Erik - / DS1820

Library for reading temperature from DS1820, DS18B20 and DS1822

Dependencies:   LinkedList

Dependents:   heatmap BLE_Temperature BLE_Temperature_Exercise F334andDS18B20 ... more

Fork of DS1820 by David Pairman

HelloWorld: http://mbed.org/users/Sissors/code/DS1820_HelloWorld/

Library should currently work on all mbed targets, let me know if there is an issue. First however make sure you have latest version of mbed library and this library.

DS1820.cpp@12:196e9e54b033, 2015-02-26 (annotated)

Committer:
Sissors
Date:
Thu Feb 26 22:20:24 2015 +0000
Revision:
12:196e9e54b033
Parent:
11:1a3c3002b50c
Child:
14:c591209285e9
Fixed issue with multplie probes

;

; The command byte got garbled after first sent, resulting in other runs no probes responding.

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;
florian 9:3821ca0b7f14 9
florian 9:3821ca0b7f14 10 _power_mosfet = power_pin != NC;
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 12:196e9e54b033 120 char command_shift = command;
Sissors 5:2cd4928e8147 121 for (int n=0; n<8; n++) { // Search ROM command or Search Alarm command
Sissors 12:196e9e54b033 122 onewire_bit_out(pin, command_shift & 0x01);
Sissors 12:196e9e54b033 123 command_shift = command_shift >> 1; // now the next bit is in the least sig bit position.
Sissors 5:2cd4928e8147 124 }
pairmand 3:8f2b7f4940b5 125 byte_counter = 0;
pairmand 3:8f2b7f4940b5 126 bit_mask = 0x01;
pairmand 3:8f2b7f4940b5 127 while (ROM_bit_index<=64) {
Sissors 5:2cd4928e8147 128 Bit_A = onewire_bit_in(pin);
Sissors 5:2cd4928e8147 129 Bit_B = onewire_bit_in(pin);
pairmand 3:8f2b7f4940b5 130 if (Bit_A & Bit_B) {
pairmand 3:8f2b7f4940b5 131 descrepancy_marker = 0; // data read error, this should never happen
pairmand 3:8f2b7f4940b5 132 ROM_bit_index = 0xFF;
pairmand 3:8f2b7f4940b5 133 } else {
pairmand 3:8f2b7f4940b5 134 if (Bit_A | Bit_B) {
pairmand 3:8f2b7f4940b5 135 // Set ROM bit to Bit_A
pairmand 3:8f2b7f4940b5 136 if (Bit_A) {
pairmand 3:8f2b7f4940b5 137 DS1820_search_ROM[byte_counter] = DS1820_search_ROM[byte_counter] | bit_mask; // Set ROM bit to one
pairmand 3:8f2b7f4940b5 138 } else {
pairmand 3:8f2b7f4940b5 139 DS1820_search_ROM[byte_counter] = DS1820_search_ROM[byte_counter] & ~bit_mask; // Set ROM bit to zero
pairmand 3:8f2b7f4940b5 140 }
pairmand 3:8f2b7f4940b5 141 } else {
pairmand 3:8f2b7f4940b5 142 // both bits A and B are low, so there are two or more devices present
pairmand 3:8f2b7f4940b5 143 if ( ROM_bit_index == DS1820_last_descrepancy ) {
pairmand 3:8f2b7f4940b5 144 DS1820_search_ROM[byte_counter] = DS1820_search_ROM[byte_counter] | bit_mask; // Set ROM bit to one
pairmand 3:8f2b7f4940b5 145 } else {
pairmand 3:8f2b7f4940b5 146 if ( ROM_bit_index > DS1820_last_descrepancy ) {
pairmand 3:8f2b7f4940b5 147 DS1820_search_ROM[byte_counter] = DS1820_search_ROM[byte_counter] & ~bit_mask; // Set ROM bit to zero
pairmand 3:8f2b7f4940b5 148 descrepancy_marker = ROM_bit_index;
pairmand 3:8f2b7f4940b5 149 } else {
pairmand 3:8f2b7f4940b5 150 if (( DS1820_search_ROM[byte_counter] & bit_mask) == 0x00 )
pairmand 3:8f2b7f4940b5 151 descrepancy_marker = ROM_bit_index;
pairmand 3:8f2b7f4940b5 152 }
pairmand 3:8f2b7f4940b5 153 }
pairmand 3:8f2b7f4940b5 154 }
Sissors 5:2cd4928e8147 155 onewire_bit_out (pin, DS1820_search_ROM[byte_counter] & bit_mask);
pairmand 3:8f2b7f4940b5 156 ROM_bit_index++;
pairmand 3:8f2b7f4940b5 157 if (bit_mask & 0x80) {
pairmand 3:8f2b7f4940b5 158 byte_counter++;
pairmand 3:8f2b7f4940b5 159 bit_mask = 0x01;
pairmand 3:8f2b7f4940b5 160 } else {
pairmand 3:8f2b7f4940b5 161 bit_mask = bit_mask << 1;
pairmand 3:8f2b7f4940b5 162 }
pairmand 3:8f2b7f4940b5 163 }
pairmand 3:8f2b7f4940b5 164 }
pairmand 3:8f2b7f4940b5 165 DS1820_last_descrepancy = descrepancy_marker;
pairmand 3:8f2b7f4940b5 166 if (ROM_bit_index != 0xFF) {
Sissors 5:2cd4928e8147 167 int i = 1;
Sissors 5:2cd4928e8147 168 node *list_container;
Sissors 5:2cd4928e8147 169 while(1) {
Sissors 5:2cd4928e8147 170 list_container = probes.pop(i);
Sissors 5:2cd4928e8147 171 if (list_container == NULL) { //End of list, or empty list
Sissors 5:2cd4928e8147 172 if (ROM_checksum_error(DS1820_search_ROM)) { // Check the CRC
Sissors 5:2cd4928e8147 173 return false;
Sissors 5:2cd4928e8147 174 }
Sissors 5:2cd4928e8147 175 for(byte_counter=0;byte_counter<8;byte_counter++)
Sissors 5:2cd4928e8147 176 ROM_address[byte_counter] = DS1820_search_ROM[byte_counter];
Sissors 5:2cd4928e8147 177 return true;
Sissors 5:2cd4928e8147 178 } else { //Otherwise, check if ROM is already known
Sissors 5:2cd4928e8147 179 bool equal = true;
Sissors 5:2cd4928e8147 180 DS1820 *pointer = (DS1820*) list_container->data;
Sissors 5:2cd4928e8147 181 char *ROM_compare = pointer->_ROM;
Sissors 5:2cd4928e8147 182
Sissors 5:2cd4928e8147 183 for(byte_counter=0;byte_counter<8;byte_counter++) {
Sissors 5:2cd4928e8147 184 if ( ROM_compare[byte_counter] != DS1820_search_ROM[byte_counter])
Sissors 5:2cd4928e8147 185 equal = false;
Sissors 5:2cd4928e8147 186 }
Sissors 5:2cd4928e8147 187 if (equal)
Sissors 5:2cd4928e8147 188 break;
Sissors 5:2cd4928e8147 189 else
Sissors 5:2cd4928e8147 190 i++;
Sissors 5:2cd4928e8147 191 }
Sissors 5:2cd4928e8147 192 }
pairmand 3:8f2b7f4940b5 193 }
pairmand 3:8f2b7f4940b5 194 }
pairmand 3:8f2b7f4940b5 195 if (DS1820_last_descrepancy == 0)
pairmand 3:8f2b7f4940b5 196 DS1820_done_flag = true;
pairmand 3:8f2b7f4940b5 197 }
pairmand 3:8f2b7f4940b5 198 return return_value;
pairmand 3:8f2b7f4940b5 199 }
pairmand 3:8f2b7f4940b5 200
pairmand 3:8f2b7f4940b5 201 void DS1820::match_ROM() {
pairmand 3:8f2b7f4940b5 202 // Used to select a specific device
pairmand 3:8f2b7f4940b5 203 int i;
Sissors 5:2cd4928e8147 204 onewire_reset(&this->_datapin);
pairmand 3:8f2b7f4940b5 205 onewire_byte_out( 0x55); //Match ROM command
Sissors 5:2cd4928e8147 206 for (i=0;i<8;i++) {
Sissors 5:2cd4928e8147 207 onewire_byte_out(_ROM[i]);
Sissors 5:2cd4928e8147 208 }
pairmand 3:8f2b7f4940b5 209 }
pairmand 3:8f2b7f4940b5 210
pairmand 3:8f2b7f4940b5 211 void DS1820::skip_ROM() {
Sissors 5:2cd4928e8147 212 onewire_reset(&this->_datapin);
pairmand 3:8f2b7f4940b5 213 onewire_byte_out(0xCC); // Skip ROM command
pairmand 3:8f2b7f4940b5 214 }
pairmand 3:8f2b7f4940b5 215
Sissors 5:2cd4928e8147 216 bool DS1820::ROM_checksum_error(char *_ROM_address) {
Sissors 11:1a3c3002b50c 217 char _CRC=0x00;
pairmand 3:8f2b7f4940b5 218 int i;
pairmand 3:8f2b7f4940b5 219 for(i=0;i<7;i++) // Only going to shift the lower 7 bytes
Sissors 11:1a3c3002b50c 220 _CRC = CRC_byte(_CRC, _ROM_address[i]);
pairmand 3:8f2b7f4940b5 221 // After 7 bytes CRC should equal the 8th byte (ROM CRC)
Sissors 11:1a3c3002b50c 222 return (_CRC!=_ROM_address[7]); // will return true if there is a CRC checksum mis-match
pairmand 3:8f2b7f4940b5 223 }
pairmand 3:8f2b7f4940b5 224
pairmand 3:8f2b7f4940b5 225 bool DS1820::RAM_checksum_error() {
Sissors 11:1a3c3002b50c 226 char _CRC=0x00;
pairmand 3:8f2b7f4940b5 227 int i;
pairmand 3:8f2b7f4940b5 228 for(i=0;i<8;i++) // Only going to shift the lower 8 bytes
Sissors 11:1a3c3002b50c 229 _CRC = CRC_byte(_CRC, RAM[i]);
pairmand 3:8f2b7f4940b5 230 // After 8 bytes CRC should equal the 9th byte (RAM CRC)
Sissors 11:1a3c3002b50c 231 return (_CRC!=RAM[8]); // will return true if there is a CRC checksum mis-match
pairmand 3:8f2b7f4940b5 232 }
pairmand 3:8f2b7f4940b5 233
Sissors 11:1a3c3002b50c 234 char DS1820::CRC_byte (char _CRC, char byte ) {
pairmand 3:8f2b7f4940b5 235 int j;
pairmand 3:8f2b7f4940b5 236 for(j=0;j<8;j++) {
Sissors 11:1a3c3002b50c 237 if ((byte & 0x01 ) ^ (_CRC & 0x01)) {
pairmand 3:8f2b7f4940b5 238 // DATA ^ LSB CRC = 1
Sissors 11:1a3c3002b50c 239 _CRC = _CRC>>1;
pairmand 3:8f2b7f4940b5 240 // Set the MSB to 1
Sissors 11:1a3c3002b50c 241 _CRC = _CRC | 0x80;
pairmand 3:8f2b7f4940b5 242 // Check bit 3
Sissors 11:1a3c3002b50c 243 if (_CRC & 0x04) {
Sissors 11:1a3c3002b50c 244 _CRC = _CRC & 0xFB; // Bit 3 is set, so clear it
pairmand 3:8f2b7f4940b5 245 } else {
Sissors 11:1a3c3002b50c 246 _CRC = _CRC | 0x04; // Bit 3 is clear, so set it
pairmand 3:8f2b7f4940b5 247 }
pairmand 3:8f2b7f4940b5 248 // Check bit 4
Sissors 11:1a3c3002b50c 249 if (_CRC & 0x08) {
Sissors 11:1a3c3002b50c 250 _CRC = _CRC & 0xF7; // Bit 4 is set, so clear it
pairmand 3:8f2b7f4940b5 251 } else {
Sissors 11:1a3c3002b50c 252 _CRC = _CRC | 0x08; // Bit 4 is clear, so set it
pairmand 3:8f2b7f4940b5 253 }
pairmand 3:8f2b7f4940b5 254 } else {
pairmand 3:8f2b7f4940b5 255 // DATA ^ LSB CRC = 0
Sissors 11:1a3c3002b50c 256 _CRC = _CRC>>1;
pairmand 3:8f2b7f4940b5 257 // clear MSB
Sissors 11:1a3c3002b50c 258 _CRC = _CRC & 0x7F;
pairmand 3:8f2b7f4940b5 259 // No need to check bits, with DATA ^ LSB CRC = 0, they will remain unchanged
pairmand 3:8f2b7f4940b5 260 }
pairmand 3:8f2b7f4940b5 261 byte = byte>>1;
pairmand 3:8f2b7f4940b5 262 }
Sissors 11:1a3c3002b50c 263 return _CRC;
pairmand 3:8f2b7f4940b5 264 }
pairmand 3:8f2b7f4940b5 265
Sissors 5:2cd4928e8147 266 int DS1820::convertTemperature(bool wait, devices device) {
pairmand 3:8f2b7f4940b5 267 // Convert temperature into scratchpad RAM for all devices at once
pairmand 3:8f2b7f4940b5 268 int delay_time = 750; // Default delay time
pairmand 3:8f2b7f4940b5 269 char resolution;
pairmand 3:8f2b7f4940b5 270 if (device==all_devices)
pairmand 3:8f2b7f4940b5 271 skip_ROM(); // Skip ROM command, will convert for ALL devices
pairmand 3:8f2b7f4940b5 272 else {
pairmand 3:8f2b7f4940b5 273 match_ROM();
Sissors 5:2cd4928e8147 274 if ((FAMILY_CODE == FAMILY_CODE_DS18B20 ) || (FAMILY_CODE == FAMILY_CODE_DS1822 )) {
pairmand 3:8f2b7f4940b5 275 resolution = RAM[4] & 0x60;
pairmand 3:8f2b7f4940b5 276 if (resolution == 0x00) // 9 bits
pairmand 3:8f2b7f4940b5 277 delay_time = 94;
pairmand 3:8f2b7f4940b5 278 if (resolution == 0x20) // 10 bits
pairmand 3:8f2b7f4940b5 279 delay_time = 188;
pairmand 3:8f2b7f4940b5 280 if (resolution == 0x40) // 11 bits. Note 12bits uses the 750ms default
pairmand 3:8f2b7f4940b5 281 delay_time = 375;
pairmand 3:8f2b7f4940b5 282 }
pairmand 3:8f2b7f4940b5 283 }
Sissors 5:2cd4928e8147 284
pairmand 3:8f2b7f4940b5 285 onewire_byte_out( 0x44); // perform temperature conversion
pairmand 3:8f2b7f4940b5 286 if (_parasite_power) {
Sissors 5:2cd4928e8147 287 if (_power_mosfet) {
Sissors 5:2cd4928e8147 288 _parasitepin = _power_polarity; // Parasite power strong pullup
Sissors 5:2cd4928e8147 289 wait_ms(delay_time);
Sissors 5:2cd4928e8147 290 _parasitepin = !_power_polarity;
Sissors 5:2cd4928e8147 291 delay_time = 0;
Sissors 5:2cd4928e8147 292 } else {
Sissors 5:2cd4928e8147 293 _datapin.output();
Sissors 5:2cd4928e8147 294 _datapin.write(1);
Sissors 5:2cd4928e8147 295 wait_ms(delay_time);
Sissors 5:2cd4928e8147 296 _datapin.input();
Sissors 5:2cd4928e8147 297 }
pairmand 3:8f2b7f4940b5 298 } else {
pairmand 3:8f2b7f4940b5 299 if (wait) {
pairmand 3:8f2b7f4940b5 300 wait_ms(delay_time);
pairmand 3:8f2b7f4940b5 301 delay_time = 0;
pairmand 3:8f2b7f4940b5 302 }
pairmand 3:8f2b7f4940b5 303 }
pairmand 3:8f2b7f4940b5 304 return delay_time;
pairmand 3:8f2b7f4940b5 305 }
pairmand 3:8f2b7f4940b5 306
pairmand 3:8f2b7f4940b5 307 void DS1820::read_RAM() {
pairmand 3:8f2b7f4940b5 308 // This will copy the DS1820's 9 bytes of RAM data
pairmand 3:8f2b7f4940b5 309 // into the objects RAM array. Functions that use
pairmand 3:8f2b7f4940b5 310 // RAM values will automaticly call this procedure.
pairmand 3:8f2b7f4940b5 311 int i;
pairmand 3:8f2b7f4940b5 312 match_ROM(); // Select this device
pairmand 3:8f2b7f4940b5 313 onewire_byte_out( 0xBE); //Read Scratchpad command
pairmand 3:8f2b7f4940b5 314 for(i=0;i<9;i++) {
pairmand 3:8f2b7f4940b5 315 RAM[i] = onewire_byte_in();
pairmand 3:8f2b7f4940b5 316 }
pairmand 3:8f2b7f4940b5 317 // if (!RAM_checksum_error())
pairmand 3:8f2b7f4940b5 318 // crcerr = 1;
pairmand 3:8f2b7f4940b5 319 }
pairmand 3:8f2b7f4940b5 320
Sissors 5:2cd4928e8147 321 bool DS1820::setResolution(unsigned int resolution) {
pairmand 3:8f2b7f4940b5 322 bool answer = false;
pairmand 3:8f2b7f4940b5 323 resolution = resolution - 9;
pairmand 3:8f2b7f4940b5 324 if (resolution < 4) {
pairmand 3:8f2b7f4940b5 325 resolution = resolution<<5; // align the bits
pairmand 3:8f2b7f4940b5 326 RAM[4] = (RAM[4] & 0x60) | resolution; // mask out old data, insert new
pairmand 3:8f2b7f4940b5 327 write_scratchpad ((RAM[2]<<8) + RAM[3]);
pairmand 3:8f2b7f4940b5 328 // store_scratchpad (DS1820::this_device); // Need to test if this is required
pairmand 3:8f2b7f4940b5 329 answer = true;
pairmand 3:8f2b7f4940b5 330 }
pairmand 3:8f2b7f4940b5 331 return answer;
pairmand 3:8f2b7f4940b5 332 }
pairmand 3:8f2b7f4940b5 333
pairmand 3:8f2b7f4940b5 334 void DS1820::write_scratchpad(int data) {
pairmand 3:8f2b7f4940b5 335 RAM[3] = data;
pairmand 3:8f2b7f4940b5 336 RAM[2] = data>>8;
pairmand 3:8f2b7f4940b5 337 match_ROM();
pairmand 3:8f2b7f4940b5 338 onewire_byte_out(0x4E); // Copy scratchpad into DS1820 ram memory
pairmand 3:8f2b7f4940b5 339 onewire_byte_out(RAM[2]); // T(H)
pairmand 3:8f2b7f4940b5 340 onewire_byte_out(RAM[3]); // T(L)
Sissors 5:2cd4928e8147 341 if ((FAMILY_CODE == FAMILY_CODE_DS18B20 ) || (FAMILY_CODE == FAMILY_CODE_DS1822 )) {
pairmand 3:8f2b7f4940b5 342 onewire_byte_out(RAM[4]); // Configuration register
pairmand 3:8f2b7f4940b5 343 }
pairmand 3:8f2b7f4940b5 344 }
pairmand 3:8f2b7f4940b5 345
pairmand 3:8f2b7f4940b5 346 float DS1820::temperature(char scale) {
pairmand 3:8f2b7f4940b5 347 // The data specs state that count_per_degree should be 0x10 (16), I found my devices
pairmand 3:8f2b7f4940b5 348 // to have a count_per_degree of 0x4B (75). With the standard resolution of 1/2 deg C
pairmand 3:8f2b7f4940b5 349 // this allowed an expanded resolution of 1/150th of a deg C. I wouldn't rely on this
pairmand 3:8f2b7f4940b5 350 // being super acurate, but it does allow for a smooth display in the 1/10ths of a
pairmand 3:8f2b7f4940b5 351 // deg C or F scales.
pairmand 3:8f2b7f4940b5 352 float answer, remaining_count, count_per_degree;
pairmand 3:8f2b7f4940b5 353 int reading;
pairmand 3:8f2b7f4940b5 354 read_RAM();
pairmand 3:8f2b7f4940b5 355 if (RAM_checksum_error())
pairmand 3:8f2b7f4940b5 356 // Indicate we got a CRC error
Sissors 7:58b61681818f 357 answer = invalid_conversion;
pairmand 3:8f2b7f4940b5 358 else {
pairmand 3:8f2b7f4940b5 359 reading = (RAM[1] << 8) + RAM[0];
pairmand 3:8f2b7f4940b5 360 if (reading & 0x8000) { // negative degrees C
pairmand 3:8f2b7f4940b5 361 reading = 0-((reading ^ 0xffff) + 1); // 2's comp then convert to signed int
pairmand 3:8f2b7f4940b5 362 }
pairmand 3:8f2b7f4940b5 363 answer = reading +0.0; // convert to floating point
Sissors 5:2cd4928e8147 364 if ((FAMILY_CODE == FAMILY_CODE_DS18B20 ) || (FAMILY_CODE == FAMILY_CODE_DS1822 )) {
Sissors 11:1a3c3002b50c 365 answer = answer / 16.0f;
pairmand 3:8f2b7f4940b5 366 }
pairmand 3:8f2b7f4940b5 367 else {
pairmand 3:8f2b7f4940b5 368 remaining_count = RAM[6];
pairmand 3:8f2b7f4940b5 369 count_per_degree = RAM[7];
Sissors 11:1a3c3002b50c 370 answer = floor(answer/2.0f) - 0.25f + (count_per_degree - remaining_count) / count_per_degree;
pairmand 3:8f2b7f4940b5 371 }
florian 10:d297ce9ce422 372 if (scale=='F' or scale=='f')
pairmand 3:8f2b7f4940b5 373 // Convert to deg F
Sissors 11:1a3c3002b50c 374 answer = answer * 9.0f / 5.0f + 32.0f;
pairmand 3:8f2b7f4940b5 375 }
pairmand 3:8f2b7f4940b5 376 return answer;
pairmand 3:8f2b7f4940b5 377 }
pairmand 3:8f2b7f4940b5 378
pairmand 3:8f2b7f4940b5 379 bool DS1820::read_power_supply(devices device) {
pairmand 3:8f2b7f4940b5 380 // This will return true if the device (or all devices) are Vcc powered
pairmand 3:8f2b7f4940b5 381 // This will return false if the device (or ANY device) is parasite powered
pairmand 3:8f2b7f4940b5 382 if (device==all_devices)
pairmand 3:8f2b7f4940b5 383 skip_ROM(); // Skip ROM command, will poll for any device using parasite power
pairmand 3:8f2b7f4940b5 384 else
pairmand 3:8f2b7f4940b5 385 match_ROM();
pairmand 3:8f2b7f4940b5 386 onewire_byte_out(0xB4); // Read power supply command
Sissors 5:2cd4928e8147 387 return onewire_bit_in(&this->_datapin);
pairmand 3:8f2b7f4940b5 388 }
pairmand 3:8f2b7f4940b5 389
pairmand 3:8f2b7f4940b5 390