Zoltan Hudak / OneWire

Dallas' 1-Wire bus protocol library

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

OneWire.cpp@9:4af0015b0f47, 2019-01-26 (annotated)

Committer:
hudakz
Date:
Sat Jan 26 21:21:27 2019 +0000
Revision:
9:4af0015b0f47
Parent:
8:87fbdaba5535
Child:
10:c89b9ad6097c
STM related parts optimized.

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 9:4af0015b0f47 5 http://www.pjrc.com/teensy/td_libs_Onehtml
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 9:4af0015b0f47 10 contributors were interested in maintaining One 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 9:4af0015b0f47 38 http://www.pjrc.com/teensy/td_libs_Onehtml
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 9:4af0015b0f47 118 #if defined(TARGET_STM)
hudakz 9:4af0015b0f47 119 #define MODE() mode(OpenDrain)
hudakz 9:4af0015b0f47 120 #define INPUT() (*gpio.reg_set = gpio.mask) // write 1 to open drain
hudakz 9:4af0015b0f47 121 #define OUTPUT() // configured as output in the constructor and stays output forever
hudakz 9:4af0015b0f47 122 #define READ() ((*gpio.reg_in & gpio.mask) ? 1 : 0)
hudakz 9:4af0015b0f47 123 #define WRITE(x) write(x)
hudakz 9:4af0015b0f47 124 #else
hudakz 9:4af0015b0f47 125 #define MODE() mode(PullUp)
hudakz 9:4af0015b0f47 126 #define INPUT() input()
hudakz 9:4af0015b0f47 127 #define OUTPUT() output()
hudakz 9:4af0015b0f47 128 #define READ() read()
hudakz 9:4af0015b0f47 129 #define WRITE(x) write(x)
hudakz 9:4af0015b0f47 130 #endif
hudakz 9:4af0015b0f47 131
hudakz 8:87fbdaba5535 132 /**
hudakz 8:87fbdaba5535 133 * @brief
hudakz 8:87fbdaba5535 134 * @note
hudakz 8:87fbdaba5535 135 * @param
hudakz 8:87fbdaba5535 136 * @retval
hudakz 8:87fbdaba5535 137 */
hudakz 8:87fbdaba5535 138 OneWire::OneWire(PinName pin) :
hudakz 9:4af0015b0f47 139 DigitalInOut(pin)
hudakz 7:acf3f0ee66d2 140 {
hudakz 7:acf3f0ee66d2 141 timer.stop();
hudakz 7:acf3f0ee66d2 142 timer.reset();
hudakz 9:4af0015b0f47 143 output(); // configure as output
hudakz 9:4af0015b0f47 144 MODE(); // set mode PullUp/OpenDrain
hudakz 0:acf75feb0947 145 #if ONEWIRE_SEARCH
hudakz 0:acf75feb0947 146 reset_search();
hudakz 0:acf75feb0947 147 #endif
hudakz 0:acf75feb0947 148 }
hudakz 0:acf75feb0947 149
hudakz 0:acf75feb0947 150 // Perform the onewire reset function. We will wait up to 250uS for
hudakz 0:acf75feb0947 151 // the bus to come high, if it doesn't then it is broken or shorted
hudakz 0:acf75feb0947 152 // and we return a 0;
hudakz 0:acf75feb0947 153 //
hudakz 0:acf75feb0947 154 // Returns 1 if a device asserted a presence pulse, 0 otherwise.
hudakz 8:87fbdaba5535 155
hudakz 0:acf75feb0947 156 //
hudakz 0:acf75feb0947 157 uint8_t OneWire::reset(void)
hudakz 0:acf75feb0947 158 {
hudakz 8:87fbdaba5535 159 uint8_t r;
hudakz 8:87fbdaba5535 160 uint8_t retries = 125;
hudakz 0:acf75feb0947 161
hudakz 9:4af0015b0f47 162 INPUT();
hudakz 0:acf75feb0947 163 // wait until the wire is high... just in case
hudakz 0:acf75feb0947 164 do {
hudakz 9:4af0015b0f47 165 if (--retries == 0)
hudakz 8:87fbdaba5535 166 return 0;
hudakz 0:acf75feb0947 167 wait_us(2);
hudakz 9:4af0015b0f47 168 } while (READ() != 1);
hudakz 0:acf75feb0947 169
hudakz 9:4af0015b0f47 170 OUTPUT();
hudakz 9:4af0015b0f47 171 WRITE(0);
hudakz 0:acf75feb0947 172 wait_us(480);
hudakz 9:4af0015b0f47 173 INPUT();
hudakz 9:4af0015b0f47 174 wait_us(65);
hudakz 9:4af0015b0f47 175 r = !READ();
hudakz 9:4af0015b0f47 176 wait_us(420);
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 9:4af0015b0f47 187 OUTPUT();
hudakz 0:acf75feb0947 188 if (v & 1) {
hudakz 9:4af0015b0f47 189 WRITE(0); // drive output low
hudakz 9:4af0015b0f47 190 wait_us(1);
hudakz 9:4af0015b0f47 191 WRITE(1); // drive output high
hudakz 9:4af0015b0f47 192 wait_us(60);
hudakz 8:87fbdaba5535 193 }
hudakz 8:87fbdaba5535 194 else {
hudakz 9:4af0015b0f47 195 WRITE(0); // drive output low
hudakz 9:4af0015b0f47 196 wait_us(60);
hudakz 9:4af0015b0f47 197 WRITE(1); // drive output high
hudakz 9:4af0015b0f47 198 wait_us(1);
hudakz 0:acf75feb0947 199 }
hudakz 0:acf75feb0947 200 }
hudakz 0:acf75feb0947 201
hudakz 0:acf75feb0947 202 //
hudakz 0:acf75feb0947 203 // Read a bit. Port and bit is used to cut lookup time and provide
hudakz 0:acf75feb0947 204 // more certain timing.
hudakz 8:87fbdaba5535 205
hudakz 0:acf75feb0947 206 //
hudakz 0:acf75feb0947 207 uint8_t OneWire::read_bit(void)
hudakz 0:acf75feb0947 208 {
hudakz 0:acf75feb0947 209 uint8_t r;
hudakz 7:acf3f0ee66d2 210 int t;
hudakz 0:acf75feb0947 211
hudakz 9:4af0015b0f47 212 OUTPUT();
hudakz 9:4af0015b0f47 213 WRITE(0);
hudakz 6:d6e084297fb9 214 timer.start();
hudakz 9:4af0015b0f47 215 INPUT();
hudakz 7:acf3f0ee66d2 216 t = timer.read_us();
hudakz 8:87fbdaba5535 217 if (t < 7)
hudakz 8:87fbdaba5535 218 wait_us(7 - t);
hudakz 9:4af0015b0f47 219 timer.reset();
hudakz 9:4af0015b0f47 220 r = READ();
hudakz 6:d6e084297fb9 221 timer.stop();
hudakz 6:d6e084297fb9 222 timer.reset();
hudakz 9:4af0015b0f47 223 wait_us(55);
hudakz 0:acf75feb0947 224 return r;
hudakz 0:acf75feb0947 225 }
hudakz 0:acf75feb0947 226
hudakz 0:acf75feb0947 227 //
hudakz 0:acf75feb0947 228 // Write a byte. The writing code uses the active drivers to raise the
hudakz 0:acf75feb0947 229 // pin high, if you need power after the write (e.g. DS18S20 in
hudakz 0:acf75feb0947 230 // parasite power mode) then set 'power' to 1, otherwise the pin will
hudakz 0:acf75feb0947 231 // go tri-state at the end of the write to avoid heating in a short or
hudakz 0:acf75feb0947 232 // other mishap.
hudakz 8:87fbdaba5535 233
hudakz 0:acf75feb0947 234 //
hudakz 9:4af0015b0f47 235 void OneWire::write_byte(uint8_t v, uint8_t power /* = 0 */ )
hudakz 8:87fbdaba5535 236 {
hudakz 0:acf75feb0947 237 uint8_t bitMask;
hudakz 0:acf75feb0947 238
hudakz 9:4af0015b0f47 239 for (bitMask = 0x01; bitMask; bitMask <<= 1)
hudakz 9:4af0015b0f47 240 write_bit((bitMask & v) ? 1 : 0);
hudakz 8:87fbdaba5535 241 if (!power)
hudakz 9:4af0015b0f47 242 INPUT();
hudakz 0:acf75feb0947 243 }
hudakz 0:acf75feb0947 244
hudakz 8:87fbdaba5535 245 /**
hudakz 8:87fbdaba5535 246 * @brief
hudakz 8:87fbdaba5535 247 * @note
hudakz 8:87fbdaba5535 248 * @param
hudakz 8:87fbdaba5535 249 * @retval
hudakz 8:87fbdaba5535 250 */
hudakz 8:87fbdaba5535 251 void OneWire::write_bytes(const uint8_t* buf, uint16_t count, bool power /* = 0 */ )
hudakz 8:87fbdaba5535 252 {
hudakz 8:87fbdaba5535 253 for (uint16_t i = 0; i < count; i++)
hudakz 9:4af0015b0f47 254 write_byte(buf[i]);
hudakz 8:87fbdaba5535 255 if (!power)
hudakz 9:4af0015b0f47 256 INPUT();
hudakz 0:acf75feb0947 257 }
hudakz 0:acf75feb0947 258
hudakz 0:acf75feb0947 259 //
hudakz 0:acf75feb0947 260 // Read a byte
hudakz 8:87fbdaba5535 261
hudakz 0:acf75feb0947 262 //
hudakz 9:4af0015b0f47 263 uint8_t OneWire::read_byte()
hudakz 8:87fbdaba5535 264 {
hudakz 0:acf75feb0947 265 uint8_t bitMask;
hudakz 0:acf75feb0947 266 uint8_t r = 0;
hudakz 0:acf75feb0947 267
hudakz 0:acf75feb0947 268 for (bitMask = 0x01; bitMask; bitMask <<= 1) {
hudakz 9:4af0015b0f47 269 if (read_bit())
hudakz 8:87fbdaba5535 270 r |= bitMask;
hudakz 0:acf75feb0947 271 }
hudakz 8:87fbdaba5535 272
hudakz 0:acf75feb0947 273 return r;
hudakz 0:acf75feb0947 274 }
hudakz 0:acf75feb0947 275
hudakz 8:87fbdaba5535 276 /**
hudakz 8:87fbdaba5535 277 * @brief
hudakz 8:87fbdaba5535 278 * @note
hudakz 8:87fbdaba5535 279 * @param
hudakz 8:87fbdaba5535 280 * @retval
hudakz 8:87fbdaba5535 281 */
hudakz 8:87fbdaba5535 282 void OneWire::read_bytes(uint8_t* buf, uint16_t count)
hudakz 8:87fbdaba5535 283 {
hudakz 8:87fbdaba5535 284 for (uint16_t i = 0; i < count; i++)
hudakz 9:4af0015b0f47 285 buf[i] = read_byte();
hudakz 0:acf75feb0947 286 }
hudakz 0:acf75feb0947 287
hudakz 0:acf75feb0947 288 //
hudakz 0:acf75feb0947 289 // Do a ROM select
hudakz 8:87fbdaba5535 290
hudakz 0:acf75feb0947 291 //
hudakz 0:acf75feb0947 292 void OneWire::select(const uint8_t rom[8])
hudakz 0:acf75feb0947 293 {
hudakz 0:acf75feb0947 294 uint8_t i;
hudakz 0:acf75feb0947 295
hudakz 9:4af0015b0f47 296 write_byte(0x55); // Choose ROM
hudakz 8:87fbdaba5535 297 for (i = 0; i < 8; i++)
hudakz 9:4af0015b0f47 298 write_byte(rom[i]);
hudakz 0:acf75feb0947 299 }
hudakz 0:acf75feb0947 300
hudakz 0:acf75feb0947 301 //
hudakz 0:acf75feb0947 302 // Do a ROM skip
hudakz 8:87fbdaba5535 303
hudakz 0:acf75feb0947 304 //
hudakz 0:acf75feb0947 305 void OneWire::skip()
hudakz 0:acf75feb0947 306 {
hudakz 9:4af0015b0f47 307 write_byte(0xCC); // Skip ROM
hudakz 0:acf75feb0947 308 }
hudakz 0:acf75feb0947 309
hudakz 8:87fbdaba5535 310 /**
hudakz 8:87fbdaba5535 311 * @brief
hudakz 8:87fbdaba5535 312 * @note
hudakz 8:87fbdaba5535 313 * @param
hudakz 8:87fbdaba5535 314 * @retval
hudakz 8:87fbdaba5535 315 */
hudakz 0:acf75feb0947 316 void OneWire::depower()
hudakz 0:acf75feb0947 317 {
hudakz 9:4af0015b0f47 318 INPUT();
hudakz 0:acf75feb0947 319 }
hudakz 0:acf75feb0947 320
hudakz 0:acf75feb0947 321 #if ONEWIRE_SEARCH
hudakz 8:87fbdaba5535 322 //
hudakz 0:acf75feb0947 323
hudakz 0:acf75feb0947 324 // You need to use this function to start a search again from the beginning.
hudakz 0:acf75feb0947 325 // You do not need to do it for the first search, though you could.
hudakz 8:87fbdaba5535 326
hudakz 0:acf75feb0947 327 //
hudakz 0:acf75feb0947 328 void OneWire::reset_search()
hudakz 0:acf75feb0947 329 {
hudakz 8:87fbdaba5535 330 // reset the search state
hudakz 8:87fbdaba5535 331 LastDiscrepancy = 0;
hudakz 8:87fbdaba5535 332 LastDeviceFlag = false;
hudakz 8:87fbdaba5535 333 LastFamilyDiscrepancy = 0;
hudakz 8:87fbdaba5535 334 for (int i = 7;; i--) {
hudakz 8:87fbdaba5535 335 ROM_NO[i] = 0;
hudakz 8:87fbdaba5535 336 if (i == 0)
hudakz 8:87fbdaba5535 337 break;
hudakz 8:87fbdaba5535 338 }
hudakz 0:acf75feb0947 339 }
hudakz 0:acf75feb0947 340
hudakz 0:acf75feb0947 341 // Setup the search to find the device type 'family_code' on the next call
hudakz 0:acf75feb0947 342 // to search(*newAddr) if it is present.
hudakz 8:87fbdaba5535 343
hudakz 0:acf75feb0947 344 //
hudakz 0:acf75feb0947 345 void OneWire::target_search(uint8_t family_code)
hudakz 0:acf75feb0947 346 {
hudakz 8:87fbdaba5535 347 // set the search state to find SearchFamily type devices
hudakz 8:87fbdaba5535 348 ROM_NO[0] = family_code;
hudakz 8:87fbdaba5535 349 for (uint8_t i = 1; i < 8; i++)
hudakz 8:87fbdaba5535 350 ROM_NO[i] = 0;
hudakz 8:87fbdaba5535 351 LastDiscrepancy = 64;
hudakz 8:87fbdaba5535 352 LastFamilyDiscrepancy = 0;
hudakz 8:87fbdaba5535 353 LastDeviceFlag = false;
hudakz 0:acf75feb0947 354 }
hudakz 0:acf75feb0947 355
hudakz 0:acf75feb0947 356 //
hudakz 0:acf75feb0947 357 // Perform a search. If this function returns a '1' then it has
hudakz 0:acf75feb0947 358 // enumerated the next device and you may retrieve the ROM from the
hudakz 0:acf75feb0947 359 // OneWire::address variable. If there are no devices, no further
hudakz 0:acf75feb0947 360 // devices, or something horrible happens in the middle of the
hudakz 0:acf75feb0947 361 // enumeration then a 0 is returned. If a new device is found then
hudakz 0:acf75feb0947 362 // its address is copied to newAddr. Use OneWire::reset_search() to
hudakz 0:acf75feb0947 363 // start over.
hudakz 0:acf75feb0947 364 //
hudakz 0:acf75feb0947 365 // --- Replaced by the one from the Dallas Semiconductor web site ---
hudakz 0:acf75feb0947 366 //--------------------------------------------------------------------------
hudakz 0:acf75feb0947 367 // Perform the 1-Wire Search Algorithm on the 1-Wire bus using the existing
hudakz 0:acf75feb0947 368 // search state.
hudakz 0:acf75feb0947 369 // Return true : device found, ROM number in ROM_NO buffer
hudakz 0:acf75feb0947 370 // false : device not found, end of search
hudakz 8:87fbdaba5535 371
hudakz 0:acf75feb0947 372 //
hudakz 8:87fbdaba5535 373 uint8_t OneWire::search(uint8_t* newAddr)
hudakz 0:acf75feb0947 374 {
hudakz 8:87fbdaba5535 375 uint8_t id_bit_number;
hudakz 8:87fbdaba5535 376 uint8_t last_zero, rom_byte_number, search_result;
hudakz 8:87fbdaba5535 377 uint8_t id_bit, cmp_id_bit;
hudakz 0:acf75feb0947 378
hudakz 8:87fbdaba5535 379 unsigned char rom_byte_mask, search_direction;
hudakz 0:acf75feb0947 380
hudakz 8:87fbdaba5535 381 // initialize for search
hudakz 8:87fbdaba5535 382 id_bit_number = 1;
hudakz 8:87fbdaba5535 383 last_zero = 0;
hudakz 8:87fbdaba5535 384 rom_byte_number = 0;
hudakz 8:87fbdaba5535 385 rom_byte_mask = 1;
hudakz 8:87fbdaba5535 386 search_result = 0;
hudakz 0:acf75feb0947 387
hudakz 8:87fbdaba5535 388 // if the last call was not the last one
hudakz 8:87fbdaba5535 389 if (!LastDeviceFlag) {
hudakz 8:87fbdaba5535 390 // 1-Wire reset
hudakz 8:87fbdaba5535 391 if (!reset()) {
hudakz 8:87fbdaba5535 392 // reset the search
hudakz 8:87fbdaba5535 393 LastDiscrepancy = 0;
hudakz 8:87fbdaba5535 394 LastDeviceFlag = false;
hudakz 8:87fbdaba5535 395 LastFamilyDiscrepancy = 0;
hudakz 8:87fbdaba5535 396 return false;
hudakz 8:87fbdaba5535 397 }
hudakz 0:acf75feb0947 398
hudakz 8:87fbdaba5535 399 // issue the search command
hudakz 9:4af0015b0f47 400 write_byte(0xF0);
hudakz 0:acf75feb0947 401
hudakz 8:87fbdaba5535 402 // loop to do the search
hudakz 8:87fbdaba5535 403 do {
hudakz 8:87fbdaba5535 404 // read a bit and its complement
hudakz 8:87fbdaba5535 405 id_bit = read_bit();
hudakz 8:87fbdaba5535 406 cmp_id_bit = read_bit();
hudakz 0:acf75feb0947 407
hudakz 8:87fbdaba5535 408 // check for no devices on 1-wire
hudakz 8:87fbdaba5535 409 if ((id_bit == 1) && (cmp_id_bit == 1))
hudakz 8:87fbdaba5535 410 break;
hudakz 8:87fbdaba5535 411 else {
hudakz 8:87fbdaba5535 412 // all devices coupled have 0 or 1
hudakz 8:87fbdaba5535 413 if (id_bit != cmp_id_bit)
hudakz 8:87fbdaba5535 414 search_direction = id_bit; // bit write value for search
hudakz 8:87fbdaba5535 415 else {
hudakz 8:87fbdaba5535 416 // if this discrepancy if before the Last Discrepancy
hudakz 8:87fbdaba5535 417 // on a previous next then pick the same as last time
hudakz 8:87fbdaba5535 418 if (id_bit_number < LastDiscrepancy)
hudakz 8:87fbdaba5535 419 search_direction = ((ROM_NO[rom_byte_number] & rom_byte_mask) > 0);
hudakz 8:87fbdaba5535 420 else
hudakz 8:87fbdaba5535 421 // if equal to last pick 1, if not then pick 0
hudakz 8:87fbdaba5535 422 search_direction = (id_bit_number == LastDiscrepancy);
hudakz 0:acf75feb0947 423
hudakz 8:87fbdaba5535 424 // if 0 was picked then record its position in LastZero
hudakz 8:87fbdaba5535 425 if (search_direction == 0) {
hudakz 8:87fbdaba5535 426 last_zero = id_bit_number;
hudakz 0:acf75feb0947 427
hudakz 8:87fbdaba5535 428 // check for Last discrepancy in family
hudakz 8:87fbdaba5535 429 if (last_zero < 9)
hudakz 8:87fbdaba5535 430 LastFamilyDiscrepancy = last_zero;
hudakz 8:87fbdaba5535 431 }
hudakz 8:87fbdaba5535 432 }
hudakz 0:acf75feb0947 433
hudakz 8:87fbdaba5535 434 // set or clear the bit in the ROM byte rom_byte_number
hudakz 8:87fbdaba5535 435 // with mask rom_byte_mask
hudakz 8:87fbdaba5535 436 if (search_direction == 1)
hudakz 8:87fbdaba5535 437 ROM_NO[rom_byte_number] |= rom_byte_mask;
hudakz 8:87fbdaba5535 438 else
hudakz 8:87fbdaba5535 439 ROM_NO[rom_byte_number] &= ~rom_byte_mask;
hudakz 0:acf75feb0947 440
hudakz 8:87fbdaba5535 441 // serial number search direction write bit
hudakz 8:87fbdaba5535 442 write_bit(search_direction);
hudakz 0:acf75feb0947 443
hudakz 8:87fbdaba5535 444 // increment the byte counter id_bit_number
hudakz 8:87fbdaba5535 445 // and shift the mask rom_byte_mask
hudakz 8:87fbdaba5535 446 id_bit_number++;
hudakz 8:87fbdaba5535 447 rom_byte_mask <<= 1;
hudakz 0:acf75feb0947 448
hudakz 8:87fbdaba5535 449 // if the mask is 0 then go to new SerialNum byte rom_byte_number and reset mask
hudakz 8:87fbdaba5535 450 if (rom_byte_mask == 0) {
hudakz 8:87fbdaba5535 451 rom_byte_number++;
hudakz 8:87fbdaba5535 452 rom_byte_mask = 1;
hudakz 8:87fbdaba5535 453 }
hudakz 0:acf75feb0947 454 }
hudakz 8:87fbdaba5535 455 } while (rom_byte_number < 8);
hudakz 8:87fbdaba5535 456 // loop until through all ROM bytes 0-7
hudakz 8:87fbdaba5535 457 // if the search was successful then
hudakz 8:87fbdaba5535 458 if (!(id_bit_number < 65)) {
hudakz 8:87fbdaba5535 459 // search successful so set LastDiscrepancy,LastDeviceFlag,search_result
hudakz 8:87fbdaba5535 460 LastDiscrepancy = last_zero;
hudakz 0:acf75feb0947 461
hudakz 8:87fbdaba5535 462 // check for last device
hudakz 8:87fbdaba5535 463 if (LastDiscrepancy == 0)
hudakz 8:87fbdaba5535 464 LastDeviceFlag = true;
hudakz 0:acf75feb0947 465
hudakz 8:87fbdaba5535 466 search_result = true;
hudakz 8:87fbdaba5535 467 }
hudakz 8:87fbdaba5535 468 }
hudakz 0:acf75feb0947 469
hudakz 8:87fbdaba5535 470 // if no device found then reset counters so next 'search' will be like a first
hudakz 8:87fbdaba5535 471 if (!search_result || !ROM_NO[0]) {
hudakz 8:87fbdaba5535 472 LastDiscrepancy = 0;
hudakz 8:87fbdaba5535 473 LastDeviceFlag = false;
hudakz 8:87fbdaba5535 474 LastFamilyDiscrepancy = 0;
hudakz 8:87fbdaba5535 475 search_result = false;
hudakz 8:87fbdaba5535 476 }
hudakz 0:acf75feb0947 477
hudakz 8:87fbdaba5535 478 for (int i = 0; i < 8; i++)
hudakz 8:87fbdaba5535 479 newAddr[i] = ROM_NO[i];
hudakz 8:87fbdaba5535 480 return search_result;
hudakz 8:87fbdaba5535 481 }
hudakz 0:acf75feb0947 482 #endif
hudakz 0:acf75feb0947 483 #if ONEWIRE_CRC
hudakz 0:acf75feb0947 484 // The 1-Wire CRC scheme is described in Maxim Application Note 27:
hudakz 8:87fbdaba5535 485
hudakz 0:acf75feb0947 486 // "Understanding and Using Cyclic Redundancy Checks with Maxim iButton Products"
hudakz 0:acf75feb0947 487 // Compute a Dallas Semiconductor 8 bit CRC directly.
hudakz 8:87fbdaba5535 488
hudakz 0:acf75feb0947 489 //
hudakz 8:87fbdaba5535 490 uint8_t OneWire::crc8(const uint8_t* addr, uint8_t len)
hudakz 0:acf75feb0947 491 {
hudakz 0:acf75feb0947 492 uint8_t crc = 0;
hudakz 8:87fbdaba5535 493
hudakz 0:acf75feb0947 494 while (len--) {
hudakz 0:acf75feb0947 495 uint8_t inbyte = *addr++;
hudakz 0:acf75feb0947 496 for (uint8_t i = 8; i; i--) {
hudakz 0:acf75feb0947 497 uint8_t mix = (crc ^ inbyte) & 0x01;
hudakz 0:acf75feb0947 498 crc >>= 1;
hudakz 8:87fbdaba5535 499 if (mix)
hudakz 8:87fbdaba5535 500 crc ^= 0x8C;
hudakz 0:acf75feb0947 501 inbyte >>= 1;
hudakz 0:acf75feb0947 502 }
hudakz 0:acf75feb0947 503 }
hudakz 8:87fbdaba5535 504
hudakz 0:acf75feb0947 505 return crc;
hudakz 0:acf75feb0947 506 }
hudakz 0:acf75feb0947 507 #endif
hudakz 9:4af0015b0f47 508
hudakz 9:4af0015b0f47 509
hudakz 9:4af0015b0f47 510