b5 145 if ( ROM_bit_index > DS1820_last_descrepancy ) {
pairmand 3:8f2b7f4940b5 146 DS1820_search_ROM[byte_counter] = DS1820_search_ROM[byte_counter] & ~bit_mask; // Set ROM bit to zero
pairmand 3:8f2b7f4940b5 147 descrepancy_marker = ROM_bit_index;
pairmand 3:8f2b7f4940b5 148 } else {
pairmand 3:8f2b7f4940b5 149 if (( DS1820_search_ROM[byte_counter] & bit_mask) == 0x00 )
pairmand 3:8f2b7f4940b5 150 descrepancy_marker = ROM_bit_index;
pairmand 3:8f2b7f4940b5 151 }
pairmand 3:8f2b7f4940b5 152 }
pairmand 3:8f2b7f4940b5 153 }
Sissors 5:2cd4928e8147 154 onewire_bit_out (pin, DS1820_search_ROM[byte_counter] & bit_mask);
pairmand 3:8f2b7f4940b5 155 ROM_bit_index++;
pairmand 3:8f2b7f4940b5 156 if (bit_mask & 0x80) {
pairmand 3:8f2b7f4940b5 157 byte_counter++;
pairmand 3:8f2b7f4940b5 158 bit_mask = 0x01;
pairmand 3:8f2b7f4940b5 159 } else {
pairmand 3:8f2b7f4940b5 160 bit_mask = bit_mask << 1;
pairmand 3:8f2b7f4940b5 161 }
pairmand 3:8f2b7f4940b5 162 }
pairmand 3:8f2b7f4940b5 163 }
pairmand 3:8f2b7f4940b5 164 DS1820_last_descrepancy = descrepancy_marker;
pairmand 3:8f2b7f4940b5 165 if (ROM_bit_index != 0xFF) {
Sissors 5:2cd4928e8147 166 int i = 1;
Sissors 5:2cd4928e8147 167 node *list_container;
Sissors 5:2cd4928e8147 168 while(1) {
Sissors 5:2cd4928e8147 169 list_container = probes.pop(i);
Sissors 5:2cd4928e8147 170 if (list_container == NULL) { //End of list, or empty list
Sissors 5:2cd4928e8147 171 if (ROM_checksum_error(DS1820_search_ROM)) { // Check the CRC
Sissors 5:2cd4928e8147 172 return false;
Sissors 5:2cd4928e8147 173 }
Sissors 5:2cd4928e8147 174 for(byte_counter=0;byte_counter<8;byte_counter++)
Sissors 5:2cd4928e8147 175 ROM_address[byte_counter] = DS1820_search_ROM[byte_counter];
Sissors 5:2cd4928e8147 176 return true;
Sissors 5:2cd4928e8147 177 } else { //Otherwise, check if ROM is already known
Sissors 5:2cd4928e8147 178 bool equal = true;
Sissors 5:2cd4928e8147 179 DS1820 *pointer = (DS1820*) list_container->data;
Sissors 5:2cd4928e8147 180 char *ROM_compare = pointer->_ROM;
Sissors 5:2cd4928e8147 181
Sissors 5:2cd4928e8147 182 for(byte_counter=0;byte_counter<8;byte_counter++) {
Sissors 5:2cd4928e8147 183 if ( ROM_compare[byte_counter] != DS1820_search_ROM[byte_counter])
Sissors 5:2cd4928e8147 184 equal = false;
Sissors 5:2cd4928e8147 185 }
Sissors 5:2cd4928e8147 186 if (equal)
Sissors 5:2cd4928e8147 187 break;
Sissors 5:2cd4928e8147 188 else
Sissors 5:2cd4928e8147 189 i++;
Sissors 5:2cd4928e8147 190 }
Sissors 5:2cd4928e8147 191 }
pairmand 3:8f2b7f4940b5 192 }
pairmand 3:8f2b7f4940b5 193 }
pairmand 3:8f2b7f4940b5 194 if (DS1820_last_descrepancy == 0)
pairmand 3:8f2b7f4940b5 195 DS1820_done_flag = true;
pairmand 3:8f2b7f4940b5 196 }
pairmand 3:8f2b7f4940b5 197 return return_value;
pairmand 3:8f2b7f4940b5 198 }
pairmand 3:8f2b7f4940b5 199
pairmand 3:8f2b7f4940b5 200 void DS1820::match_ROM() {
pairmand 3:8f2b7f4940b5 201 // Used to select a specific device
pairmand 3:8f2b7f4940b5 202 int i;
Sissors 5:2cd4928e8147 203 onewire_reset(&this->_datapin);
pairmand 3:8f2b7f4940b5 204 onewire_byte_out( 0x55); //Match ROM command
Sissors 5:2cd4928e8147 205 for (i=0;i<8;i++) {
Sissors 5:2cd4928e8147 206 onewire_byte_out(_ROM[i]);
Sissors 5:2cd4928e8147 207 }
pairmand 3:8f2b7f4940b5 208 }
pairmand 3:8f2b7f4940b5 209
pairmand 3:8f2b7f4940b5 210 void DS1820::skip_ROM() {
Sissors 5:2cd4928e8147 211 onewire_reset(&this->_datapin);
pairmand 3:8f2b7f4940b5 212 onewire_byte_out(0xCC); // Skip ROM command
pairmand 3:8f2b7f4940b5 213 }
pairmand 3:8f2b7f4940b5 214
Sissors 5:2cd4928e8147 215 bool DS1820::ROM_checksum_error(char *_ROM_address) {
pairmand 3:8f2b7f4940b5 216 char CRC=0x00;
pairmand 3:8f2b7f4940b5 217 int i;
pairmand 3:8f2b7f4940b5 218 for(i=0;i<7;i++) // Only going to shift the lower 7 bytes
Sissors 5:2cd4928e8147 219 CRC = CRC_byte(CRC, _ROM_address[i]);
pairmand 3:8f2b7f4940b5 220 // After 7 bytes CRC should equal the 8th byte (ROM CRC)
Sissors 5:2cd4928e8147 221 return (CRC!=_ROM_address[7]); // will return true if there is a CRC checksum mis-match
pairmand 3:8f2b7f4940b5 222 }
pairmand 3:8f2b7f4940b5 223
pairmand 3:8f2b7f4940b5 224 bool DS1820::RAM_checksum_error() {
pairmand 3:8f2b7f4940b5 225 char CRC=0x00;
pairmand 3:8f2b7f4940b5 226 int i;
pairmand 3:8f2b7f4940b5 227 for(i=0;i<8;i++) // Only going to shift the lower 8 bytes
pairmand 3:8f2b7f4940b5 228 CRC = CRC_byte(CRC, RAM[i]);
pairmand 3:8f2b7f4940b5 229 // After 8 bytes CRC should equal the 9th byte (RAM CRC)
pairmand 3:8f2b7f4940b5 230 return (CRC!=RAM[8]); // will return true if there is a CRC checksum mis-match
pairmand 3:8f2b7f4940b5 231 }
pairmand 3:8f2b7f4940b5 232
pairmand 3:8f2b7f4940b5 233 char DS1820::CRC_byte (char CRC, char byte ) {
pairmand 3:8f2b7f4940b5 234 int j;
pairmand 3:8f2b7f4940b5 235 for(j=0;j<8;j++) {
pairmand 3:8f2b7f4940b5 236 if ((byte & 0x01 ) ^ (CRC & 0x01)) {
pairmand 3:8f2b7f4940b5 237 // DATA ^ LSB CRC = 1
pairmand 3:8f2b7f4940b5 238 CRC = CRC>>1;
pairmand 3:8f2b7f4940b5 239 // Set the MSB to 1
pairmand 3:8f2b7f4940b5 240 CRC = CRC | 0x80;
pairmand 3:8f2b7f4940b5 241 // Check bit 3
pairmand 3:8f2b7f4940b5 242 if (CRC & 0x04) {
pairmand 3:8f2b7f4940b5 243 CRC = CRC & 0xFB; // Bit 3 is set, so clear it
pairmand 3:8f2b7f4940b5 244 } else {
pairmand 3:8f2b7f4940b5 245 CRC = CRC | 0x04; // Bit 3 is clear, so set it
pairmand 3:8f2b7f4940b5 246 }
pairmand 3:8f2b7f4940b5 247 // Check bit 4
pairmand 3:8f2b7f4940b5 248 if (CRC & 0x08) {
pairmand 3:8f2b7f4940b5 249 CRC = CRC & 0xF7; // Bit 4 is set, so clear it
pairmand 3:8f2b7f4940b5 250 } else {
pairmand 3:8f2b7f4940b5 251 CRC = CRC | 0x08; // Bit 4 is clear, so set it
pairmand 3:8f2b7f4940b5 252 }
pairmand 3:8f2b7f4940b5 253 } else {
pairmand 3:8f2b7f4940b5 254 // DATA ^ LSB CRC = 0
pairmand 3:8f2b7f4940b5 255 CRC = CRC>>1;
pairmand 3:8f2b7f4940b5 256 // clear MSB
pairmand 3:8f2b7f4940b5 257 CRC = CRC & 0x7F;
pairmand 3:8f2b7f4940b5 258 // No need to check bits, with DATA ^ LSB CRC = 0, they will remain unchanged
pairmand 3:8f2b7f4940b5 259 }
pairmand 3:8f2b7f4940b5 260 byte = byte>>1;
pairmand 3:8f2b7f4940b5 261 }
pairmand 3:8f2b7f4940b5 262 return CRC;
pairmand 3:8f2b7f4940b5 263 }
pairmand 3:8f2b7f4940b5 264
Sissors 5:2cd4928e8147 265 int DS1820::convertTemperature(bool wait, devices device) {
pairmand 3:8f2b7f4940b5 266 // Convert temperature into scratchpad RAM for all devices at once
pairmand 3:8f2b7f4940b5 267 int delay_time = 750; // Default delay time
pairmand 3:8f2b7f4940b5 268 char resolution;
pairmand 3:8f2b7f4940b5 269 if (device==all_devices)
pairmand 3:8f2b7f4940b5 270 skip_ROM(); // Skip ROM command, will convert for ALL devices
pairmand 3:8f2b7f4940b5 271 else {
pairmand 3:8f2b7f4940b5 272 match_ROM();
Sissors 5:2cd4928e8147 273 if ((FAMILY_CODE == FAMILY_CODE_DS18B20 ) || (FAMILY_CODE == FAMILY_CODE_DS1822 )) {
pairmand 3:8f2b7f4940b5 274 resolution = RAM[4] & 0x60;
pairmand 3:8f2b7f4940b5 275 if (resolution == 0x00) // 9 bits
pairmand 3:8f2b7f4940b5 276 delay_time = 94;
pairmand 3:8f2b7f4940b5 277 if (resolution == 0x20) // 10 bits
pairmand 3:8f2b7f4940b5 278 delay_time = 188;
pairmand 3:8f2b7f4940b5 279 if (resolution == 0x40) // 11 bits. Note 12bits uses the 750ms default
pairmand 3:8f2b7f4940b5 280 delay_time = 375;
pairmand 3:8f2b7f4940b5 281 }
pairmand 3:8f2b7f4940b5 282 }
Sissors 5:2cd4928e8147 283
pairmand 3:8f2b7f4940b5 284 onewire_byte_out( 0x44); // perform temperature conversion
pairmand 3:8f2b7f4940b5 285 if (_parasite_power) {
Sissors 5:2cd4928e8147 286 if (_power_mosfet) {
Sissors 5:2cd4928e8147 287 _parasitepin = _power_polarity; // Parasite power strong pullup
Sissors 5:2cd4928e8147 288 wait_ms(delay_time);
Sissors 5:2cd4928e8147 289 _parasitepin = !_power_polarity;
Sissors 5:2cd4928e8147 290 delay_time = 0;
Sissors 5:2cd4928e8147 291 } else {
Sissors 5:2cd4928e8147 292 _datapin.output();
Sissors 5:2cd4928e8147 293 _datapin.write(1);
Sissors 5:2cd4928e8147 294 wait_ms(delay_time);
Sissors 5:2cd4928e8147 295 _datapin.input();
Sissors 5:2cd4928e8147 296 }
pairmand 3:8f2b7f4940b5 297 } else {
pairmand 3:8f2b7f4940b5 298 if (wait) {
pairmand 3:8f2b7f4940b5 299 wait_ms(delay_time);
pairmand 3:8f2b7f4940b5 300 delay_time = 0;
pairmand 3:8f2b7f4940b5 301 }
pairmand 3:8f2b7f4940b5 302 }
pairmand 3:8f2b7f4940b5 303 return delay_time;
pairmand 3:8f2b7f4940b5 304 }
pairmand 3:8f2b7f4940b5 305
pairmand 3:8f2b7f4940b5 306 void DS1820::read_RAM() {
pairmand 3:8f2b7f4940b5 307 // This will copy the DS1820's 9 bytes of RAM data
pairmand 3:8f2b7f4940b5 308 // into the objects RAM array. Functions that use
pairmand 3:8f2b7f4940b5 309 // RAM values will automaticly call this procedure.
pairmand 3:8f2b7f4940b5 310 int i;
pairmand 3:8f2b7f4940b5 311 match_ROM(); // Select this device
pairmand 3:8f2b7f4940b5 312 onewire_byte_out( 0xBE); //Read Scratchpad command
pairmand 3:8f2b7f4940b5 313 for(i=0;i<9;i++) {
pairmand 3:8f2b7f4940b5 314 RAM[i] = onewire_byte_in();
pairmand 3:8f2b7f4940b5 315 }
pairmand 3:8f2b7f4940b5 316 // if (!RAM_checksum_error())
pairmand 3:8f2b7f4940b5 317 // crcerr = 1;
pairmand 3:8f2b7f4940b5 318 }
pairmand 3:8f2b7f4940b5 319
Sissors 5:2cd4928e8147 320 bool DS1820::setResolution(unsigned int resolution) {
pairmand 3:8f2b7f4940b5 321 bool answer = false;
pairmand 3:8f2b7f4940b5 322 resolution = resolution - 9;
pairmand 3:8f2b7f4940b5 323 if (resolution < 4) {
pairmand 3:8f2b7f4940b5 324 resolution = resolution<<5; // align the bits
pairmand 3:8f2b7f4940b5 325 RAM[4] = (RAM[4] & 0x60) | resolution; // mask out old data, insert new
pairmand 3:8f2b7f4940b5 326 write_scratchpad ((RAM[2]<<8) + RAM[3]);
pairmand 3:8f2b7f4940b5 327 // store_scratchpad (DS1820::this_device); // Need to test if this is required
pairmand 3:8f2b7f4940b5 328 answer = true;
pairmand 3:8f2b7f4940b5 329 }
pairmand 3:8f2b7f4940b5 330 return answer;
pairmand 3:8f2b7f4940b5 331 }
pairmand 3:8f2b7f4940b5 332
pairmand 3:8f2b7f4940b5 333 void DS1820::write_scratchpad(int data) {
pairmand 3:8f2b7f4940b5 334 RAM[3] = data;
pairmand 3:8f2b7f4940b5 335 RAM[2] = data>>8;
pairmand 3:8f2b7f4940b5 336 match_ROM();
pairmand 3:8f2b7f4940b5 337 onewire_byte_out(0x4E); // Copy scratchpad into DS1820 ram memory
pairmand 3:8f2b7f4940b5 338 onewire_byte_out(RAM[2]); // T(H)
pairmand 3:8f2b7f4940b5 339 onewire_byte_out(RAM[3]); // T(L)
Sissors 5:2cd4928e8147 340 if ((FAMILY_CODE == FAMILY_CODE_DS18B20 ) || (FAMILY_CODE == FAMILY_CODE_DS1822 )) {
pairmand 3:8f2b7f4940b5 341 onewire_byte_out(RAM[4]); // Configuration register
pairmand 3:8f2b7f4940b5 342 }
pairmand 3:8f2b7f4940b5 343 }
pairmand 3:8f2b7f4940b5 344
pairmand 3:8f2b7f4940b5 345 float DS1820::temperature(char scale) {
pairmand 3:8f2b7f4940b5 346 // The data specs state that count_per_degree should be 0x10 (16), I found my devices
pairmand 3:8f2b7f4940b5 347 // to have a count_per_degree of 0x4B (75). With the standard resolution of 1/2 deg C
pairmand 3:8f2b7f4940b5 348 // this allowed an expanded resolution of 1/150th of a deg C. I wouldn't rely on this
pairmand 3:8f2b7f4940b5 349 // being super acurate, but it does allow for a smooth display in the 1/10ths of a
pairmand 3:8f2b7f4940b5 350 // deg C or F scales.
pairmand 3:8f2b7f4940b5 351 float answer, remaining_count, count_per_degree;
pairmand 3:8f2b7f4940b5 352 int reading;
pairmand 3:8f2b7f4940b5 353 read_RAM();
pairmand 3:8f2b7f4940b5 354 if (RAM_checksum_error())
pairmand 3:8f2b7f4940b5 355 // Indicate we got a CRC error
Sissors 7:58b61681818f 356 answer = invalid_conversion;
pairmand 3:8f2b7f4940b5 357 else {
pairmand 3:8f2b7f4940b5 358 reading = (RAM[1] << 8) + RAM[0];
pairmand 3:8f2b7f4940b5 359 if (reading & 0x8000) { // negative degrees C
pairmand 3:8f2b7f4940b5 360 reading = 0-((reading ^ 0xffff) + 1); // 2's comp then convert to signed int
pairmand 3:8f2b7f4940b5 361 }
pairmand 3:8f2b7f4940b5 362 answer = reading +0.0; // convert to floating point
Sissors 5:2cd4928e8147 363 if ((FAMILY_CODE == FAMILY_CODE_DS18B20 ) || (FAMILY_CODE == FAMILY_CODE_DS1822 )) {
pairmand 3:8f2b7f4940b5 364 answer = answer / 8.0;
pairmand 3:8f2b7f4940b5 365 }
pairmand 3:8f2b7f4940b5 366 else {
pairmand 3:8f2b7f4940b5 367 remaining_count = RAM[6];
pairmand 3:8f2b7f4940b5 368 count_per_degree = RAM[7];
pairmand 3:8f2b7f4940b5 369 answer = answer - 0.25 + (count_per_degree - remaining_count) / count_per_degree;
pairmand 3:8f2b7f4940b5 370 }
pairmand 3:8f2b7f4940b5 371 if (scale=='C' or scale=='c')
pairmand 3:8f2b7f4940b5 372 answer = answer / 2.0;
pairmand 3:8f2b7f4940b5 373 else
pairmand 3:8f2b7f4940b5 374 // Convert to deg F
pairmand 3:8f2b7f4940b5 375 answer = answer * 9.0 / 10.0 + 32.0;
pairmand 3:8f2b7f4940b5 376 }
pairmand 3:8f2b7f4940b5 377 return answer;
pairmand 3:8f2b7f4940b5 378 }
pairmand 3:8f2b7f4940b5 379
pairmand 3:8f2b7f4940b5 380 bool DS1820::read_power_supply(devices device) {
pairmand 3:8f2b7f4940b5 381 // This will return true if the device (or all devices) are Vcc powered
pairmand 3:8f2b7f4940b5 382 // This will return false if the device (or ANY device) is parasite powered
pairmand 3:8f2b7f4940b5 383 if (device==all_devices)
pairmand 3:8f2b7f4940b5 384 skip_ROM(); // Skip ROM command, will poll for any device using parasite power
pairmand 3:8f2b7f4940b5 385 else
pairmand 3:8f2b7f4940b5 386 match_ROM();
pairmand 3:8f2b7f4940b5 387 onewire_byte_out(0xB4); // Read power supply command
Sissors 5:2cd4928e8147 388 return onewire_bit_in(&this->_datapin);
pairmand 3:8f2b7f4940b5 389 }
pairmand 3:8f2b7f4940b5 390
pairmand 3:8f2b7f4940b5 391