Glimworm Beacons / DS1820

Realtime

Fork of DS1820 by David Pairman

DS1820.cpp@5:f77b9f69df9e, 2016-10-09 (annotated)

Committer:
GlimwormBeacons
Date:
Sun Oct 09 09:45:34 2016 +0000
Revision:
5:f77b9f69df9e
Parent:
4:29264b0a2c9f 
made it real time for nrf51822 using nrf_delay_us instead of timer

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
GlimwormBeacons 5:f77b9f69df9e 9
GlimwormBeacons 5:f77b9f69df9e 10
GlimwormBeacons 5:f77b9f69df9e 11
GlimwormBeacons 5:f77b9f69df9e 12 #if defined ( __CC_ARM )
GlimwormBeacons 5:f77b9f69df9e 13 static __ASM void __INLINE nrf_delay_us(uint32_t volatile number_of_us)
GlimwormBeacons 5:f77b9f69df9e 14 {
GlimwormBeacons 5:f77b9f69df9e 15 loop
GlimwormBeacons 5:f77b9f69df9e 16 SUBS R0, R0, #1
GlimwormBeacons 5:f77b9f69df9e 17 NOP
GlimwormBeacons 5:f77b9f69df9e 18 NOP
GlimwormBeacons 5:f77b9f69df9e 19 NOP
GlimwormBeacons 5:f77b9f69df9e 20 NOP
GlimwormBeacons 5:f77b9f69df9e 21 NOP
GlimwormBeacons 5:f77b9f69df9e 22 NOP
GlimwormBeacons 5:f77b9f69df9e 23 NOP
GlimwormBeacons 5:f77b9f69df9e 24 NOP
GlimwormBeacons 5:f77b9f69df9e 25 NOP
GlimwormBeacons 5:f77b9f69df9e 26 NOP
GlimwormBeacons 5:f77b9f69df9e 27 NOP
GlimwormBeacons 5:f77b9f69df9e 28 NOP
GlimwormBeacons 5:f77b9f69df9e 29 BNE loop
GlimwormBeacons 5:f77b9f69df9e 30 BX LR
GlimwormBeacons 5:f77b9f69df9e 31 }
GlimwormBeacons 5:f77b9f69df9e 32 #elif defined ( __ICCARM__ )
GlimwormBeacons 5:f77b9f69df9e 33 static void __INLINE nrf_delay_us(uint32_t volatile number_of_us)
GlimwormBeacons 5:f77b9f69df9e 34 {
GlimwormBeacons 5:f77b9f69df9e 35 __ASM (
GlimwormBeacons 5:f77b9f69df9e 36 "loop:\n\t"
GlimwormBeacons 5:f77b9f69df9e 37 " SUBS R0, R0, #1\n\t"
GlimwormBeacons 5:f77b9f69df9e 38 " NOP\n\t"
GlimwormBeacons 5:f77b9f69df9e 39 " NOP\n\t"
GlimwormBeacons 5:f77b9f69df9e 40 " NOP\n\t"
GlimwormBeacons 5:f77b9f69df9e 41 " NOP\n\t"
GlimwormBeacons 5:f77b9f69df9e 42 " NOP\n\t"
GlimwormBeacons 5:f77b9f69df9e 43 " NOP\n\t"
GlimwormBeacons 5:f77b9f69df9e 44 " NOP\n\t"
GlimwormBeacons 5:f77b9f69df9e 45 " NOP\n\t"
GlimwormBeacons 5:f77b9f69df9e 46 " NOP\n\t"
GlimwormBeacons 5:f77b9f69df9e 47 " NOP\n\t"
GlimwormBeacons 5:f77b9f69df9e 48 " NOP\n\t"
GlimwormBeacons 5:f77b9f69df9e 49 " NOP\n\t"
GlimwormBeacons 5:f77b9f69df9e 50 " BNE loop\n\t");
GlimwormBeacons 5:f77b9f69df9e 51 }
GlimwormBeacons 5:f77b9f69df9e 52 #elif defined ( __GNUC__ )
GlimwormBeacons 5:f77b9f69df9e 53 __INLINE static void nrf_delay_us(uint32_t volatile number_of_us)
GlimwormBeacons 5:f77b9f69df9e 54 {
GlimwormBeacons 5:f77b9f69df9e 55 do
GlimwormBeacons 5:f77b9f69df9e 56 {
GlimwormBeacons 5:f77b9f69df9e 57 __ASM volatile (
GlimwormBeacons 5:f77b9f69df9e 58 "NOP\n\t"
GlimwormBeacons 5:f77b9f69df9e 59 "NOP\n\t"
GlimwormBeacons 5:f77b9f69df9e 60 "NOP\n\t"
GlimwormBeacons 5:f77b9f69df9e 61 "NOP\n\t"
GlimwormBeacons 5:f77b9f69df9e 62 "NOP\n\t"
GlimwormBeacons 5:f77b9f69df9e 63 "NOP\n\t"
GlimwormBeacons 5:f77b9f69df9e 64 "NOP\n\t"
GlimwormBeacons 5:f77b9f69df9e 65 "NOP\n\t"
GlimwormBeacons 5:f77b9f69df9e 66 "NOP\n\t"
GlimwormBeacons 5:f77b9f69df9e 67 "NOP\n\t"
GlimwormBeacons 5:f77b9f69df9e 68 "NOP\n\t"
GlimwormBeacons 5:f77b9f69df9e 69 "NOP\n\t"
GlimwormBeacons 5:f77b9f69df9e 70 "NOP\n\t"
GlimwormBeacons 5:f77b9f69df9e 71 "NOP\n\t"
GlimwormBeacons 5:f77b9f69df9e 72 );
GlimwormBeacons 5:f77b9f69df9e 73 } while (--number_of_us);
GlimwormBeacons 5:f77b9f69df9e 74 }
GlimwormBeacons 5:f77b9f69df9e 75 #endif
pairmand 3:8f2b7f4940b5 76
pairmand 3:8f2b7f4940b5 77 DS1820::DS1820 (PinName data_pin, PinName power_pin) : _datapin(data_pin), _parasitepin(power_pin) {
pairmand 3:8f2b7f4940b5 78 int byte_counter;
pairmand 3:8f2b7f4940b5 79 _parasite_power = true;
pairmand 3:8f2b7f4940b5 80 for(byte_counter=0;byte_counter<8;byte_counter++)
pairmand 3:8f2b7f4940b5 81 ROM[byte_counter] = 0xFF;
pairmand 3:8f2b7f4940b5 82 for(byte_counter=0;byte_counter<9;byte_counter++)
pairmand 3:8f2b7f4940b5 83 RAM[byte_counter] = 0x00;
pairmand 3:8f2b7f4940b5 84 }
pairmand 3:8f2b7f4940b5 85 DS1820::DS1820 (PinName data_pin) : _datapin(data_pin), _parasitepin(NC) {
pairmand 3:8f2b7f4940b5 86 int byte_counter;
pairmand 3:8f2b7f4940b5 87 _parasite_power = false;
pairmand 3:8f2b7f4940b5 88 for(byte_counter=0;byte_counter<8;byte_counter++)
pairmand 3:8f2b7f4940b5 89 ROM[byte_counter] = 0xFF;
pairmand 3:8f2b7f4940b5 90 for(byte_counter=0;byte_counter<9;byte_counter++)
pairmand 3:8f2b7f4940b5 91 RAM[byte_counter] = 0x00;
pairmand 3:8f2b7f4940b5 92 }
pairmand 3:8f2b7f4940b5 93
pairmand 3:8f2b7f4940b5 94 bool DS1820::onewire_reset() {
pairmand 3:8f2b7f4940b5 95 // This will return false if no devices are present on the data bus
pairmand 3:8f2b7f4940b5 96 bool presence=false;
pairmand 3:8f2b7f4940b5 97 _datapin.output();
pairmand 3:8f2b7f4940b5 98 _datapin = 0; // bring low for 500 us
GlimwormBeacons 5:f77b9f69df9e 99 nrf_delay_us(500);
pairmand 3:8f2b7f4940b5 100 _datapin.input(); // let the data line float high
GlimwormBeacons 5:f77b9f69df9e 101 nrf_delay_us(90); // wait 90us
pairmand 3:8f2b7f4940b5 102 if (_datapin.read()==0) // see if any devices are pulling the data line low
pairmand 3:8f2b7f4940b5 103 presence=true;
GlimwormBeacons 5:f77b9f69df9e 104 nrf_delay_us(410);
pairmand 3:8f2b7f4940b5 105 return presence;
pairmand 3:8f2b7f4940b5 106 }
pairmand 3:8f2b7f4940b5 107
pairmand 3:8f2b7f4940b5 108 void DS1820::onewire_bit_out (bool bit_data) {
pairmand 3:8f2b7f4940b5 109 _datapin.output();
pairmand 3:8f2b7f4940b5 110 _datapin = 0;
GlimwormBeacons 5:f77b9f69df9e 111 nrf_delay_us(3); // DXP modified from 5
pairmand 3:8f2b7f4940b5 112 if (bit_data) {
pairmand 3:8f2b7f4940b5 113 _datapin.input(); // bring data line high
GlimwormBeacons 5:f77b9f69df9e 114 nrf_delay_us(55);
pairmand 3:8f2b7f4940b5 115 } else {
GlimwormBeacons 5:f77b9f69df9e 116 nrf_delay_us(55); // keep data line low
pairmand 3:8f2b7f4940b5 117 _datapin.input();
GlimwormBeacons 5:f77b9f69df9e 118 nrf_delay_us(10); // DXP added to allow bus to float high before next bit_out
pairmand 3:8f2b7f4940b5 119 }
pairmand 3:8f2b7f4940b5 120 }
pairmand 3:8f2b7f4940b5 121
pairmand 3:8f2b7f4940b5 122 void DS1820::onewire_byte_out(char data) { // output data character (least sig bit first).
pairmand 3:8f2b7f4940b5 123 int n;
pairmand 3:8f2b7f4940b5 124 for (n=0; n<8; n++) {
pairmand 3:8f2b7f4940b5 125 onewire_bit_out(data & 0x01);
pairmand 3:8f2b7f4940b5 126 data = data >> 1; // now the next bit is in the least sig bit position.
pairmand 3:8f2b7f4940b5 127 }
pairmand 3:8f2b7f4940b5 128 }
pairmand 3:8f2b7f4940b5 129
pairmand 3:8f2b7f4940b5 130 bool DS1820::onewire_bit_in() {
pairmand 3:8f2b7f4940b5 131 bool answer;
pairmand 3:8f2b7f4940b5 132 _datapin.output();
pairmand 3:8f2b7f4940b5 133 _datapin = 0;
GlimwormBeacons 5:f77b9f69df9e 134 nrf_delay_us(3); // DXP modofied from 5
pairmand 3:8f2b7f4940b5 135 _datapin.input();
GlimwormBeacons 5:f77b9f69df9e 136 nrf_delay_us(10); // DXP modified from 5
pairmand 3:8f2b7f4940b5 137 answer = _datapin.read();
GlimwormBeacons 5:f77b9f69df9e 138 nrf_delay_us(45); // DXP modified from 50
pairmand 3:8f2b7f4940b5 139 return answer;
pairmand 3:8f2b7f4940b5 140 }
pairmand 3:8f2b7f4940b5 141
pairmand 3:8f2b7f4940b5 142 char DS1820::onewire_byte_in() { // read byte, least sig byte first
pairmand 3:8f2b7f4940b5 143 char answer = 0x00;
pairmand 3:8f2b7f4940b5 144 int i;
pairmand 3:8f2b7f4940b5 145 for (i=0; i<8; i++) {
pairmand 3:8f2b7f4940b5 146 answer = answer >> 1; // shift over to make room for the next bit
pairmand 3:8f2b7f4940b5 147 if (onewire_bit_in())
pairmand 3:8f2b7f4940b5 148 answer = answer | 0x80; // if the data port is high, make this bit a 1
pairmand 3:8f2b7f4940b5 149 }
pairmand 3:8f2b7f4940b5 150 return answer;
pairmand 3:8f2b7f4940b5 151 }
pairmand 3:8f2b7f4940b5 152
pairmand 3:8f2b7f4940b5 153 bool DS1820::search_ROM() {
pairmand 3:8f2b7f4940b5 154 return search_ROM_routine(0xF0); // Search ROM command
pairmand 3:8f2b7f4940b5 155 }
pairmand 3:8f2b7f4940b5 156
pairmand 3:8f2b7f4940b5 157 bool DS1820::search_alarm() {
pairmand 3:8f2b7f4940b5 158 return search_ROM_routine(0xEC); // Search Alarm command
pairmand 3:8f2b7f4940b5 159 }
pairmand 3:8f2b7f4940b5 160
pairmand 3:8f2b7f4940b5 161 bool DS1820::search_ROM_routine(char command) {
pairmand 3:8f2b7f4940b5 162 extern bool DS1820_done_flag;
pairmand 3:8f2b7f4940b5 163 extern int DS1820_last_descrepancy;
pairmand 3:8f2b7f4940b5 164 extern char DS1820_search_ROM[8];
pairmand 3:8f2b7f4940b5 165 int descrepancy_marker, ROM_bit_index;
pairmand 3:8f2b7f4940b5 166 bool return_value, Bit_A, Bit_B;
pairmand 3:8f2b7f4940b5 167 char byte_counter, bit_mask;
pairmand 3:8f2b7f4940b5 168
pairmand 3:8f2b7f4940b5 169 return_value=false;
pairmand 3:8f2b7f4940b5 170 if (!DS1820_done_flag) {
pairmand 3:8f2b7f4940b5 171 if (!onewire_reset()) {
pairmand 3:8f2b7f4940b5 172 DS1820_last_descrepancy = 0; // no devices present
pairmand 3:8f2b7f4940b5 173 } else {
pairmand 3:8f2b7f4940b5 174 ROM_bit_index=1;
pairmand 3:8f2b7f4940b5 175 descrepancy_marker=0;
pairmand 3:8f2b7f4940b5 176 onewire_byte_out(command); // Search ROM command or Search Alarm command
pairmand 3:8f2b7f4940b5 177 byte_counter = 0;
pairmand 3:8f2b7f4940b5 178 bit_mask = 0x01;
pairmand 3:8f2b7f4940b5 179 while (ROM_bit_index<=64) {
pairmand 3:8f2b7f4940b5 180 Bit_A = onewire_bit_in();
pairmand 3:8f2b7f4940b5 181 Bit_B = onewire_bit_in();
pairmand 3:8f2b7f4940b5 182 if (Bit_A & Bit_B) {
pairmand 3:8f2b7f4940b5 183 descrepancy_marker = 0; // data read error, this should never happen
pairmand 3:8f2b7f4940b5 184 ROM_bit_index = 0xFF;
pairmand 3:8f2b7f4940b5 185 } else {
pairmand 3:8f2b7f4940b5 186 if (Bit_A | Bit_B) {
pairmand 3:8f2b7f4940b5 187 // Set ROM bit to Bit_A
pairmand 3:8f2b7f4940b5 188 if (Bit_A) {
pairmand 3:8f2b7f4940b5 189 DS1820_search_ROM[byte_counter] = DS1820_search_ROM[byte_counter] | bit_mask; // Set ROM bit to one
pairmand 3:8f2b7f4940b5 190 } else {
pairmand 3:8f2b7f4940b5 191 DS1820_search_ROM[byte_counter] = DS1820_search_ROM[byte_counter] & ~bit_mask; // Set ROM bit to zero
pairmand 3:8f2b7f4940b5 192 }
pairmand 3:8f2b7f4940b5 193 } else {
pairmand 3:8f2b7f4940b5 194 // both bits A and B are low, so there are two or more devices present
pairmand 3:8f2b7f4940b5 195 if ( ROM_bit_index == DS1820_last_descrepancy ) {
pairmand 3:8f2b7f4940b5 196 DS1820_search_ROM[byte_counter] = DS1820_search_ROM[byte_counter] | bit_mask; // Set ROM bit to one
pairmand 3:8f2b7f4940b5 197 } else {
pairmand 3:8f2b7f4940b5 198 if ( ROM_bit_index > DS1820_last_descrepancy ) {
pairmand 3:8f2b7f4940b5 199 DS1820_search_ROM[byte_counter] = DS1820_search_ROM[byte_counter] & ~bit_mask; // Set ROM bit to zero
pairmand 3:8f2b7f4940b5 200 descrepancy_marker = ROM_bit_index;
pairmand 3:8f2b7f4940b5 201 } else {
pairmand 3:8f2b7f4940b5 202 if (( DS1820_search_ROM[byte_counter] & bit_mask) == 0x00 )
pairmand 3:8f2b7f4940b5 203 descrepancy_marker = ROM_bit_index;
pairmand 3:8f2b7f4940b5 204 }
pairmand 3:8f2b7f4940b5 205 }
pairmand 3:8f2b7f4940b5 206 }
pairmand 3:8f2b7f4940b5 207 onewire_bit_out (DS1820_search_ROM[byte_counter] & bit_mask);
pairmand 3:8f2b7f4940b5 208 ROM_bit_index++;
pairmand 3:8f2b7f4940b5 209 if (bit_mask & 0x80) {
pairmand 3:8f2b7f4940b5 210 byte_counter++;
pairmand 3:8f2b7f4940b5 211 bit_mask = 0x01;
pairmand 3:8f2b7f4940b5 212 } else {
pairmand 3:8f2b7f4940b5 213 bit_mask = bit_mask << 1;
pairmand 3:8f2b7f4940b5 214 }
pairmand 3:8f2b7f4940b5 215 }
pairmand 3:8f2b7f4940b5 216 }
pairmand 3:8f2b7f4940b5 217 DS1820_last_descrepancy = descrepancy_marker;
pairmand 3:8f2b7f4940b5 218 if (ROM_bit_index != 0xFF) {
pairmand 3:8f2b7f4940b5 219 for(byte_counter=0;byte_counter<8;byte_counter++)
pairmand 3:8f2b7f4940b5 220 ROM[byte_counter] = DS1820_search_ROM[byte_counter];
pairmand 4:29264b0a2c9f 221 if (ROM_checksum_error()) // Check the CRC
pairmand 4:29264b0a2c9f 222 DS1820_last_descrepancy = 0; // Abort any more search
pairmand 4:29264b0a2c9f 223 else
pairmand 4:29264b0a2c9f 224 return_value = true;
pairmand 3:8f2b7f4940b5 225 }
pairmand 3:8f2b7f4940b5 226 }
pairmand 3:8f2b7f4940b5 227 if (DS1820_last_descrepancy == 0)
pairmand 3:8f2b7f4940b5 228 DS1820_done_flag = true;
pairmand 3:8f2b7f4940b5 229 }
pairmand 3:8f2b7f4940b5 230 return return_value;
pairmand 3:8f2b7f4940b5 231 }
pairmand 3:8f2b7f4940b5 232
pairmand 3:8f2b7f4940b5 233 void DS1820::search_ROM_setup() {
pairmand 3:8f2b7f4940b5 234 extern bool DS1820_done_flag;
pairmand 3:8f2b7f4940b5 235 extern int DS1820_last_descrepancy;
pairmand 3:8f2b7f4940b5 236 extern char DS1820_search_ROM[8];
pairmand 3:8f2b7f4940b5 237 DS1820_done_flag = false;
pairmand 3:8f2b7f4940b5 238 DS1820_last_descrepancy = 0;
pairmand 3:8f2b7f4940b5 239 int i;
pairmand 3:8f2b7f4940b5 240 for (i=0; i<8; i++)
pairmand 3:8f2b7f4940b5 241 DS1820_search_ROM[i]=0x00;
pairmand 3:8f2b7f4940b5 242 }
pairmand 3:8f2b7f4940b5 243
pairmand 3:8f2b7f4940b5 244 void DS1820::read_ROM() {
pairmand 3:8f2b7f4940b5 245 // NOTE: This command can only be used when there is one DS1820 on the bus. If this command
pairmand 3:8f2b7f4940b5 246 // is used when there is more than one slave present on the bus, a data collision will occur
pairmand 3:8f2b7f4940b5 247 // when all the DS1820s attempt to respond at the same time.
pairmand 3:8f2b7f4940b5 248 int i;
pairmand 3:8f2b7f4940b5 249 onewire_reset();
pairmand 3:8f2b7f4940b5 250 onewire_byte_out(0x33); // Read ROM id
pairmand 3:8f2b7f4940b5 251 for (i=0; i<8; i++)
pairmand 3:8f2b7f4940b5 252 ROM[i]=onewire_byte_in();
pairmand 3:8f2b7f4940b5 253 }
pairmand 3:8f2b7f4940b5 254
pairmand 3:8f2b7f4940b5 255 void DS1820::match_ROM() {
pairmand 3:8f2b7f4940b5 256 // Used to select a specific device
pairmand 3:8f2b7f4940b5 257 int i;
pairmand 3:8f2b7f4940b5 258 onewire_reset();
pairmand 3:8f2b7f4940b5 259 onewire_byte_out( 0x55); //Match ROM command
pairmand 3:8f2b7f4940b5 260 for (i=0;i<8;i++)
pairmand 3:8f2b7f4940b5 261 onewire_byte_out(ROM[i]);
pairmand 3:8f2b7f4940b5 262 }
pairmand 3:8f2b7f4940b5 263
pairmand 3:8f2b7f4940b5 264 void DS1820::skip_ROM() {
pairmand 3:8f2b7f4940b5 265 onewire_reset();
pairmand 3:8f2b7f4940b5 266 onewire_byte_out(0xCC); // Skip ROM command
pairmand 3:8f2b7f4940b5 267 }
pairmand 3:8f2b7f4940b5 268
pairmand 3:8f2b7f4940b5 269 bool DS1820::ROM_checksum_error() {
pairmand 3:8f2b7f4940b5 270 char CRC=0x00;
pairmand 3:8f2b7f4940b5 271 int i;
pairmand 3:8f2b7f4940b5 272 for(i=0;i<7;i++) // Only going to shift the lower 7 bytes
pairmand 3:8f2b7f4940b5 273 CRC = CRC_byte(CRC, ROM[i]);
pairmand 3:8f2b7f4940b5 274 // After 7 bytes CRC should equal the 8th byte (ROM CRC)
pairmand 3:8f2b7f4940b5 275 return (CRC!=ROM[7]); // will return true if there is a CRC checksum mis-match
pairmand 3:8f2b7f4940b5 276 }
pairmand 3:8f2b7f4940b5 277
pairmand 3:8f2b7f4940b5 278 bool DS1820::RAM_checksum_error() {
pairmand 3:8f2b7f4940b5 279 char CRC=0x00;
pairmand 3:8f2b7f4940b5 280 int i;
pairmand 3:8f2b7f4940b5 281 for(i=0;i<8;i++) // Only going to shift the lower 8 bytes
pairmand 3:8f2b7f4940b5 282 CRC = CRC_byte(CRC, RAM[i]);
pairmand 3:8f2b7f4940b5 283 // After 8 bytes CRC should equal the 9th byte (RAM CRC)
pairmand 3:8f2b7f4940b5 284 return (CRC!=RAM[8]); // will return true if there is a CRC checksum mis-match
pairmand 3:8f2b7f4940b5 285 }
pairmand 3:8f2b7f4940b5 286
pairmand 3:8f2b7f4940b5 287 char DS1820::CRC_byte (char CRC, char byte ) {
pairmand 3:8f2b7f4940b5 288 int j;
pairmand 3:8f2b7f4940b5 289 for(j=0;j<8;j++) {
pairmand 3:8f2b7f4940b5 290 if ((byte & 0x01 ) ^ (CRC & 0x01)) {
pairmand 3:8f2b7f4940b5 291 // DATA ^ LSB CRC = 1
pairmand 3:8f2b7f4940b5 292 CRC = CRC>>1;
pairmand 3:8f2b7f4940b5 293 // Set the MSB to 1
pairmand 3:8f2b7f4940b5 294 CRC = CRC | 0x80;
pairmand 3:8f2b7f4940b5 295 // Check bit 3
pairmand 3:8f2b7f4940b5 296 if (CRC & 0x04) {
pairmand 3:8f2b7f4940b5 297 CRC = CRC & 0xFB; // Bit 3 is set, so clear it
pairmand 3:8f2b7f4940b5 298 } else {
pairmand 3:8f2b7f4940b5 299 CRC = CRC | 0x04; // Bit 3 is clear, so set it
pairmand 3:8f2b7f4940b5 300 }
pairmand 3:8f2b7f4940b5 301 // Check bit 4
pairmand 3:8f2b7f4940b5 302 if (CRC & 0x08) {
pairmand 3:8f2b7f4940b5 303 CRC = CRC & 0xF7; // Bit 4 is set, so clear it
pairmand 3:8f2b7f4940b5 304 } else {
pairmand 3:8f2b7f4940b5 305 CRC = CRC | 0x08; // Bit 4 is clear, so set it
pairmand 3:8f2b7f4940b5 306 }
pairmand 3:8f2b7f4940b5 307 } else {
pairmand 3:8f2b7f4940b5 308 // DATA ^ LSB CRC = 0
pairmand 3:8f2b7f4940b5 309 CRC = CRC>>1;
pairmand 3:8f2b7f4940b5 310 // clear MSB
pairmand 3:8f2b7f4940b5 311 CRC = CRC & 0x7F;
pairmand 3:8f2b7f4940b5 312 // No need to check bits, with DATA ^ LSB CRC = 0, they will remain unchanged
pairmand 3:8f2b7f4940b5 313 }
pairmand 3:8f2b7f4940b5 314 byte = byte>>1;
pairmand 3:8f2b7f4940b5 315 }
pairmand 3:8f2b7f4940b5 316 return CRC;
pairmand 3:8f2b7f4940b5 317 }
pairmand 3:8f2b7f4940b5 318
pairmand 3:8f2b7f4940b5 319 int DS1820::convert_temperature(bool wait, devices device) {
pairmand 3:8f2b7f4940b5 320 // Convert temperature into scratchpad RAM for all devices at once
pairmand 3:8f2b7f4940b5 321 int delay_time = 750; // Default delay time
pairmand 3:8f2b7f4940b5 322 char resolution;
pairmand 3:8f2b7f4940b5 323 if (device==all_devices)
pairmand 3:8f2b7f4940b5 324 skip_ROM(); // Skip ROM command, will convert for ALL devices
pairmand 3:8f2b7f4940b5 325 else {
pairmand 3:8f2b7f4940b5 326 match_ROM();
pairmand 3:8f2b7f4940b5 327 if (FAMILY_CODE == FAMILY_CODE_DS18B20 ) {
pairmand 3:8f2b7f4940b5 328 resolution = RAM[4] & 0x60;
pairmand 3:8f2b7f4940b5 329 if (resolution == 0x00) // 9 bits
pairmand 3:8f2b7f4940b5 330 delay_time = 94;
pairmand 3:8f2b7f4940b5 331 if (resolution == 0x20) // 10 bits
pairmand 3:8f2b7f4940b5 332 delay_time = 188;
pairmand 3:8f2b7f4940b5 333 if (resolution == 0x40) // 11 bits. Note 12bits uses the 750ms default
pairmand 3:8f2b7f4940b5 334 delay_time = 375;
pairmand 3:8f2b7f4940b5 335 }
pairmand 3:8f2b7f4940b5 336 }
pairmand 3:8f2b7f4940b5 337 onewire_byte_out( 0x44); // perform temperature conversion
pairmand 3:8f2b7f4940b5 338 if (_parasite_power) {
pairmand 3:8f2b7f4940b5 339 _parasitepin = 1; // Parasite power strong pullup
pairmand 3:8f2b7f4940b5 340 wait_ms(delay_time);
pairmand 3:8f2b7f4940b5 341 _parasitepin = 0;
pairmand 3:8f2b7f4940b5 342 delay_time = 0;
pairmand 3:8f2b7f4940b5 343 } else {
pairmand 3:8f2b7f4940b5 344 if (wait) {
pairmand 3:8f2b7f4940b5 345 wait_ms(delay_time);
pairmand 3:8f2b7f4940b5 346 delay_time = 0;
pairmand 3:8f2b7f4940b5 347 }
pairmand 3:8f2b7f4940b5 348 }
pairmand 3:8f2b7f4940b5 349 return delay_time;
pairmand 3:8f2b7f4940b5 350 }
pairmand 3:8f2b7f4940b5 351
pairmand 3:8f2b7f4940b5 352 void DS1820::read_RAM() {
pairmand 3:8f2b7f4940b5 353 // This will copy the DS1820's 9 bytes of RAM data
pairmand 3:8f2b7f4940b5 354 // into the objects RAM array. Functions that use
pairmand 3:8f2b7f4940b5 355 // RAM values will automaticly call this procedure.
pairmand 3:8f2b7f4940b5 356 int i;
pairmand 3:8f2b7f4940b5 357 match_ROM(); // Select this device
pairmand 3:8f2b7f4940b5 358 onewire_byte_out( 0xBE); //Read Scratchpad command
pairmand 3:8f2b7f4940b5 359 for(i=0;i<9;i++) {
pairmand 3:8f2b7f4940b5 360 RAM[i] = onewire_byte_in();
pairmand 3:8f2b7f4940b5 361 }
pairmand 3:8f2b7f4940b5 362 // if (!RAM_checksum_error())
pairmand 3:8f2b7f4940b5 363 // crcerr = 1;
pairmand 3:8f2b7f4940b5 364 }
pairmand 3:8f2b7f4940b5 365
pairmand 3:8f2b7f4940b5 366 bool DS1820::set_configuration_bits(unsigned int resolution) {
pairmand 3:8f2b7f4940b5 367 bool answer = false;
pairmand 3:8f2b7f4940b5 368 resolution = resolution - 9;
pairmand 3:8f2b7f4940b5 369 if (resolution < 4) {
pairmand 3:8f2b7f4940b5 370 resolution = resolution<<5; // align the bits
pairmand 3:8f2b7f4940b5 371 RAM[4] = (RAM[4] & 0x60) | resolution; // mask out old data, insert new
pairmand 3:8f2b7f4940b5 372 write_scratchpad ((RAM[2]<<8) + RAM[3]);
pairmand 3:8f2b7f4940b5 373 // store_scratchpad (DS1820::this_device); // Need to test if this is required
pairmand 3:8f2b7f4940b5 374 answer = true;
pairmand 3:8f2b7f4940b5 375 }
pairmand 3:8f2b7f4940b5 376 return answer;
pairmand 3:8f2b7f4940b5 377 }
pairmand 3:8f2b7f4940b5 378
pairmand 3:8f2b7f4940b5 379 int DS1820::read_scratchpad() {
pairmand 3:8f2b7f4940b5 380 int answer;
pairmand 3:8f2b7f4940b5 381 read_RAM();
pairmand 3:8f2b7f4940b5 382 answer = (RAM[2]<<8) + RAM[3];
pairmand 3:8f2b7f4940b5 383 return answer;
pairmand 3:8f2b7f4940b5 384 }
pairmand 3:8f2b7f4940b5 385
pairmand 3:8f2b7f4940b5 386 void DS1820::write_scratchpad(int data) {
pairmand 3:8f2b7f4940b5 387 RAM[3] = data;
pairmand 3:8f2b7f4940b5 388 RAM[2] = data>>8;
pairmand 3:8f2b7f4940b5 389 match_ROM();
pairmand 3:8f2b7f4940b5 390 onewire_byte_out(0x4E); // Copy scratchpad into DS1820 ram memory
pairmand 3:8f2b7f4940b5 391 onewire_byte_out(RAM[2]); // T(H)
pairmand 3:8f2b7f4940b5 392 onewire_byte_out(RAM[3]); // T(L)
pairmand 3:8f2b7f4940b5 393 if ( FAMILY_CODE == FAMILY_CODE_DS18B20 ) {
pairmand 3:8f2b7f4940b5 394 onewire_byte_out(RAM[4]); // Configuration register
pairmand 3:8f2b7f4940b5 395 }
pairmand 3:8f2b7f4940b5 396 }
pairmand 3:8f2b7f4940b5 397
pairmand 3:8f2b7f4940b5 398 void DS1820::store_scratchpad(devices device) {
pairmand 3:8f2b7f4940b5 399 if (device==all_devices)
pairmand 3:8f2b7f4940b5 400 skip_ROM(); // Skip ROM command, will store for ALL devices
pairmand 3:8f2b7f4940b5 401 else
pairmand 3:8f2b7f4940b5 402 match_ROM();
pairmand 3:8f2b7f4940b5 403 onewire_byte_out(0x48); // Write scratchpad into E2 command
pairmand 3:8f2b7f4940b5 404 if (_parasite_power)
pairmand 3:8f2b7f4940b5 405 _parasitepin=1;
pairmand 3:8f2b7f4940b5 406 wait_ms(10); // Parasite power strong pullup for 10ms
pairmand 3:8f2b7f4940b5 407 if (_parasite_power)
pairmand 3:8f2b7f4940b5 408 _parasitepin=0;
pairmand 3:8f2b7f4940b5 409 }
pairmand 3:8f2b7f4940b5 410
pairmand 3:8f2b7f4940b5 411 int DS1820::recall_scratchpad(devices device) {
pairmand 3:8f2b7f4940b5 412 // This copies the E2 values into the DS1820's memory.
pairmand 3:8f2b7f4940b5 413 // If you specify all_devices this will return zero, otherwise
pairmand 3:8f2b7f4940b5 414 // it will return the value of the scratchpad memory.
pairmand 3:8f2b7f4940b5 415 int answer=0;
pairmand 3:8f2b7f4940b5 416 if (device==all_devices)
pairmand 3:8f2b7f4940b5 417 skip_ROM(); // Skip ROM command, will recall for ALL devices
pairmand 3:8f2b7f4940b5 418 else
pairmand 3:8f2b7f4940b5 419 match_ROM();
pairmand 3:8f2b7f4940b5 420 onewire_byte_out(0xB8); // Recall E2 data to scratchpad command
pairmand 3:8f2b7f4940b5 421 wait_ms(10); // not sure I like polling for completion
pairmand 3:8f2b7f4940b5 422 // it could cause an infinite loop
pairmand 3:8f2b7f4940b5 423 if (device==DS1820::this_device) {
pairmand 3:8f2b7f4940b5 424 read_RAM();
pairmand 3:8f2b7f4940b5 425 answer = read_scratchpad();
pairmand 3:8f2b7f4940b5 426 }
pairmand 3:8f2b7f4940b5 427 return answer;
pairmand 3:8f2b7f4940b5 428 }
pairmand 3:8f2b7f4940b5 429
pairmand 3:8f2b7f4940b5 430 float DS1820::temperature(char scale) {
pairmand 3:8f2b7f4940b5 431 // The data specs state that count_per_degree should be 0x10 (16), I found my devices
pairmand 3:8f2b7f4940b5 432 // to have a count_per_degree of 0x4B (75). With the standard resolution of 1/2 deg C
pairmand 3:8f2b7f4940b5 433 // this allowed an expanded resolution of 1/150th of a deg C. I wouldn't rely on this
pairmand 3:8f2b7f4940b5 434 // being super acurate, but it does allow for a smooth display in the 1/10ths of a
pairmand 3:8f2b7f4940b5 435 // deg C or F scales.
pairmand 3:8f2b7f4940b5 436 float answer, remaining_count, count_per_degree;
pairmand 3:8f2b7f4940b5 437 int reading;
pairmand 3:8f2b7f4940b5 438 read_RAM();
pairmand 3:8f2b7f4940b5 439 if (RAM_checksum_error())
pairmand 3:8f2b7f4940b5 440 // Indicate we got a CRC error
pairmand 3:8f2b7f4940b5 441 answer = -1000.0;
pairmand 3:8f2b7f4940b5 442 else {
pairmand 3:8f2b7f4940b5 443 reading = (RAM[1] << 8) + RAM[0];
pairmand 3:8f2b7f4940b5 444 if (reading & 0x8000) { // negative degrees C
pairmand 3:8f2b7f4940b5 445 reading = 0-((reading ^ 0xffff) + 1); // 2's comp then convert to signed int
pairmand 3:8f2b7f4940b5 446 }
pairmand 3:8f2b7f4940b5 447 answer = reading +0.0; // convert to floating point
pairmand 3:8f2b7f4940b5 448 if ( FAMILY_CODE == FAMILY_CODE_DS18B20 ) {
pairmand 3:8f2b7f4940b5 449 answer = answer / 8.0;
pairmand 3:8f2b7f4940b5 450 }
pairmand 3:8f2b7f4940b5 451 else {
pairmand 3:8f2b7f4940b5 452 remaining_count = RAM[6];
pairmand 3:8f2b7f4940b5 453 count_per_degree = RAM[7];
pairmand 3:8f2b7f4940b5 454 answer = answer - 0.25 + (count_per_degree - remaining_count) / count_per_degree;
pairmand 3:8f2b7f4940b5 455 }
pairmand 3:8f2b7f4940b5 456 if (scale=='C' or scale=='c')
pairmand 3:8f2b7f4940b5 457 answer = answer / 2.0;
pairmand 3:8f2b7f4940b5 458 else
pairmand 3:8f2b7f4940b5 459 // Convert to deg F
pairmand 3:8f2b7f4940b5 460 answer = answer * 9.0 / 10.0 + 32.0;
pairmand 3:8f2b7f4940b5 461 }
pairmand 3:8f2b7f4940b5 462 return answer;
pairmand 3:8f2b7f4940b5 463 }
pairmand 3:8f2b7f4940b5 464
pairmand 3:8f2b7f4940b5 465 bool DS1820::read_power_supply(devices device) {
pairmand 3:8f2b7f4940b5 466 // This will return true if the device (or all devices) are Vcc powered
pairmand 3:8f2b7f4940b5 467 // This will return false if the device (or ANY device) is parasite powered
pairmand 3:8f2b7f4940b5 468 if (device==all_devices)
pairmand 3:8f2b7f4940b5 469 skip_ROM(); // Skip ROM command, will poll for any device using parasite power
pairmand 3:8f2b7f4940b5 470 else
pairmand 3:8f2b7f4940b5 471 match_ROM();
pairmand 3:8f2b7f4940b5 472 onewire_byte_out(0xB4); // Read power supply command
pairmand 3:8f2b7f4940b5 473 return onewire_bit_in();
pairmand 3:8f2b7f4940b5 474 }
pairmand 3:8f2b7f4940b5 475
pairmand 3:8f2b7f4940b5 476