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@4:29264b0a2c9f, 2013-08-07 (annotated)

Committer:
pairmand
Date:
Wed Aug 07 11:02:10 2013 +0000
Revision:
4:29264b0a2c9f
Parent:
3:8f2b7f4940b5
Child:
5:2cd4928e8147
Added check of CRC to end of search_ROM

Who changed what in which revision?

UserRevisionLine numberNew contents of line
pairmand 3:8f2b7f4940b5 1 #include "DS1820.h"
pairmand 3:8f2b7f4940b5 2 #include "mbed.h"
pairmand 3:8f2b7f4940b5 3
pairmand 3:8f2b7f4940b5 4 // Global variables shared between all DS1820 objects
pairmand 3:8f2b7f4940b5 5 bool DS1820_done_flag;
pairmand 3:8f2b7f4940b5 6 int DS1820_last_descrepancy;
pairmand 3:8f2b7f4940b5 7 char DS1820_search_ROM[8];
pairmand 3:8f2b7f4940b5 8
pairmand 3:8f2b7f4940b5 9
pairmand 3:8f2b7f4940b5 10 DS1820::DS1820 (PinName data_pin, PinName power_pin) : _datapin(data_pin), _parasitepin(power_pin) {
pairmand 3:8f2b7f4940b5 11 int byte_counter;
pairmand 3:8f2b7f4940b5 12 _parasite_power = true;
pairmand 3:8f2b7f4940b5 13 for(byte_counter=0;byte_counter<8;byte_counter++)
pairmand 3:8f2b7f4940b5 14 ROM[byte_counter] = 0xFF;
pairmand 3:8f2b7f4940b5 15 for(byte_counter=0;byte_counter<9;byte_counter++)
pairmand 3:8f2b7f4940b5 16 RAM[byte_counter] = 0x00;
pairmand 3:8f2b7f4940b5 17 }
pairmand 3:8f2b7f4940b5 18 DS1820::DS1820 (PinName data_pin) : _datapin(data_pin), _parasitepin(NC) {
pairmand 3:8f2b7f4940b5 19 int byte_counter;
pairmand 3:8f2b7f4940b5 20 _parasite_power = false;
pairmand 3:8f2b7f4940b5 21 for(byte_counter=0;byte_counter<8;byte_counter++)
pairmand 3:8f2b7f4940b5 22 ROM[byte_counter] = 0xFF;
pairmand 3:8f2b7f4940b5 23 for(byte_counter=0;byte_counter<9;byte_counter++)
pairmand 3:8f2b7f4940b5 24 RAM[byte_counter] = 0x00;
pairmand 3:8f2b7f4940b5 25 }
pairmand 3:8f2b7f4940b5 26
pairmand 3:8f2b7f4940b5 27 bool DS1820::onewire_reset() {
pairmand 3:8f2b7f4940b5 28 // This will return false if no devices are present on the data bus
pairmand 3:8f2b7f4940b5 29 bool presence=false;
pairmand 3:8f2b7f4940b5 30 _datapin.output();
pairmand 3:8f2b7f4940b5 31 _datapin = 0; // bring low for 500 us
pairmand 3:8f2b7f4940b5 32 wait_us(500);
pairmand 3:8f2b7f4940b5 33 _datapin.input(); // let the data line float high
pairmand 3:8f2b7f4940b5 34 wait_us(90); // wait 90us
pairmand 3:8f2b7f4940b5 35 if (_datapin.read()==0) // see if any devices are pulling the data line low
pairmand 3:8f2b7f4940b5 36 presence=true;
pairmand 3:8f2b7f4940b5 37 wait_us(410);
pairmand 3:8f2b7f4940b5 38 return presence;
pairmand 3:8f2b7f4940b5 39 }
pairmand 3:8f2b7f4940b5 40
pairmand 3:8f2b7f4940b5 41 void DS1820::onewire_bit_out (bool bit_data) {
pairmand 3:8f2b7f4940b5 42 _datapin.output();
pairmand 3:8f2b7f4940b5 43 _datapin = 0;
pairmand 3:8f2b7f4940b5 44 wait_us(3); // DXP modified from 5
pairmand 3:8f2b7f4940b5 45 if (bit_data) {
pairmand 3:8f2b7f4940b5 46 _datapin.input(); // bring data line high
pairmand 3:8f2b7f4940b5 47 wait_us(55);
pairmand 3:8f2b7f4940b5 48 } else {
pairmand 3:8f2b7f4940b5 49 wait_us(55); // keep data line low
pairmand 3:8f2b7f4940b5 50 _datapin.input();
pairmand 3:8f2b7f4940b5 51 wait_us(10); // DXP added to allow bus to float high before next bit_out
pairmand 3:8f2b7f4940b5 52 }
pairmand 3:8f2b7f4940b5 53 }
pairmand 3:8f2b7f4940b5 54
pairmand 3:8f2b7f4940b5 55 void DS1820::onewire_byte_out(char data) { // output data character (least sig bit first).
pairmand 3:8f2b7f4940b5 56 int n;
pairmand 3:8f2b7f4940b5 57 for (n=0; n<8; n++) {
pairmand 3:8f2b7f4940b5 58 onewire_bit_out(data & 0x01);
pairmand 3:8f2b7f4940b5 59 data = data >> 1; // now the next bit is in the least sig bit position.
pairmand 3:8f2b7f4940b5 60 }
pairmand 3:8f2b7f4940b5 61 }
pairmand 3:8f2b7f4940b5 62
pairmand 3:8f2b7f4940b5 63 bool DS1820::onewire_bit_in() {
pairmand 3:8f2b7f4940b5 64 bool answer;
pairmand 3:8f2b7f4940b5 65 _datapin.output();
pairmand 3:8f2b7f4940b5 66 _datapin = 0;
pairmand 3:8f2b7f4940b5 67 wait_us(3); // DXP modofied from 5
pairmand 3:8f2b7f4940b5 68 _datapin.input();
pairmand 3:8f2b7f4940b5 69 wait_us(10); // DXP modified from 5
pairmand 3:8f2b7f4940b5 70 answer = _datapin.read();
pairmand 3:8f2b7f4940b5 71 wait_us(45); // DXP modified from 50
pairmand 3:8f2b7f4940b5 72 return answer;
pairmand 3:8f2b7f4940b5 73 }
pairmand 3:8f2b7f4940b5 74
pairmand 3:8f2b7f4940b5 75 char DS1820::onewire_byte_in() { // read byte, least sig byte first
pairmand 3:8f2b7f4940b5 76 char answer = 0x00;
pairmand 3:8f2b7f4940b5 77 int i;
pairmand 3:8f2b7f4940b5 78 for (i=0; i<8; i++) {
pairmand 3:8f2b7f4940b5 79 answer = answer >> 1; // shift over to make room for the next bit
pairmand 3:8f2b7f4940b5 80 if (onewire_bit_in())
pairmand 3:8f2b7f4940b5 81 answer = answer | 0x80; // if the data port is high, make this bit a 1
pairmand 3:8f2b7f4940b5 82 }
pairmand 3:8f2b7f4940b5 83 return answer;
pairmand 3:8f2b7f4940b5 84 }
pairmand 3:8f2b7f4940b5 85
pairmand 3:8f2b7f4940b5 86 bool DS1820::search_ROM() {
pairmand 3:8f2b7f4940b5 87 return search_ROM_routine(0xF0); // Search ROM command
pairmand 3:8f2b7f4940b5 88 }
pairmand 3:8f2b7f4940b5 89
pairmand 3:8f2b7f4940b5 90 bool DS1820::search_alarm() {
pairmand 3:8f2b7f4940b5 91 return search_ROM_routine(0xEC); // Search Alarm command
pairmand 3:8f2b7f4940b5 92 }
pairmand 3:8f2b7f4940b5 93
pairmand 3:8f2b7f4940b5 94 bool DS1820::search_ROM_routine(char command) {
pairmand 3:8f2b7f4940b5 95 extern bool DS1820_done_flag;
pairmand 3:8f2b7f4940b5 96 extern int DS1820_last_descrepancy;
pairmand 3:8f2b7f4940b5 97 extern char DS1820_search_ROM[8];
pairmand 3:8f2b7f4940b5 98 int descrepancy_marker, ROM_bit_index;
pairmand 3:8f2b7f4940b5 99 bool return_value, Bit_A, Bit_B;
pairmand 3:8f2b7f4940b5 100 char byte_counter, bit_mask;
pairmand 3:8f2b7f4940b5 101
pairmand 3:8f2b7f4940b5 102 return_value=false;
pairmand 3:8f2b7f4940b5 103 if (!DS1820_done_flag) {
pairmand 3:8f2b7f4940b5 104 if (!onewire_reset()) {
pairmand 3:8f2b7f4940b5 105 DS1820_last_descrepancy = 0; // no devices present
pairmand 3:8f2b7f4940b5 106 } else {
pairmand 3:8f2b7f4940b5 107 ROM_bit_index=1;
pairmand 3:8f2b7f4940b5 108 descrepancy_marker=0;
pairmand 3:8f2b7f4940b5 109 onewire_byte_out(command); // Search ROM command or Search Alarm command
pairmand 3:8f2b7f4940b5 110 byte_counter = 0;
pairmand 3:8f2b7f4940b5 111 bit_mask = 0x01;
pairmand 3:8f2b7f4940b5 112 while (ROM_bit_index<=64) {
pairmand 3:8f2b7f4940b5 113 Bit_A = onewire_bit_in();
pairmand 3:8f2b7f4940b5 114 Bit_B = onewire_bit_in();
pairmand 3:8f2b7f4940b5 115 if (Bit_A & Bit_B) {
pairmand 3:8f2b7f4940b5 116 descrepancy_marker = 0; // data read error, this should never happen
pairmand 3:8f2b7f4940b5 117 ROM_bit_index = 0xFF;
pairmand 3:8f2b7f4940b5 118 } else {
pairmand 3:8f2b7f4940b5 119 if (Bit_A | Bit_B) {
pairmand 3:8f2b7f4940b5 120 // Set ROM bit to Bit_A
pairmand 3:8f2b7f4940b5 121 if (Bit_A) {
pairmand 3:8f2b7f4940b5 122 DS1820_search_ROM[byte_counter] = DS1820_search_ROM[byte_counter] | bit_mask; // Set ROM bit to one
pairmand 3:8f2b7f4940b5 123 } else {
pairmand 3:8f2b7f4940b5 124 DS1820_search_ROM[byte_counter] = DS1820_search_ROM[byte_counter] & ~bit_mask; // Set ROM bit to zero
pairmand 3:8f2b7f4940b5 125 }
pairmand 3:8f2b7f4940b5 126 } else {
pairmand 3:8f2b7f4940b5 127 // both bits A and B are low, so there are two or more devices present
pairmand 3:8f2b7f4940b5 128 if ( ROM_bit_index == DS1820_last_descrepancy ) {
pairmand 3:8f2b7f4940b5 129 DS1820_search_ROM[byte_counter] = DS1820_search_ROM[byte_counter] | bit_mask; // Set ROM bit to one
pairmand 3:8f2b7f4940b5 130 } else {
pairmand 3:8f2b7f4940b5 131 if ( ROM_bit_index > DS1820_last_descrepancy ) {
pairmand 3:8f2b7f4940b5 132 DS1820_search_ROM[byte_counter] = DS1820_search_ROM[byte_counter] & ~bit_mask; // Set ROM bit to zero
pairmand 3:8f2b7f4940b5 133 descrepancy_marker = ROM_bit_index;
pairmand 3:8f2b7f4940b5 134 } else {
pairmand 3:8f2b7f4940b5 135 if (( DS1820_search_ROM[byte_counter] & bit_mask) == 0x00 )
pairmand 3:8f2b7f4940b5 136 descrepancy_marker = ROM_bit_index;
pairmand 3:8f2b7f4940b5 137 }
pairmand 3:8f2b7f4940b5 138 }
pairmand 3:8f2b7f4940b5 139 }
pairmand 3:8f2b7f4940b5 140 onewire_bit_out (DS1820_search_ROM[byte_counter] & bit_mask);
pairmand 3:8f2b7f4940b5 141 ROM_bit_index++;
pairmand 3:8f2b7f4940b5 142 if (bit_mask & 0x80) {
pairmand 3:8f2b7f4940b5 143 byte_counter++;
pairmand 3:8f2b7f4940b5 144 bit_mask = 0x01;
pairmand 3:8f2b7f4940b5 145 } else {
pairmand 3:8f2b7f4940b5 146 bit_mask = bit_mask << 1;
pairmand 3:8f2b7f4940b5 147 }
pairmand 3:8f2b7f4940b5 148 }
pairmand 3:8f2b7f4940b5 149 }
pairmand 3:8f2b7f4940b5 150 DS1820_last_descrepancy = descrepancy_marker;
pairmand 3:8f2b7f4940b5 151 if (ROM_bit_index != 0xFF) {
pairmand 3:8f2b7f4940b5 152 for(byte_counter=0;byte_counter<8;byte_counter++)
pairmand 3:8f2b7f4940b5 153 ROM[byte_counter] = DS1820_search_ROM[byte_counter];
pairmand 4:29264b0a2c9f 154 if (ROM_checksum_error()) // Check the CRC
pairmand 4:29264b0a2c9f 155 DS1820_last_descrepancy = 0; // Abort any more search
pairmand 4:29264b0a2c9f 156 else
pairmand 4:29264b0a2c9f 157 return_value = true;
pairmand 3:8f2b7f4940b5 158 }
pairmand 3:8f2b7f4940b5 159 }
pairmand 3:8f2b7f4940b5 160 if (DS1820_last_descrepancy == 0)
pairmand 3:8f2b7f4940b5 161 DS1820_done_flag = true;
pairmand 3:8f2b7f4940b5 162 }
pairmand 3:8f2b7f4940b5 163 return return_value;
pairmand 3:8f2b7f4940b5 164 }
pairmand 3:8f2b7f4940b5 165
pairmand 3:8f2b7f4940b5 166 void DS1820::search_ROM_setup() {
pairmand 3:8f2b7f4940b5 167 extern bool DS1820_done_flag;
pairmand 3:8f2b7f4940b5 168 extern int DS1820_last_descrepancy;
pairmand 3:8f2b7f4940b5 169 extern char DS1820_search_ROM[8];
pairmand 3:8f2b7f4940b5 170 DS1820_done_flag = false;
pairmand 3:8f2b7f4940b5 171 DS1820_last_descrepancy = 0;
pairmand 3:8f2b7f4940b5 172 int i;
pairmand 3:8f2b7f4940b5 173 for (i=0; i<8; i++)
pairmand 3:8f2b7f4940b5 174 DS1820_search_ROM[i]=0x00;
pairmand 3:8f2b7f4940b5 175 }
pairmand 3:8f2b7f4940b5 176
pairmand 3:8f2b7f4940b5 177 void DS1820::read_ROM() {
pairmand 3:8f2b7f4940b5 178 // NOTE: This command can only be used when there is one DS1820 on the bus. If this command
pairmand 3:8f2b7f4940b5 179 // is used when there is more than one slave present on the bus, a data collision will occur
pairmand 3:8f2b7f4940b5 180 // when all the DS1820s attempt to respond at the same time.
pairmand 3:8f2b7f4940b5 181 int i;
pairmand 3:8f2b7f4940b5 182 onewire_reset();
pairmand 3:8f2b7f4940b5 183 onewire_byte_out(0x33); // Read ROM id
pairmand 3:8f2b7f4940b5 184 for (i=0; i<8; i++)
pairmand 3:8f2b7f4940b5 185 ROM[i]=onewire_byte_in();
pairmand 3:8f2b7f4940b5 186 }
pairmand 3:8f2b7f4940b5 187
pairmand 3:8f2b7f4940b5 188 void DS1820::match_ROM() {
pairmand 3:8f2b7f4940b5 189 // Used to select a specific device
pairmand 3:8f2b7f4940b5 190 int i;
pairmand 3:8f2b7f4940b5 191 onewire_reset();
pairmand 3:8f2b7f4940b5 192 onewire_byte_out( 0x55); //Match ROM command
pairmand 3:8f2b7f4940b5 193 for (i=0;i<8;i++)
pairmand 3:8f2b7f4940b5 194 onewire_byte_out(ROM[i]);
pairmand 3:8f2b7f4940b5 195 }
pairmand 3:8f2b7f4940b5 196
pairmand 3:8f2b7f4940b5 197 void DS1820::skip_ROM() {
pairmand 3:8f2b7f4940b5 198 onewire_reset();
pairmand 3:8f2b7f4940b5 199 onewire_byte_out(0xCC); // Skip ROM command
pairmand 3:8f2b7f4940b5 200 }
pairmand 3:8f2b7f4940b5 201
pairmand 3:8f2b7f4940b5 202 bool DS1820::ROM_checksum_error() {
pairmand 3:8f2b7f4940b5 203 char CRC=0x00;
pairmand 3:8f2b7f4940b5 204 int i;
pairmand 3:8f2b7f4940b5 205 for(i=0;i<7;i++) // Only going to shift the lower 7 bytes
pairmand 3:8f2b7f4940b5 206 CRC = CRC_byte(CRC, ROM[i]);
pairmand 3:8f2b7f4940b5 207 // After 7 bytes CRC should equal the 8th byte (ROM CRC)
pairmand 3:8f2b7f4940b5 208 return (CRC!=ROM[7]); // will return true if there is a CRC checksum mis-match
pairmand 3:8f2b7f4940b5 209 }
pairmand 3:8f2b7f4940b5 210
pairmand 3:8f2b7f4940b5 211 bool DS1820::RAM_checksum_error() {
pairmand 3:8f2b7f4940b5 212 char CRC=0x00;
pairmand 3:8f2b7f4940b5 213 int i;
pairmand 3:8f2b7f4940b5 214 for(i=0;i<8;i++) // Only going to shift the lower 8 bytes
pairmand 3:8f2b7f4940b5 215 CRC = CRC_byte(CRC, RAM[i]);
pairmand 3:8f2b7f4940b5 216 // After 8 bytes CRC should equal the 9th byte (RAM CRC)
pairmand 3:8f2b7f4940b5 217 return (CRC!=RAM[8]); // will return true if there is a CRC checksum mis-match
pairmand 3:8f2b7f4940b5 218 }
pairmand 3:8f2b7f4940b5 219
pairmand 3:8f2b7f4940b5 220 char DS1820::CRC_byte (char CRC, char byte ) {
pairmand 3:8f2b7f4940b5 221 int j;
pairmand 3:8f2b7f4940b5 222 for(j=0;j<8;j++) {
pairmand 3:8f2b7f4940b5 223 if ((byte & 0x01 ) ^ (CRC & 0x01)) {
pairmand 3:8f2b7f4940b5 224 // DATA ^ LSB CRC = 1
pairmand 3:8f2b7f4940b5 225 CRC = CRC>>1;
pairmand 3:8f2b7f4940b5 226 // Set the MSB to 1
pairmand 3:8f2b7f4940b5 227 CRC = CRC | 0x80;
pairmand 3:8f2b7f4940b5 228 // Check bit 3
pairmand 3:8f2b7f4940b5 229 if (CRC & 0x04) {
pairmand 3:8f2b7f4940b5 230 CRC = CRC & 0xFB; // Bit 3 is set, so clear it
pairmand 3:8f2b7f4940b5 231 } else {
pairmand 3:8f2b7f4940b5 232 CRC = CRC | 0x04; // Bit 3 is clear, so set it
pairmand 3:8f2b7f4940b5 233 }
pairmand 3:8f2b7f4940b5 234 // Check bit 4
pairmand 3:8f2b7f4940b5 235 if (CRC & 0x08) {
pairmand 3:8f2b7f4940b5 236 CRC = CRC & 0xF7; // Bit 4 is set, so clear it
pairmand 3:8f2b7f4940b5 237 } else {
pairmand 3:8f2b7f4940b5 238 CRC = CRC | 0x08; // Bit 4 is clear, so set it
pairmand 3:8f2b7f4940b5 239 }
pairmand 3:8f2b7f4940b5 240 } else {
pairmand 3:8f2b7f4940b5 241 // DATA ^ LSB CRC = 0
pairmand 3:8f2b7f4940b5 242 CRC = CRC>>1;
pairmand 3:8f2b7f4940b5 243 // clear MSB
pairmand 3:8f2b7f4940b5 244 CRC = CRC & 0x7F;
pairmand 3:8f2b7f4940b5 245 // No need to check bits, with DATA ^ LSB CRC = 0, they will remain unchanged
pairmand 3:8f2b7f4940b5 246 }
pairmand 3:8f2b7f4940b5 247 byte = byte>>1;
pairmand 3:8f2b7f4940b5 248 }
pairmand 3:8f2b7f4940b5 249 return CRC;
pairmand 3:8f2b7f4940b5 250 }
pairmand 3:8f2b7f4940b5 251
pairmand 3:8f2b7f4940b5 252 int DS1820::convert_temperature(bool wait, devices device) {
pairmand 3:8f2b7f4940b5 253 // Convert temperature into scratchpad RAM for all devices at once
pairmand 3:8f2b7f4940b5 254 int delay_time = 750; // Default delay time
pairmand 3:8f2b7f4940b5 255 char resolution;
pairmand 3:8f2b7f4940b5 256 if (device==all_devices)
pairmand 3:8f2b7f4940b5 257 skip_ROM(); // Skip ROM command, will convert for ALL devices
pairmand 3:8f2b7f4940b5 258 else {
pairmand 3:8f2b7f4940b5 259 match_ROM();
pairmand 3:8f2b7f4940b5 260 if (FAMILY_CODE == FAMILY_CODE_DS18B20 ) {
pairmand 3:8f2b7f4940b5 261 resolution = RAM[4] & 0x60;
pairmand 3:8f2b7f4940b5 262 if (resolution == 0x00) // 9 bits
pairmand 3:8f2b7f4940b5 263 delay_time = 94;
pairmand 3:8f2b7f4940b5 264 if (resolution == 0x20) // 10 bits
pairmand 3:8f2b7f4940b5 265 delay_time = 188;
pairmand 3:8f2b7f4940b5 266 if (resolution == 0x40) // 11 bits. Note 12bits uses the 750ms default
pairmand 3:8f2b7f4940b5 267 delay_time = 375;
pairmand 3:8f2b7f4940b5 268 }
pairmand 3:8f2b7f4940b5 269 }
pairmand 3:8f2b7f4940b5 270 onewire_byte_out( 0x44); // perform temperature conversion
pairmand 3:8f2b7f4940b5 271 if (_parasite_power) {
pairmand 3:8f2b7f4940b5 272 _parasitepin = 1; // Parasite power strong pullup
pairmand 3:8f2b7f4940b5 273 wait_ms(delay_time);
pairmand 3:8f2b7f4940b5 274 _parasitepin = 0;
pairmand 3:8f2b7f4940b5 275 delay_time = 0;
pairmand 3:8f2b7f4940b5 276 } else {
pairmand 3:8f2b7f4940b5 277 if (wait) {
pairmand 3:8f2b7f4940b5 278 wait_ms(delay_time);
pairmand 3:8f2b7f4940b5 279 delay_time = 0;
pairmand 3:8f2b7f4940b5 280 }
pairmand 3:8f2b7f4940b5 281 }
pairmand 3:8f2b7f4940b5 282 return delay_time;
pairmand 3:8f2b7f4940b5 283 }
pairmand 3:8f2b7f4940b5 284
pairmand 3:8f2b7f4940b5 285 void DS1820::read_RAM() {
pairmand 3:8f2b7f4940b5 286 // This will copy the DS1820's 9 bytes of RAM data
pairmand 3:8f2b7f4940b5 287 // into the objects RAM array. Functions that use
pairmand 3:8f2b7f4940b5 288 // RAM values will automaticly call this procedure.
pairmand 3:8f2b7f4940b5 289 int i;
pairmand 3:8f2b7f4940b5 290 match_ROM(); // Select this device
pairmand 3:8f2b7f4940b5 291 onewire_byte_out( 0xBE); //Read Scratchpad command
pairmand 3:8f2b7f4940b5 292 for(i=0;i<9;i++) {
pairmand 3:8f2b7f4940b5 293 RAM[i] = onewire_byte_in();
pairmand 3:8f2b7f4940b5 294 }
pairmand 3:8f2b7f4940b5 295 // if (!RAM_checksum_error())
pairmand 3:8f2b7f4940b5 296 // crcerr = 1;
pairmand 3:8f2b7f4940b5 297 }
pairmand 3:8f2b7f4940b5 298
pairmand 3:8f2b7f4940b5 299 bool DS1820::set_configuration_bits(unsigned int resolution) {
pairmand 3:8f2b7f4940b5 300 bool answer = false;
pairmand 3:8f2b7f4940b5 301 resolution = resolution - 9;
pairmand 3:8f2b7f4940b5 302 if (resolution < 4) {
pairmand 3:8f2b7f4940b5 303 resolution = resolution<<5; // align the bits
pairmand 3:8f2b7f4940b5 304 RAM[4] = (RAM[4] & 0x60) | resolution; // mask out old data, insert new
pairmand 3:8f2b7f4940b5 305 write_scratchpad ((RAM[2]<<8) + RAM[3]);
pairmand 3:8f2b7f4940b5 306 // store_scratchpad (DS1820::this_device); // Need to test if this is required
pairmand 3:8f2b7f4940b5 307 answer = true;
pairmand 3:8f2b7f4940b5 308 }
pairmand 3:8f2b7f4940b5 309 return answer;
pairmand 3:8f2b7f4940b5 310 }
pairmand 3:8f2b7f4940b5 311
pairmand 3:8f2b7f4940b5 312 int DS1820::read_scratchpad() {
pairmand 3:8f2b7f4940b5 313 int answer;
pairmand 3:8f2b7f4940b5 314 read_RAM();
pairmand 3:8f2b7f4940b5 315 answer = (RAM[2]<<8) + RAM[3];
pairmand 3:8f2b7f4940b5 316 return answer;
pairmand 3:8f2b7f4940b5 317 }
pairmand 3:8f2b7f4940b5 318
pairmand 3:8f2b7f4940b5 319 void DS1820::write_scratchpad(int data) {
pairmand 3:8f2b7f4940b5 320 RAM[3] = data;
pairmand 3:8f2b7f4940b5 321 RAM[2] = data>>8;
pairmand 3:8f2b7f4940b5 322 match_ROM();
pairmand 3:8f2b7f4940b5 323 onewire_byte_out(0x4E); // Copy scratchpad into DS1820 ram memory
pairmand 3:8f2b7f4940b5 324 onewire_byte_out(RAM[2]); // T(H)
pairmand 3:8f2b7f4940b5 325 onewire_byte_out(RAM[3]); // T(L)
pairmand 3:8f2b7f4940b5 326 if ( FAMILY_CODE == FAMILY_CODE_DS18B20 ) {
pairmand 3:8f2b7f4940b5 327 onewire_byte_out(RAM[4]); // Configuration register
pairmand 3:8f2b7f4940b5 328 }
pairmand 3:8f2b7f4940b5 329 }
pairmand 3:8f2b7f4940b5 330
pairmand 3:8f2b7f4940b5 331 void DS1820::store_scratchpad(devices device) {
pairmand 3:8f2b7f4940b5 332 if (device==all_devices)
pairmand 3:8f2b7f4940b5 333 skip_ROM(); // Skip ROM command, will store for ALL devices
pairmand 3:8f2b7f4940b5 334 else
pairmand 3:8f2b7f4940b5 335 match_ROM();
pairmand 3:8f2b7f4940b5 336 onewire_byte_out(0x48); // Write scratchpad into E2 command
pairmand 3:8f2b7f4940b5 337 if (_parasite_power)
pairmand 3:8f2b7f4940b5 338 _parasitepin=1;
pairmand 3:8f2b7f4940b5 339 wait_ms(10); // Parasite power strong pullup for 10ms
pairmand 3:8f2b7f4940b5 340 if (_parasite_power)
pairmand 3:8f2b7f4940b5 341 _parasitepin=0;
pairmand 3:8f2b7f4940b5 342 }
pairmand 3:8f2b7f4940b5 343
pairmand 3:8f2b7f4940b5 344 int DS1820::recall_scratchpad(devices device) {
pairmand 3:8f2b7f4940b5 345 // This copies the E2 values into the DS1820's memory.
pairmand 3:8f2b7f4940b5 346 // If you specify all_devices this will return zero, otherwise
pairmand 3:8f2b7f4940b5 347 // it will return the value of the scratchpad memory.
pairmand 3:8f2b7f4940b5 348 int answer=0;
pairmand 3:8f2b7f4940b5 349 if (device==all_devices)
pairmand 3:8f2b7f4940b5 350 skip_ROM(); // Skip ROM command, will recall for ALL devices
pairmand 3:8f2b7f4940b5 351 else
pairmand 3:8f2b7f4940b5 352 match_ROM();
pairmand 3:8f2b7f4940b5 353 onewire_byte_out(0xB8); // Recall E2 data to scratchpad command
pairmand 3:8f2b7f4940b5 354 wait_ms(10); // not sure I like polling for completion
pairmand 3:8f2b7f4940b5 355 // it could cause an infinite loop
pairmand 3:8f2b7f4940b5 356 if (device==DS1820::this_device) {
pairmand 3:8f2b7f4940b5 357 read_RAM();
pairmand 3:8f2b7f4940b5 358 answer = read_scratchpad();
pairmand 3:8f2b7f4940b5 359 }
pairmand 3:8f2b7f4940b5 360 return answer;
pairmand 3:8f2b7f4940b5 361 }
pairmand 3:8f2b7f4940b5 362
pairmand 3:8f2b7f4940b5 363 float DS1820::temperature(char scale) {
pairmand 3:8f2b7f4940b5 364 // The data specs state that count_per_degree should be 0x10 (16), I found my devices
pairmand 3:8f2b7f4940b5 365 // to have a count_per_degree of 0x4B (75). With the standard resolution of 1/2 deg C
pairmand 3:8f2b7f4940b5 366 // this allowed an expanded resolution of 1/150th of a deg C. I wouldn't rely on this
pairmand 3:8f2b7f4940b5 367 // being super acurate, but it does allow for a smooth display in the 1/10ths of a
pairmand 3:8f2b7f4940b5 368 // deg C or F scales.
pairmand 3:8f2b7f4940b5 369 float answer, remaining_count, count_per_degree;
pairmand 3:8f2b7f4940b5 370 int reading;
pairmand 3:8f2b7f4940b5 371 read_RAM();
pairmand 3:8f2b7f4940b5 372 if (RAM_checksum_error())
pairmand 3:8f2b7f4940b5 373 // Indicate we got a CRC error
pairmand 3:8f2b7f4940b5 374 answer = -1000.0;
pairmand 3:8f2b7f4940b5 375 else {
pairmand 3:8f2b7f4940b5 376 reading = (RAM[1] << 8) + RAM[0];
pairmand 3:8f2b7f4940b5 377 if (reading & 0x8000) { // negative degrees C
pairmand 3:8f2b7f4940b5 378 reading = 0-((reading ^ 0xffff) + 1); // 2's comp then convert to signed int
pairmand 3:8f2b7f4940b5 379 }
pairmand 3:8f2b7f4940b5 380 answer = reading +0.0; // convert to floating point
pairmand 3:8f2b7f4940b5 381 if ( FAMILY_CODE == FAMILY_CODE_DS18B20 ) {
pairmand 3:8f2b7f4940b5 382 answer = answer / 8.0;
pairmand 3:8f2b7f4940b5 383 }
pairmand 3:8f2b7f4940b5 384 else {
pairmand 3:8f2b7f4940b5 385 remaining_count = RAM[6];
pairmand 3:8f2b7f4940b5 386 count_per_degree = RAM[7];
pairmand 3:8f2b7f4940b5 387 answer = answer - 0.25 + (count_per_degree - remaining_count) / count_per_degree;
pairmand 3:8f2b7f4940b5 388 }
pairmand 3:8f2b7f4940b5 389 if (scale=='C' or scale=='c')
pairmand 3:8f2b7f4940b5 390 answer = answer / 2.0;
pairmand 3:8f2b7f4940b5 391 else
pairmand 3:8f2b7f4940b5 392 // Convert to deg F
pairmand 3:8f2b7f4940b5 393 answer = answer * 9.0 / 10.0 + 32.0;
pairmand 3:8f2b7f4940b5 394 }
pairmand 3:8f2b7f4940b5 395 return answer;
pairmand 3:8f2b7f4940b5 396 }
pairmand 3:8f2b7f4940b5 397
pairmand 3:8f2b7f4940b5 398 bool DS1820::read_power_supply(devices device) {
pairmand 3:8f2b7f4940b5 399 // This will return true if the device (or all devices) are Vcc powered
pairmand 3:8f2b7f4940b5 400 // This will return false if the device (or ANY device) is parasite powered
pairmand 3:8f2b7f4940b5 401 if (device==all_devices)
pairmand 3:8f2b7f4940b5 402 skip_ROM(); // Skip ROM command, will poll for any device using parasite power
pairmand 3:8f2b7f4940b5 403 else
pairmand 3:8f2b7f4940b5 404 match_ROM();
pairmand 3:8f2b7f4940b5 405 onewire_byte_out(0xB4); // Read power supply command
pairmand 3:8f2b7f4940b5 406 return onewire_bit_in();
pairmand 3:8f2b7f4940b5 407 }
pairmand 3:8f2b7f4940b5 408
pairmand 3:8f2b7f4940b5 409