Zoltan Hudak / OneWire

Dallas' 1-Wire bus protocol library

Dependents:   DS1825 DISCO-F746-Dessiccateur-V1 watersenor_and_temp_code DS1820 ... more

OneWire.cpp@8:87fbdaba5535, 2019-01-21 (annotated)

Committer:
hudakz
Date:
Mon Jan 21 11:37:43 2019 +0000
Revision:
8:87fbdaba5535
Parent:
7:acf3f0ee66d2
Child:
9:4af0015b0f47
Improved for STM boards.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
hudakz 0:acf75feb0947 1 /*
hudakz 0:acf75feb0947 2 Copyright (c) 2007, Jim Studt (original old version - many contributors since)
hudakz 0:acf75feb0947 3
hudakz 0:acf75feb0947 4 The latest version of this library may be found at:
hudakz 0:acf75feb0947 5 http://www.pjrc.com/teensy/td_libs_OneWire.html
hudakz 0:acf75feb0947 6
hudakz 0:acf75feb0947 7 OneWire has been maintained by Paul Stoffregen (paul@pjrc.com) since
hudakz 0:acf75feb0947 8 January 2010. At the time, it was in need of many bug fixes, but had
hudakz 0:acf75feb0947 9 been abandoned the original author (Jim Studt). None of the known
hudakz 0:acf75feb0947 10 contributors were interested in maintaining OneWire. Paul typically
hudakz 0:acf75feb0947 11 works on OneWire every 6 to 12 months. Patches usually wait that
hudakz 0:acf75feb0947 12 long. If anyone is interested in more actively maintaining OneWire,
hudakz 0:acf75feb0947 13 please contact Paul.
hudakz 0:acf75feb0947 14
hudakz 0:acf75feb0947 15 Version 2.2:
hudakz 0:acf75feb0947 16 Teensy 3.0 compatibility, Paul Stoffregen, paul@pjrc.com
hudakz 0:acf75feb0947 17 Arduino Due compatibility, http://arduino.cc/forum/index.php?topic=141030
hudakz 0:acf75feb0947 18 Fix DS18B20 example negative temperature
hudakz 0:acf75feb0947 19 Fix DS18B20 example's low res modes, Ken Butcher
hudakz 0:acf75feb0947 20 Improve reset timing, Mark Tillotson
hudakz 0:acf75feb0947 21 Add const qualifiers, Bertrik Sikken
hudakz 0:acf75feb0947 22 Add initial value input to crc16, Bertrik Sikken
hudakz 0:acf75feb0947 23 Add target_search() function, Scott Roberts
hudakz 0:acf75feb0947 24
hudakz 0:acf75feb0947 25 Version 2.1:
hudakz 0:acf75feb0947 26 Arduino 1.0 compatibility, Paul Stoffregen
hudakz 0:acf75feb0947 27 Improve temperature example, Paul Stoffregen
hudakz 0:acf75feb0947 28 DS250x_PROM example, Guillermo Lovato
hudakz 0:acf75feb0947 29 PIC32 (chipKit) compatibility, Jason Dangel, dangel.jason AT gmail.com
hudakz 0:acf75feb0947 30 Improvements from Glenn Trewitt:
hudakz 0:acf75feb0947 31 - crc16() now works
hudakz 0:acf75feb0947 32 - check_crc16() does all of calculation/checking work.
hudakz 0:acf75feb0947 33 - Added read_bytes() and write_bytes(), to reduce tedious loops.
hudakz 0:acf75feb0947 34 - Added ds2408 example.
hudakz 0:acf75feb0947 35 Delete very old, out-of-date readme file (info is here)
hudakz 0:acf75feb0947 36
hudakz 0:acf75feb0947 37 Version 2.0: Modifications by Paul Stoffregen, January 2010:
hudakz 0:acf75feb0947 38 http://www.pjrc.com/teensy/td_libs_OneWire.html
hudakz 0:acf75feb0947 39 Search fix from Robin James
hudakz 0:acf75feb0947 40 http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1238032295/27#27
hudakz 0:acf75feb0947 41 Use direct optimized I/O in all cases
hudakz 0:acf75feb0947 42 Disable interrupts during timing critical sections
hudakz 0:acf75feb0947 43 (this solves many random communication errors)
hudakz 0:acf75feb0947 44 Disable interrupts during read-modify-write I/O
hudakz 0:acf75feb0947 45 Reduce RAM consumption by eliminating unnecessary
hudakz 0:acf75feb0947 46 variables and trimming many to 8 bits
hudakz 0:acf75feb0947 47 Optimize both crc8 - table version moved to flash
hudakz 0:acf75feb0947 48
hudakz 0:acf75feb0947 49 Modified to work with larger numbers of devices - avoids loop.
hudakz 0:acf75feb0947 50 Tested in Arduino 11 alpha with 12 sensors.
hudakz 0:acf75feb0947 51 26 Sept 2008 -- Robin James
hudakz 0:acf75feb0947 52 http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1238032295/27#27
hudakz 0:acf75feb0947 53
hudakz 0:acf75feb0947 54 Updated to work with arduino-0008 and to include skip() as of
hudakz 0:acf75feb0947 55 2007/07/06. --RJL20
hudakz 0:acf75feb0947 56
hudakz 0:acf75feb0947 57 Modified to calculate the 8-bit CRC directly, avoiding the need for
hudakz 0:acf75feb0947 58 the 256-byte lookup table to be loaded in RAM. Tested in arduino-0010
hudakz 0:acf75feb0947 59 -- Tom Pollard, Jan 23, 2008
hudakz 0:acf75feb0947 60
hudakz 0:acf75feb0947 61 Jim Studt's original library was modified by Josh Larios.
hudakz 0:acf75feb0947 62
hudakz 0:acf75feb0947 63 Tom Pollard, pollard@alum.mit.edu, contributed around May 20, 2008
hudakz 0:acf75feb0947 64
hudakz 0:acf75feb0947 65 Permission is hereby granted, free of charge, to any person obtaining
hudakz 0:acf75feb0947 66 a copy of this software and associated documentation files (the
hudakz 0:acf75feb0947 67 "Software"), to deal in the Software without restriction, including
hudakz 0:acf75feb0947 68 without limitation the rights to use, copy, modify, merge, publish,
hudakz 0:acf75feb0947 69 distribute, sublicense, and/or sell copies of the Software, and to
hudakz 0:acf75feb0947 70 permit persons to whom the Software is furnished to do so, subject to
hudakz 0:acf75feb0947 71 the following conditions:
hudakz 0:acf75feb0947 72
hudakz 0:acf75feb0947 73 The above copyright notice and this permission notice shall be
hudakz 0:acf75feb0947 74 included in all copies or substantial portions of the Software.
hudakz 0:acf75feb0947 75
hudakz 0:acf75feb0947 76 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
hudakz 0:acf75feb0947 77 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
hudakz 0:acf75feb0947 78 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
hudakz 0:acf75feb0947 79 NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
hudakz 0:acf75feb0947 80 LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
hudakz 0:acf75feb0947 81 OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
hudakz 0:acf75feb0947 82 WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
hudakz 0:acf75feb0947 83
hudakz 0:acf75feb0947 84 Much of the code was inspired by Derek Yerger's code, though I don't
hudakz 0:acf75feb0947 85 think much of that remains. In any event that was..
hudakz 0:acf75feb0947 86 (copyleft) 2006 by Derek Yerger - Free to distribute freely.
hudakz 0:acf75feb0947 87
hudakz 0:acf75feb0947 88 The CRC code was excerpted and inspired by the Dallas Semiconductor
hudakz 0:acf75feb0947 89 sample code bearing this copyright.
hudakz 0:acf75feb0947 90 //---------------------------------------------------------------------------
hudakz 0:acf75feb0947 91 // Copyright (C) 2000 Dallas Semiconductor Corporation, All Rights Reserved.
hudakz 0:acf75feb0947 92 //
hudakz 0:acf75feb0947 93 // Permission is hereby granted, free of charge, to any person obtaining a
hudakz 0:acf75feb0947 94 // copy of this software and associated documentation files (the "Software"),
hudakz 0:acf75feb0947 95 // to deal in the Software without restriction, including without limitation
hudakz 0:acf75feb0947 96 // the rights to use, copy, modify, merge, publish, distribute, sublicense,
hudakz 0:acf75feb0947 97 // and/or sell copies of the Software, and to permit persons to whom the
hudakz 0:acf75feb0947 98 // Software is furnished to do so, subject to the following conditions:
hudakz 0:acf75feb0947 99 //
hudakz 0:acf75feb0947 100 // The above copyright notice and this permission notice shall be included
hudakz 0:acf75feb0947 101 // in all copies or substantial portions of the Software.
hudakz 0:acf75feb0947 102 //
hudakz 0:acf75feb0947 103 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
hudakz 0:acf75feb0947 104 // OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
hudakz 0:acf75feb0947 105 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
hudakz 0:acf75feb0947 106 // IN NO EVENT SHALL DALLAS SEMICONDUCTOR BE LIABLE FOR ANY CLAIM, DAMAGES
hudakz 0:acf75feb0947 107 // OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
hudakz 0:acf75feb0947 108 // ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
hudakz 0:acf75feb0947 109 // OTHER DEALINGS IN THE SOFTWARE.
hudakz 0:acf75feb0947 110 //
hudakz 0:acf75feb0947 111 // Except as contained in this notice, the name of Dallas Semiconductor
hudakz 0:acf75feb0947 112 // shall not be used except as stated in the Dallas Semiconductor
hudakz 0:acf75feb0947 113 // Branding Policy.
hudakz 0:acf75feb0947 114 //--------------------------------------------------------------------------
hudakz 0:acf75feb0947 115 */
hudakz 0:acf75feb0947 116 #include "OneWire.h"
hudakz 0:acf75feb0947 117
hudakz 8:87fbdaba5535 118 /**
hudakz 8:87fbdaba5535 119 * @brief
hudakz 8:87fbdaba5535 120 * @note
hudakz 8:87fbdaba5535 121 * @param
hudakz 8:87fbdaba5535 122 * @retval
hudakz 8:87fbdaba5535 123 */
hudakz 8:87fbdaba5535 124 OneWire::OneWire(PinName pin) :
hudakz 0:acf75feb0947 125 wire(pin)
hudakz 7:acf3f0ee66d2 126 {
hudakz 7:acf3f0ee66d2 127 timer.stop();
hudakz 7:acf3f0ee66d2 128 timer.reset();
hudakz 8:87fbdaba5535 129 #if defined(TARGET_STM)
hudakz 8:87fbdaba5535 130 wire.mode(OpenDrain);
hudakz 8:87fbdaba5535 131 #else
hudakz 8:87fbdaba5535 132 wire.mode(PullUp);
hudakz 8:87fbdaba5535 133 #endif
hudakz 0:acf75feb0947 134 #if ONEWIRE_SEARCH
hudakz 0:acf75feb0947 135 reset_search();
hudakz 0:acf75feb0947 136 #endif
hudakz 0:acf75feb0947 137 }
hudakz 0:acf75feb0947 138
hudakz 0:acf75feb0947 139 // Perform the onewire reset function. We will wait up to 250uS for
hudakz 0:acf75feb0947 140 // the bus to come high, if it doesn't then it is broken or shorted
hudakz 0:acf75feb0947 141 // and we return a 0;
hudakz 0:acf75feb0947 142 //
hudakz 0:acf75feb0947 143 // Returns 1 if a device asserted a presence pulse, 0 otherwise.
hudakz 8:87fbdaba5535 144
hudakz 0:acf75feb0947 145 //
hudakz 0:acf75feb0947 146 uint8_t OneWire::reset(void)
hudakz 0:acf75feb0947 147 {
hudakz 8:87fbdaba5535 148 uint8_t r;
hudakz 8:87fbdaba5535 149 uint8_t retries = 125;
hudakz 0:acf75feb0947 150
hudakz 8:87fbdaba5535 151 #if defined(TARGET_STM)
hudakz 8:87fbdaba5535 152 wire = 1;
hudakz 8:87fbdaba5535 153 #else
hudakz 0:acf75feb0947 154 wire.input();
hudakz 8:87fbdaba5535 155 #endif
hudakz 0:acf75feb0947 156 // wait until the wire is high... just in case
hudakz 8:87fbdaba5535 157
hudakz 0:acf75feb0947 158 do {
hudakz 0:acf75feb0947 159 if (--retries == 0) {
hudakz 8:87fbdaba5535 160 return 0;
hudakz 0:acf75feb0947 161 }
hudakz 8:87fbdaba5535 162
hudakz 0:acf75feb0947 163 wait_us(2);
hudakz 0:acf75feb0947 164 } while (wire.read() != 1);
hudakz 0:acf75feb0947 165
hudakz 0:acf75feb0947 166 wire.output();
hudakz 0:acf75feb0947 167 wire = 0;
hudakz 0:acf75feb0947 168 wait_us(480);
hudakz 8:87fbdaba5535 169 #if defined(TARGET_STM)
hudakz 8:87fbdaba5535 170 wire = 1;
hudakz 8:87fbdaba5535 171 #else
hudakz 0:acf75feb0947 172 wire.input();
hudakz 8:87fbdaba5535 173 #endif
hudakz 0:acf75feb0947 174 wait_us(70);
hudakz 0:acf75feb0947 175 r = !wire.read();
hudakz 0:acf75feb0947 176 wait_us(410);
hudakz 0:acf75feb0947 177 return r;
hudakz 0:acf75feb0947 178 }
hudakz 0:acf75feb0947 179
hudakz 0:acf75feb0947 180 //
hudakz 0:acf75feb0947 181 // Write a bit. Port and bit is used to cut lookup time and provide
hudakz 0:acf75feb0947 182 // more certain timing.
hudakz 8:87fbdaba5535 183
hudakz 0:acf75feb0947 184 //
hudakz 0:acf75feb0947 185 void OneWire::write_bit(uint8_t v)
hudakz 0:acf75feb0947 186 {
hudakz 8:87fbdaba5535 187 #if !defined(TARGET_STM)
hudakz 0:acf75feb0947 188 wire.output();
hudakz 8:87fbdaba5535 189 #endif
hudakz 0:acf75feb0947 190 if (v & 1) {
hudakz 0:acf75feb0947 191 wire = 0; // drive output low
hudakz 0:acf75feb0947 192 wait_us(10);
hudakz 0:acf75feb0947 193 wire = 1; // drive output high
hudakz 0:acf75feb0947 194 wait_us(55);
hudakz 8:87fbdaba5535 195 }
hudakz 8:87fbdaba5535 196 else {
hudakz 0:acf75feb0947 197 wire = 0; // drive output low
hudakz 0:acf75feb0947 198 wait_us(65);
hudakz 0:acf75feb0947 199 wire = 1; // drive output high
hudakz 0:acf75feb0947 200 wait_us(5);
hudakz 0:acf75feb0947 201 }
hudakz 0:acf75feb0947 202 }
hudakz 0:acf75feb0947 203
hudakz 0:acf75feb0947 204 //
hudakz 0:acf75feb0947 205 // Read a bit. Port and bit is used to cut lookup time and provide
hudakz 0:acf75feb0947 206 // more certain timing.
hudakz 8:87fbdaba5535 207
hudakz 0:acf75feb0947 208 //
hudakz 0:acf75feb0947 209 uint8_t OneWire::read_bit(void)
hudakz 0:acf75feb0947 210 {
hudakz 0:acf75feb0947 211 uint8_t r;
hudakz 7:acf3f0ee66d2 212 int t;
hudakz 0:acf75feb0947 213
hudakz 8:87fbdaba5535 214 #if !defined(TARGET_STM)
hudakz 0:acf75feb0947 215 wire.output();
hudakz 8:87fbdaba5535 216 #endif
hudakz 0:acf75feb0947 217 wire = 0;
hudakz 6:d6e084297fb9 218 timer.start();
hudakz 8:87fbdaba5535 219 #if defined(TARGET_STM)
hudakz 8:87fbdaba5535 220 wire = 1;
hudakz 8:87fbdaba5535 221 #else
hudakz 0:acf75feb0947 222 wire.input();
hudakz 8:87fbdaba5535 223 #endif
hudakz 7:acf3f0ee66d2 224 t = timer.read_us();
hudakz 8:87fbdaba5535 225 if (t < 7)
hudakz 8:87fbdaba5535 226 wait_us(7 - t);
hudakz 0:acf75feb0947 227 r = wire.read();
hudakz 6:d6e084297fb9 228 timer.stop();
hudakz 6:d6e084297fb9 229 timer.reset();
hudakz 0:acf75feb0947 230 wait_us(54);
hudakz 0:acf75feb0947 231 return r;
hudakz 0:acf75feb0947 232 }
hudakz 0:acf75feb0947 233
hudakz 0:acf75feb0947 234 //
hudakz 0:acf75feb0947 235 // Write a byte. The writing code uses the active drivers to raise the
hudakz 0:acf75feb0947 236 // pin high, if you need power after the write (e.g. DS18S20 in
hudakz 0:acf75feb0947 237 // parasite power mode) then set 'power' to 1, otherwise the pin will
hudakz 0:acf75feb0947 238 // go tri-state at the end of the write to avoid heating in a short or
hudakz 0:acf75feb0947 239 // other mishap.
hudakz 8:87fbdaba5535 240
hudakz 0:acf75feb0947 241 //
hudakz 8:87fbdaba5535 242 void OneWire::write(uint8_t v, uint8_t power /* = 0 */ )
hudakz 8:87fbdaba5535 243 {
hudakz 0:acf75feb0947 244 uint8_t bitMask;
hudakz 0:acf75feb0947 245
hudakz 0:acf75feb0947 246 for (bitMask = 0x01; bitMask; bitMask <<= 1) {
hudakz 8:87fbdaba5535 247 OneWire::write_bit((bitMask & v) ? 1 : 0);
hudakz 0:acf75feb0947 248 }
hudakz 8:87fbdaba5535 249
hudakz 8:87fbdaba5535 250 if (!power)
hudakz 8:87fbdaba5535 251 {
hudakz 8:87fbdaba5535 252 #if defined(TARGET_STM)
hudakz 8:87fbdaba5535 253 wire = 1;
hudakz 8:87fbdaba5535 254 #else
hudakz 0:acf75feb0947 255 wire.input();
hudakz 8:87fbdaba5535 256 #endif
hudakz 0:acf75feb0947 257 }
hudakz 0:acf75feb0947 258 }
hudakz 0:acf75feb0947 259
hudakz 8:87fbdaba5535 260 /**
hudakz 8:87fbdaba5535 261 * @brief
hudakz 8:87fbdaba5535 262 * @note
hudakz 8:87fbdaba5535 263 * @param
hudakz 8:87fbdaba5535 264 * @retval
hudakz 8:87fbdaba5535 265 */
hudakz 8:87fbdaba5535 266 void OneWire::write_bytes(const uint8_t* buf, uint16_t count, bool power /* = 0 */ )
hudakz 8:87fbdaba5535 267 {
hudakz 8:87fbdaba5535 268 for (uint16_t i = 0; i < count; i++)
hudakz 8:87fbdaba5535 269 write(buf[i]);
hudakz 8:87fbdaba5535 270 if (!power)
hudakz 8:87fbdaba5535 271 {
hudakz 8:87fbdaba5535 272 #if defined(TARGET_STM)
hudakz 8:87fbdaba5535 273 wire = 1;
hudakz 8:87fbdaba5535 274 #else
hudakz 0:acf75feb0947 275 wire.input();
hudakz 8:87fbdaba5535 276 #endif
hudakz 8:87fbdaba5535 277 }
hudakz 0:acf75feb0947 278 }
hudakz 0:acf75feb0947 279
hudakz 0:acf75feb0947 280 //
hudakz 0:acf75feb0947 281 // Read a byte
hudakz 8:87fbdaba5535 282
hudakz 0:acf75feb0947 283 //
hudakz 8:87fbdaba5535 284 uint8_t OneWire::read()
hudakz 8:87fbdaba5535 285 {
hudakz 0:acf75feb0947 286 uint8_t bitMask;
hudakz 0:acf75feb0947 287 uint8_t r = 0;
hudakz 0:acf75feb0947 288
hudakz 0:acf75feb0947 289 for (bitMask = 0x01; bitMask; bitMask <<= 1) {
hudakz 8:87fbdaba5535 290 if (OneWire::read_bit())
hudakz 8:87fbdaba5535 291 r |= bitMask;
hudakz 0:acf75feb0947 292 }
hudakz 8:87fbdaba5535 293
hudakz 0:acf75feb0947 294 return r;
hudakz 0:acf75feb0947 295 }
hudakz 0:acf75feb0947 296
hudakz 8:87fbdaba5535 297 /**
hudakz 8:87fbdaba5535 298 * @brief
hudakz 8:87fbdaba5535 299 * @note
hudakz 8:87fbdaba5535 300 * @param
hudakz 8:87fbdaba5535 301 * @retval
hudakz 8:87fbdaba5535 302 */
hudakz 8:87fbdaba5535 303 void OneWire::read_bytes(uint8_t* buf, uint16_t count)
hudakz 8:87fbdaba5535 304 {
hudakz 8:87fbdaba5535 305 for (uint16_t i = 0; i < count; i++)
hudakz 8:87fbdaba5535 306 buf[i] = read();
hudakz 0:acf75feb0947 307 }
hudakz 0:acf75feb0947 308
hudakz 0:acf75feb0947 309 //
hudakz 0:acf75feb0947 310 // Do a ROM select
hudakz 8:87fbdaba5535 311
hudakz 0:acf75feb0947 312 //
hudakz 0:acf75feb0947 313 void OneWire::select(const uint8_t rom[8])
hudakz 0:acf75feb0947 314 {
hudakz 0:acf75feb0947 315 uint8_t i;
hudakz 0:acf75feb0947 316
hudakz 8:87fbdaba5535 317 write(0x55); // Choose ROM
hudakz 8:87fbdaba5535 318 for (i = 0; i < 8; i++)
hudakz 8:87fbdaba5535 319 write(rom[i]);
hudakz 0:acf75feb0947 320 }
hudakz 0:acf75feb0947 321
hudakz 0:acf75feb0947 322 //
hudakz 0:acf75feb0947 323 // Do a ROM skip
hudakz 8:87fbdaba5535 324
hudakz 0:acf75feb0947 325 //
hudakz 0:acf75feb0947 326 void OneWire::skip()
hudakz 0:acf75feb0947 327 {
hudakz 8:87fbdaba5535 328 write(0xCC); // Skip ROM
hudakz 0:acf75feb0947 329 }
hudakz 0:acf75feb0947 330
hudakz 8:87fbdaba5535 331 /**
hudakz 8:87fbdaba5535 332 * @brief
hudakz 8:87fbdaba5535 333 * @note
hudakz 8:87fbdaba5535 334 * @param
hudakz 8:87fbdaba5535 335 * @retval
hudakz 8:87fbdaba5535 336 */
hudakz 0:acf75feb0947 337 void OneWire::depower()
hudakz 0:acf75feb0947 338 {
hudakz 8:87fbdaba5535 339 #if defined(TARGET_STM)
hudakz 8:87fbdaba5535 340 wire = 1;
hudakz 8:87fbdaba5535 341 #else
hudakz 0:acf75feb0947 342 wire.input();
hudakz 8:87fbdaba5535 343 #endif
hudakz 0:acf75feb0947 344 }
hudakz 0:acf75feb0947 345
hudakz 0:acf75feb0947 346 #if ONEWIRE_SEARCH
hudakz 8:87fbdaba5535 347 //
hudakz 0:acf75feb0947 348
hudakz 0:acf75feb0947 349 // You need to use this function to start a search again from the beginning.
hudakz 0:acf75feb0947 350 // You do not need to do it for the first search, though you could.
hudakz 8:87fbdaba5535 351
hudakz 0:acf75feb0947 352 //
hudakz 0:acf75feb0947 353 void OneWire::reset_search()
hudakz 0:acf75feb0947 354 {
hudakz 8:87fbdaba5535 355 // reset the search state
hudakz 8:87fbdaba5535 356 LastDiscrepancy = 0;
hudakz 8:87fbdaba5535 357 LastDeviceFlag = false;
hudakz 8:87fbdaba5535 358 LastFamilyDiscrepancy = 0;
hudakz 8:87fbdaba5535 359 for (int i = 7;; i--) {
hudakz 8:87fbdaba5535 360 ROM_NO[i] = 0;
hudakz 8:87fbdaba5535 361 if (i == 0)
hudakz 8:87fbdaba5535 362 break;
hudakz 8:87fbdaba5535 363 }
hudakz 0:acf75feb0947 364 }
hudakz 0:acf75feb0947 365
hudakz 0:acf75feb0947 366 // Setup the search to find the device type 'family_code' on the next call
hudakz 0:acf75feb0947 367 // to search(*newAddr) if it is present.
hudakz 8:87fbdaba5535 368
hudakz 0:acf75feb0947 369 //
hudakz 0:acf75feb0947 370 void OneWire::target_search(uint8_t family_code)
hudakz 0:acf75feb0947 371 {
hudakz 8:87fbdaba5535 372 // set the search state to find SearchFamily type devices
hudakz 8:87fbdaba5535 373 ROM_NO[0] = family_code;
hudakz 8:87fbdaba5535 374 for (uint8_t i = 1; i < 8; i++)
hudakz 8:87fbdaba5535 375 ROM_NO[i] = 0;
hudakz 8:87fbdaba5535 376 LastDiscrepancy = 64;
hudakz 8:87fbdaba5535 377 LastFamilyDiscrepancy = 0;
hudakz 8:87fbdaba5535 378 LastDeviceFlag = false;
hudakz 0:acf75feb0947 379 }
hudakz 0:acf75feb0947 380
hudakz 0:acf75feb0947 381 //
hudakz 0:acf75feb0947 382 // Perform a search. If this function returns a '1' then it has
hudakz 0:acf75feb0947 383 // enumerated the next device and you may retrieve the ROM from the
hudakz 0:acf75feb0947 384 // OneWire::address variable. If there are no devices, no further
hudakz 0:acf75feb0947 385 // devices, or something horrible happens in the middle of the
hudakz 0:acf75feb0947 386 // enumeration then a 0 is returned. If a new device is found then
hudakz 0:acf75feb0947 387 // its address is copied to newAddr. Use OneWire::reset_search() to
hudakz 0:acf75feb0947 388 // start over.
hudakz 0:acf75feb0947 389 //
hudakz 0:acf75feb0947 390 // --- Replaced by the one from the Dallas Semiconductor web site ---
hudakz 0:acf75feb0947 391 //--------------------------------------------------------------------------
hudakz 0:acf75feb0947 392 // Perform the 1-Wire Search Algorithm on the 1-Wire bus using the existing
hudakz 0:acf75feb0947 393 // search state.
hudakz 0:acf75feb0947 394 // Return true : device found, ROM number in ROM_NO buffer
hudakz 0:acf75feb0947 395 // false : device not found, end of search
hudakz 8:87fbdaba5535 396
hudakz 0:acf75feb0947 397 //
hudakz 8:87fbdaba5535 398 uint8_t OneWire::search(uint8_t* newAddr)
hudakz 0:acf75feb0947 399 {
hudakz 8:87fbdaba5535 400 uint8_t id_bit_number;
hudakz 8:87fbdaba5535 401 uint8_t last_zero, rom_byte_number, search_result;
hudakz 8:87fbdaba5535 402 uint8_t id_bit, cmp_id_bit;
hudakz 0:acf75feb0947 403
hudakz 8:87fbdaba5535 404 unsigned char rom_byte_mask, search_direction;
hudakz 0:acf75feb0947 405
hudakz 8:87fbdaba5535 406 // initialize for search
hudakz 8:87fbdaba5535 407 id_bit_number = 1;
hudakz 8:87fbdaba5535 408 last_zero = 0;
hudakz 8:87fbdaba5535 409 rom_byte_number = 0;
hudakz 8:87fbdaba5535 410 rom_byte_mask = 1;
hudakz 8:87fbdaba5535 411 search_result = 0;
hudakz 0:acf75feb0947 412
hudakz 8:87fbdaba5535 413 // if the last call was not the last one
hudakz 8:87fbdaba5535 414 if (!LastDeviceFlag) {
hudakz 8:87fbdaba5535 415 // 1-Wire reset
hudakz 8:87fbdaba5535 416 if (!reset()) {
hudakz 8:87fbdaba5535 417 // reset the search
hudakz 8:87fbdaba5535 418 LastDiscrepancy = 0;
hudakz 8:87fbdaba5535 419 LastDeviceFlag = false;
hudakz 8:87fbdaba5535 420 LastFamilyDiscrepancy = 0;
hudakz 8:87fbdaba5535 421 return false;
hudakz 8:87fbdaba5535 422 }
hudakz 0:acf75feb0947 423
hudakz 8:87fbdaba5535 424 // issue the search command
hudakz 8:87fbdaba5535 425 write(0xF0);
hudakz 0:acf75feb0947 426
hudakz 8:87fbdaba5535 427 // loop to do the search
hudakz 8:87fbdaba5535 428 do {
hudakz 8:87fbdaba5535 429 // read a bit and its complement
hudakz 8:87fbdaba5535 430 id_bit = read_bit();
hudakz 8:87fbdaba5535 431 cmp_id_bit = read_bit();
hudakz 0:acf75feb0947 432
hudakz 8:87fbdaba5535 433 // check for no devices on 1-wire
hudakz 8:87fbdaba5535 434 if ((id_bit == 1) && (cmp_id_bit == 1))
hudakz 8:87fbdaba5535 435 break;
hudakz 8:87fbdaba5535 436 else {
hudakz 8:87fbdaba5535 437 // all devices coupled have 0 or 1
hudakz 8:87fbdaba5535 438 if (id_bit != cmp_id_bit)
hudakz 8:87fbdaba5535 439 search_direction = id_bit; // bit write value for search
hudakz 8:87fbdaba5535 440 else {
hudakz 8:87fbdaba5535 441 // if this discrepancy if before the Last Discrepancy
hudakz 8:87fbdaba5535 442 // on a previous next then pick the same as last time
hudakz 8:87fbdaba5535 443 if (id_bit_number < LastDiscrepancy)
hudakz 8:87fbdaba5535 444 search_direction = ((ROM_NO[rom_byte_number] & rom_byte_mask) > 0);
hudakz 8:87fbdaba5535 445 else
hudakz 8:87fbdaba5535 446 // if equal to last pick 1, if not then pick 0
hudakz 8:87fbdaba5535 447 search_direction = (id_bit_number == LastDiscrepancy);
hudakz 0:acf75feb0947 448
hudakz 8:87fbdaba5535 449 // if 0 was picked then record its position in LastZero
hudakz 8:87fbdaba5535 450 if (search_direction == 0) {
hudakz 8:87fbdaba5535 451 last_zero = id_bit_number;
hudakz 0:acf75feb0947 452
hudakz 8:87fbdaba5535 453 // check for Last discrepancy in family
hudakz 8:87fbdaba5535 454 if (last_zero < 9)
hudakz 8:87fbdaba5535 455 LastFamilyDiscrepancy = last_zero;
hudakz 8:87fbdaba5535 456 }
hudakz 8:87fbdaba5535 457 }
hudakz 0:acf75feb0947 458
hudakz 8:87fbdaba5535 459 // set or clear the bit in the ROM byte rom_byte_number
hudakz 8:87fbdaba5535 460 // with mask rom_byte_mask
hudakz 8:87fbdaba5535 461 if (search_direction == 1)
hudakz 8:87fbdaba5535 462 ROM_NO[rom_byte_number] |= rom_byte_mask;
hudakz 8:87fbdaba5535 463 else
hudakz 8:87fbdaba5535 464 ROM_NO[rom_byte_number] &= ~rom_byte_mask;
hudakz 0:acf75feb0947 465
hudakz 8:87fbdaba5535 466 // serial number search direction write bit
hudakz 8:87fbdaba5535 467 write_bit(search_direction);
hudakz 0:acf75feb0947 468
hudakz 8:87fbdaba5535 469 // increment the byte counter id_bit_number
hudakz 8:87fbdaba5535 470 // and shift the mask rom_byte_mask
hudakz 8:87fbdaba5535 471 id_bit_number++;
hudakz 8:87fbdaba5535 472 rom_byte_mask <<= 1;
hudakz 0:acf75feb0947 473
hudakz 8:87fbdaba5535 474 // if the mask is 0 then go to new SerialNum byte rom_byte_number and reset mask
hudakz 8:87fbdaba5535 475 if (rom_byte_mask == 0) {
hudakz 8:87fbdaba5535 476 rom_byte_number++;
hudakz 8:87fbdaba5535 477 rom_byte_mask = 1;
hudakz 8:87fbdaba5535 478 }
hudakz 0:acf75feb0947 479 }
hudakz 8:87fbdaba5535 480 } while (rom_byte_number < 8);
hudakz 8:87fbdaba5535 481 // loop until through all ROM bytes 0-7
hudakz 8:87fbdaba5535 482 // if the search was successful then
hudakz 8:87fbdaba5535 483 if (!(id_bit_number < 65)) {
hudakz 8:87fbdaba5535 484 // search successful so set LastDiscrepancy,LastDeviceFlag,search_result
hudakz 8:87fbdaba5535 485 LastDiscrepancy = last_zero;
hudakz 0:acf75feb0947 486
hudakz 8:87fbdaba5535 487 // check for last device
hudakz 8:87fbdaba5535 488 if (LastDiscrepancy == 0)
hudakz 8:87fbdaba5535 489 LastDeviceFlag = true;
hudakz 0:acf75feb0947 490
hudakz 8:87fbdaba5535 491 search_result = true;
hudakz 8:87fbdaba5535 492 }
hudakz 8:87fbdaba5535 493 }
hudakz 0:acf75feb0947 494
hudakz 8:87fbdaba5535 495 // if no device found then reset counters so next 'search' will be like a first
hudakz 8:87fbdaba5535 496 if (!search_result || !ROM_NO[0]) {
hudakz 8:87fbdaba5535 497 LastDiscrepancy = 0;
hudakz 8:87fbdaba5535 498 LastDeviceFlag = false;
hudakz 8:87fbdaba5535 499 LastFamilyDiscrepancy = 0;
hudakz 8:87fbdaba5535 500 search_result = false;
hudakz 8:87fbdaba5535 501 }
hudakz 0:acf75feb0947 502
hudakz 8:87fbdaba5535 503 for (int i = 0; i < 8; i++)
hudakz 8:87fbdaba5535 504 newAddr[i] = ROM_NO[i];
hudakz 8:87fbdaba5535 505 return search_result;
hudakz 8:87fbdaba5535 506 }
hudakz 0:acf75feb0947 507 #endif
hudakz 0:acf75feb0947 508 #if ONEWIRE_CRC
hudakz 0:acf75feb0947 509 // The 1-Wire CRC scheme is described in Maxim Application Note 27:
hudakz 8:87fbdaba5535 510
hudakz 0:acf75feb0947 511 // "Understanding and Using Cyclic Redundancy Checks with Maxim iButton Products"
hudakz 0:acf75feb0947 512 // Compute a Dallas Semiconductor 8 bit CRC directly.
hudakz 8:87fbdaba5535 513
hudakz 0:acf75feb0947 514 //
hudakz 8:87fbdaba5535 515 uint8_t OneWire::crc8(const uint8_t* addr, uint8_t len)
hudakz 0:acf75feb0947 516 {
hudakz 0:acf75feb0947 517 uint8_t crc = 0;
hudakz 8:87fbdaba5535 518
hudakz 0:acf75feb0947 519 while (len--) {
hudakz 0:acf75feb0947 520 uint8_t inbyte = *addr++;
hudakz 0:acf75feb0947 521 for (uint8_t i = 8; i; i--) {
hudakz 0:acf75feb0947 522 uint8_t mix = (crc ^ inbyte) & 0x01;
hudakz 0:acf75feb0947 523 crc >>= 1;
hudakz 8:87fbdaba5535 524 if (mix)
hudakz 8:87fbdaba5535 525 crc ^= 0x8C;
hudakz 0:acf75feb0947 526 inbyte >>= 1;
hudakz 0:acf75feb0947 527 }
hudakz 0:acf75feb0947 528 }
hudakz 8:87fbdaba5535 529
hudakz 0:acf75feb0947 530 return crc;
hudakz 0:acf75feb0947 531 }
hudakz 0:acf75feb0947 532 #endif