Florian P / DS1820

I corrected found two bugs in your library: _the temperature reading is incorrect (systematic error in subdegree, the division by two was not done correctly + trunc, see below for correction) _one variable, _power_mosfet, was left unitialized under some conditions

Dependencies:   LinkedList

Fork of DS1820 by Erik -

DS1820.cpp@5:2cd4928e8147, 2014-02-24 (annotated)

Committer:
Sissors
Date:
Mon Feb 24 21:23:14 2014 +0000
Revision:
5:2cd4928e8147
Parent:
4:29264b0a2c9f
Child:
7:58b61681818f
Simplified code, works also on KL25Z now, added support for DS1822

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 5:2cd4928e8147 54 pin->input(); // 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 5:2cd4928e8147 58 pin->input();
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
pairmand 3:8f2b7f4940b5 356 answer = -1000.0;
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