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@3:8f2b7f4940b5, 2013-08-01 (annotated)

Committer:
pairmand
Date:
Thu Aug 01 10:18:17 2013 +0000
Revision:
3:8f2b7f4940b5
Parent:
2:ee820a991b95
Child:
4:29264b0a2c9f
Fixed to work with latest library version, allowed immediate return from convert_temperature(), and tidied up a few other things.

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 3:8f2b7f4940b5 154 return_value = true;
pairmand 3:8f2b7f4940b5 155 }
pairmand 3:8f2b7f4940b5 156 }
pairmand 3:8f2b7f4940b5 157 if (DS1820_last_descrepancy == 0)
pairmand 3:8f2b7f4940b5 158 DS1820_done_flag = true;
pairmand 3:8f2b7f4940b5 159 }
pairmand 3:8f2b7f4940b5 160 return return_value;
pairmand 3:8f2b7f4940b5 161 }
pairmand 3:8f2b7f4940b5 162
pairmand 3:8f2b7f4940b5 163 void DS1820::search_ROM_setup() {
pairmand 3:8f2b7f4940b5 164 extern bool DS1820_done_flag;
pairmand 3:8f2b7f4940b5 165 extern int DS1820_last_descrepancy;
pairmand 3:8f2b7f4940b5 166 extern char DS1820_search_ROM[8];
pairmand 3:8f2b7f4940b5 167 DS1820_done_flag = false;
pairmand 3:8f2b7f4940b5 168 DS1820_last_descrepancy = 0;
pairmand 3:8f2b7f4940b5 169 int i;
pairmand 3:8f2b7f4940b5 170 for (i=0; i<8; i++)
pairmand 3:8f2b7f4940b5 171 DS1820_search_ROM[i]=0x00;
pairmand 3:8f2b7f4940b5 172 }
pairmand 3:8f2b7f4940b5 173
pairmand 3:8f2b7f4940b5 174 void DS1820::read_ROM() {
pairmand 3:8f2b7f4940b5 175 // NOTE: This command can only be used when there is one DS1820 on the bus. If this command
pairmand 3:8f2b7f4940b5 176 // is used when there is more than one slave present on the bus, a data collision will occur
pairmand 3:8f2b7f4940b5 177 // when all the DS1820s attempt to respond at the same time.
pairmand 3:8f2b7f4940b5 178 int i;
pairmand 3:8f2b7f4940b5 179 onewire_reset();
pairmand 3:8f2b7f4940b5 180 onewire_byte_out(0x33); // Read ROM id
pairmand 3:8f2b7f4940b5 181 for (i=0; i<8; i++)
pairmand 3:8f2b7f4940b5 182 ROM[i]=onewire_byte_in();
pairmand 3:8f2b7f4940b5 183 }
pairmand 3:8f2b7f4940b5 184
pairmand 3:8f2b7f4940b5 185 void DS1820::match_ROM() {
pairmand 3:8f2b7f4940b5 186 // Used to select a specific device
pairmand 3:8f2b7f4940b5 187 int i;
pairmand 3:8f2b7f4940b5 188 onewire_reset();
pairmand 3:8f2b7f4940b5 189 onewire_byte_out( 0x55); //Match ROM command
pairmand 3:8f2b7f4940b5 190 for (i=0;i<8;i++)
pairmand 3:8f2b7f4940b5 191 onewire_byte_out(ROM[i]);
pairmand 3:8f2b7f4940b5 192 }
pairmand 3:8f2b7f4940b5 193
pairmand 3:8f2b7f4940b5 194 void DS1820::skip_ROM() {
pairmand 3:8f2b7f4940b5 195 onewire_reset();
pairmand 3:8f2b7f4940b5 196 onewire_byte_out(0xCC); // Skip ROM command
pairmand 3:8f2b7f4940b5 197 }
pairmand 3:8f2b7f4940b5 198
pairmand 3:8f2b7f4940b5 199 bool DS1820::ROM_checksum_error() {
pairmand 3:8f2b7f4940b5 200 char CRC=0x00;
pairmand 3:8f2b7f4940b5 201 int i;
pairmand 3:8f2b7f4940b5 202 for(i=0;i<7;i++) // Only going to shift the lower 7 bytes
pairmand 3:8f2b7f4940b5 203 CRC = CRC_byte(CRC, ROM[i]);
pairmand 3:8f2b7f4940b5 204 // After 7 bytes CRC should equal the 8th byte (ROM CRC)
pairmand 3:8f2b7f4940b5 205 return (CRC!=ROM[7]); // will return true if there is a CRC checksum mis-match
pairmand 3:8f2b7f4940b5 206 }
pairmand 3:8f2b7f4940b5 207
pairmand 3:8f2b7f4940b5 208 bool DS1820::RAM_checksum_error() {
pairmand 3:8f2b7f4940b5 209 char CRC=0x00;
pairmand 3:8f2b7f4940b5 210 int i;
pairmand 3:8f2b7f4940b5 211 for(i=0;i<8;i++) // Only going to shift the lower 8 bytes
pairmand 3:8f2b7f4940b5 212 CRC = CRC_byte(CRC, RAM[i]);
pairmand 3:8f2b7f4940b5 213 // After 8 bytes CRC should equal the 9th byte (RAM CRC)
pairmand 3:8f2b7f4940b5 214 return (CRC!=RAM[8]); // will return true if there is a CRC checksum mis-match
pairmand 3:8f2b7f4940b5 215 }
pairmand 3:8f2b7f4940b5 216
pairmand 3:8f2b7f4940b5 217 char DS1820::CRC_byte (char CRC, char byte ) {
pairmand 3:8f2b7f4940b5 218 int j;
pairmand 3:8f2b7f4940b5 219 for(j=0;j<8;j++) {
pairmand 3:8f2b7f4940b5 220 if ((byte & 0x01 ) ^ (CRC & 0x01)) {
pairmand 3:8f2b7f4940b5 221 // DATA ^ LSB CRC = 1
pairmand 3:8f2b7f4940b5 222 CRC = CRC>>1;
pairmand 3:8f2b7f4940b5 223 // Set the MSB to 1
pairmand 3:8f2b7f4940b5 224 CRC = CRC | 0x80;
pairmand 3:8f2b7f4940b5 225 // Check bit 3
pairmand 3:8f2b7f4940b5 226 if (CRC & 0x04) {
pairmand 3:8f2b7f4940b5 227 CRC = CRC & 0xFB; // Bit 3 is set, so clear it
pairmand 3:8f2b7f4940b5 228 } else {
pairmand 3:8f2b7f4940b5 229 CRC = CRC | 0x04; // Bit 3 is clear, so set it
pairmand 3:8f2b7f4940b5 230 }
pairmand 3:8f2b7f4940b5 231 // Check bit 4
pairmand 3:8f2b7f4940b5 232 if (CRC & 0x08) {
pairmand 3:8f2b7f4940b5 233 CRC = CRC & 0xF7; // Bit 4 is set, so clear it
pairmand 3:8f2b7f4940b5 234 } else {
pairmand 3:8f2b7f4940b5 235 CRC = CRC | 0x08; // Bit 4 is clear, so set it
pairmand 3:8f2b7f4940b5 236 }
pairmand 3:8f2b7f4940b5 237 } else {
pairmand 3:8f2b7f4940b5 238 // DATA ^ LSB CRC = 0
pairmand 3:8f2b7f4940b5 239 CRC = CRC>>1;
pairmand 3:8f2b7f4940b5 240 // clear MSB
pairmand 3:8f2b7f4940b5 241 CRC = CRC & 0x7F;
pairmand 3:8f2b7f4940b5 242 // No need to check bits, with DATA ^ LSB CRC = 0, they will remain unchanged
pairmand 3:8f2b7f4940b5 243 }
pairmand 3:8f2b7f4940b5 244 byte = byte>>1;
pairmand 3:8f2b7f4940b5 245 }
pairmand 3:8f2b7f4940b5 246 return CRC;
pairmand 3:8f2b7f4940b5 247 }
pairmand 3:8f2b7f4940b5 248
pairmand 3:8f2b7f4940b5 249 int DS1820::convert_temperature(bool wait, devices device) {
pairmand 3:8f2b7f4940b5 250 // Convert temperature into scratchpad RAM for all devices at once
pairmand 3:8f2b7f4940b5 251 int delay_time = 750; // Default delay time
pairmand 3:8f2b7f4940b5 252 char resolution;
pairmand 3:8f2b7f4940b5 253 if (device==all_devices)
pairmand 3:8f2b7f4940b5 254 skip_ROM(); // Skip ROM command, will convert for ALL devices
pairmand 3:8f2b7f4940b5 255 else {
pairmand 3:8f2b7f4940b5 256 match_ROM();
pairmand 3:8f2b7f4940b5 257 if (FAMILY_CODE == FAMILY_CODE_DS18B20 ) {
pairmand 3:8f2b7f4940b5 258 resolution = RAM[4] & 0x60;
pairmand 3:8f2b7f4940b5 259 if (resolution == 0x00) // 9 bits
pairmand 3:8f2b7f4940b5 260 delay_time = 94;
pairmand 3:8f2b7f4940b5 261 if (resolution == 0x20) // 10 bits
pairmand 3:8f2b7f4940b5 262 delay_time = 188;
pairmand 3:8f2b7f4940b5 263 if (resolution == 0x40) // 11 bits. Note 12bits uses the 750ms default
pairmand 3:8f2b7f4940b5 264 delay_time = 375;
pairmand 3:8f2b7f4940b5 265 }
pairmand 3:8f2b7f4940b5 266 }
pairmand 3:8f2b7f4940b5 267 onewire_byte_out( 0x44); // perform temperature conversion
pairmand 3:8f2b7f4940b5 268 if (_parasite_power) {
pairmand 3:8f2b7f4940b5 269 _parasitepin = 1; // Parasite power strong pullup
pairmand 3:8f2b7f4940b5 270 wait_ms(delay_time);
pairmand 3:8f2b7f4940b5 271 _parasitepin = 0;
pairmand 3:8f2b7f4940b5 272 delay_time = 0;
pairmand 3:8f2b7f4940b5 273 } else {
pairmand 3:8f2b7f4940b5 274 if (wait) {
pairmand 3:8f2b7f4940b5 275 wait_ms(delay_time);
pairmand 3:8f2b7f4940b5 276 delay_time = 0;
pairmand 3:8f2b7f4940b5 277 }
pairmand 3:8f2b7f4940b5 278 }
pairmand 3:8f2b7f4940b5 279 return delay_time;
pairmand 3:8f2b7f4940b5 280 }
pairmand 3:8f2b7f4940b5 281
pairmand 3:8f2b7f4940b5 282 void DS1820::read_RAM() {
pairmand 3:8f2b7f4940b5 283 // This will copy the DS1820's 9 bytes of RAM data
pairmand 3:8f2b7f4940b5 284 // into the objects RAM array. Functions that use
pairmand 3:8f2b7f4940b5 285 // RAM values will automaticly call this procedure.
pairmand 3:8f2b7f4940b5 286 int i;
pairmand 3:8f2b7f4940b5 287 match_ROM(); // Select this device
pairmand 3:8f2b7f4940b5 288 onewire_byte_out( 0xBE); //Read Scratchpad command
pairmand 3:8f2b7f4940b5 289 for(i=0;i<9;i++) {
pairmand 3:8f2b7f4940b5 290 RAM[i] = onewire_byte_in();
pairmand 3:8f2b7f4940b5 291 }
pairmand 3:8f2b7f4940b5 292 // if (!RAM_checksum_error())
pairmand 3:8f2b7f4940b5 293 // crcerr = 1;
pairmand 3:8f2b7f4940b5 294 }
pairmand 3:8f2b7f4940b5 295
pairmand 3:8f2b7f4940b5 296 bool DS1820::set_configuration_bits(unsigned int resolution) {
pairmand 3:8f2b7f4940b5 297 bool answer = false;
pairmand 3:8f2b7f4940b5 298 resolution = resolution - 9;
pairmand 3:8f2b7f4940b5 299 if (resolution < 4) {
pairmand 3:8f2b7f4940b5 300 resolution = resolution<<5; // align the bits
pairmand 3:8f2b7f4940b5 301 RAM[4] = (RAM[4] & 0x60) | resolution; // mask out old data, insert new
pairmand 3:8f2b7f4940b5 302 write_scratchpad ((RAM[2]<<8) + RAM[3]);
pairmand 3:8f2b7f4940b5 303 // store_scratchpad (DS1820::this_device); // Need to test if this is required
pairmand 3:8f2b7f4940b5 304 answer = true;
pairmand 3:8f2b7f4940b5 305 }
pairmand 3:8f2b7f4940b5 306 return answer;
pairmand 3:8f2b7f4940b5 307 }
pairmand 3:8f2b7f4940b5 308
pairmand 3:8f2b7f4940b5 309 int DS1820::read_scratchpad() {
pairmand 3:8f2b7f4940b5 310 int answer;
pairmand 3:8f2b7f4940b5 311 read_RAM();
pairmand 3:8f2b7f4940b5 312 answer = (RAM[2]<<8) + RAM[3];
pairmand 3:8f2b7f4940b5 313 return answer;
pairmand 3:8f2b7f4940b5 314 }
pairmand 3:8f2b7f4940b5 315
pairmand 3:8f2b7f4940b5 316 void DS1820::write_scratchpad(int data) {
pairmand 3:8f2b7f4940b5 317 RAM[3] = data;
pairmand 3:8f2b7f4940b5 318 RAM[2] = data>>8;
pairmand 3:8f2b7f4940b5 319 match_ROM();
pairmand 3:8f2b7f4940b5 320 onewire_byte_out(0x4E); // Copy scratchpad into DS1820 ram memory
pairmand 3:8f2b7f4940b5 321 onewire_byte_out(RAM[2]); // T(H)
pairmand 3:8f2b7f4940b5 322 onewire_byte_out(RAM[3]); // T(L)
pairmand 3:8f2b7f4940b5 323 if ( FAMILY_CODE == FAMILY_CODE_DS18B20 ) {
pairmand 3:8f2b7f4940b5 324 onewire_byte_out(RAM[4]); // Configuration register
pairmand 3:8f2b7f4940b5 325 }
pairmand 3:8f2b7f4940b5 326 }
pairmand 3:8f2b7f4940b5 327
pairmand 3:8f2b7f4940b5 328 void DS1820::store_scratchpad(devices device) {
pairmand 3:8f2b7f4940b5 329 if (device==all_devices)
pairmand 3:8f2b7f4940b5 330 skip_ROM(); // Skip ROM command, will store for ALL devices
pairmand 3:8f2b7f4940b5 331 else
pairmand 3:8f2b7f4940b5 332 match_ROM();
pairmand 3:8f2b7f4940b5 333 onewire_byte_out(0x48); // Write scratchpad into E2 command
pairmand 3:8f2b7f4940b5 334 if (_parasite_power)
pairmand 3:8f2b7f4940b5 335 _parasitepin=1;
pairmand 3:8f2b7f4940b5 336 wait_ms(10); // Parasite power strong pullup for 10ms
pairmand 3:8f2b7f4940b5 337 if (_parasite_power)
pairmand 3:8f2b7f4940b5 338 _parasitepin=0;
pairmand 3:8f2b7f4940b5 339 }
pairmand 3:8f2b7f4940b5 340
pairmand 3:8f2b7f4940b5 341 int DS1820::recall_scratchpad(devices device) {
pairmand 3:8f2b7f4940b5 342 // This copies the E2 values into the DS1820's memory.
pairmand 3:8f2b7f4940b5 343 // If you specify all_devices this will return zero, otherwise
pairmand 3:8f2b7f4940b5 344 // it will return the value of the scratchpad memory.
pairmand 3:8f2b7f4940b5 345 int answer=0;
pairmand 3:8f2b7f4940b5 346 if (device==all_devices)
pairmand 3:8f2b7f4940b5 347 skip_ROM(); // Skip ROM command, will recall for ALL devices
pairmand 3:8f2b7f4940b5 348 else
pairmand 3:8f2b7f4940b5 349 match_ROM();
pairmand 3:8f2b7f4940b5 350 onewire_byte_out(0xB8); // Recall E2 data to scratchpad command
pairmand 3:8f2b7f4940b5 351 wait_ms(10); // not sure I like polling for completion
pairmand 3:8f2b7f4940b5 352 // it could cause an infinite loop
pairmand 3:8f2b7f4940b5 353 if (device==DS1820::this_device) {
pairmand 3:8f2b7f4940b5 354 read_RAM();
pairmand 3:8f2b7f4940b5 355 answer = read_scratchpad();
pairmand 3:8f2b7f4940b5 356 }
pairmand 3:8f2b7f4940b5 357 return answer;
pairmand 3:8f2b7f4940b5 358 }
pairmand 3:8f2b7f4940b5 359
pairmand 3:8f2b7f4940b5 360 float DS1820::temperature(char scale) {
pairmand 3:8f2b7f4940b5 361 // The data specs state that count_per_degree should be 0x10 (16), I found my devices
pairmand 3:8f2b7f4940b5 362 // to have a count_per_degree of 0x4B (75). With the standard resolution of 1/2 deg C
pairmand 3:8f2b7f4940b5 363 // this allowed an expanded resolution of 1/150th of a deg C. I wouldn't rely on this
pairmand 3:8f2b7f4940b5 364 // being super acurate, but it does allow for a smooth display in the 1/10ths of a
pairmand 3:8f2b7f4940b5 365 // deg C or F scales.
pairmand 3:8f2b7f4940b5 366 float answer, remaining_count, count_per_degree;
pairmand 3:8f2b7f4940b5 367 int reading;
pairmand 3:8f2b7f4940b5 368 read_RAM();
pairmand 3:8f2b7f4940b5 369 if (RAM_checksum_error())
pairmand 3:8f2b7f4940b5 370 // Indicate we got a CRC error
pairmand 3:8f2b7f4940b5 371 answer = -1000.0;
pairmand 3:8f2b7f4940b5 372 else {
pairmand 3:8f2b7f4940b5 373 reading = (RAM[1] << 8) + RAM[0];
pairmand 3:8f2b7f4940b5 374 if (reading & 0x8000) { // negative degrees C
pairmand 3:8f2b7f4940b5 375 reading = 0-((reading ^ 0xffff) + 1); // 2's comp then convert to signed int
pairmand 3:8f2b7f4940b5 376 }
pairmand 3:8f2b7f4940b5 377 answer = reading +0.0; // convert to floating point
pairmand 3:8f2b7f4940b5 378 if ( FAMILY_CODE == FAMILY_CODE_DS18B20 ) {
pairmand 3:8f2b7f4940b5 379 answer = answer / 8.0;
pairmand 3:8f2b7f4940b5 380 }
pairmand 3:8f2b7f4940b5 381 else {
pairmand 3:8f2b7f4940b5 382 remaining_count = RAM[6];
pairmand 3:8f2b7f4940b5 383 count_per_degree = RAM[7];
pairmand 3:8f2b7f4940b5 384 answer = answer - 0.25 + (count_per_degree - remaining_count) / count_per_degree;
pairmand 3:8f2b7f4940b5 385 }
pairmand 3:8f2b7f4940b5 386 if (scale=='C' or scale=='c')
pairmand 3:8f2b7f4940b5 387 answer = answer / 2.0;
pairmand 3:8f2b7f4940b5 388 else
pairmand 3:8f2b7f4940b5 389 // Convert to deg F
pairmand 3:8f2b7f4940b5 390 answer = answer * 9.0 / 10.0 + 32.0;
pairmand 3:8f2b7f4940b5 391 }
pairmand 3:8f2b7f4940b5 392 return answer;
pairmand 3:8f2b7f4940b5 393 }
pairmand 3:8f2b7f4940b5 394
pairmand 3:8f2b7f4940b5 395 bool DS1820::read_power_supply(devices device) {
pairmand 3:8f2b7f4940b5 396 // This will return true if the device (or all devices) are Vcc powered
pairmand 3:8f2b7f4940b5 397 // This will return false if the device (or ANY device) is parasite powered
pairmand 3:8f2b7f4940b5 398 if (device==all_devices)
pairmand 3:8f2b7f4940b5 399 skip_ROM(); // Skip ROM command, will poll for any device using parasite power
pairmand 3:8f2b7f4940b5 400 else
pairmand 3:8f2b7f4940b5 401 match_ROM();
pairmand 3:8f2b7f4940b5 402 onewire_byte_out(0xB4); // Read power supply command
pairmand 3:8f2b7f4940b5 403 return onewire_bit_in();
pairmand 3:8f2b7f4940b5 404 }
pairmand 3:8f2b7f4940b5 405
pairmand 3:8f2b7f4940b5 406