Zoltan Hudak / OneWire

Dallas' 1-Wire bus protocol library

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

OneWire.cpp@10:c89b9ad6097c, 2019-01-27 (annotated)

Committer:
hudakz
Date:
Sun Jan 27 14:11:28 2019 +0000
Revision:
10:c89b9ad6097c
Parent:
9:4af0015b0f47
Child:
11:bc8ed7280966
Modified.

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 8:87fbdaba5535 118 /**
hudakz 10:c89b9ad6097c 119 * @brief Constructs a OneWire object.
hudakz 10:c89b9ad6097c 120 * @note GPIO is configured as output and an internal pull up resistor is connected.
hudakz 10:c89b9ad6097c 121 * But because for STM chips it takes very long time to change from output
hudakz 10:c89b9ad6097c 122 * to input an open drain mode is used rather and the GPIO remains output forever.
hudakz 8:87fbdaba5535 123 * @param
hudakz 8:87fbdaba5535 124 * @retval
hudakz 8:87fbdaba5535 125 */
hudakz 8:87fbdaba5535 126 OneWire::OneWire(PinName pin) :
hudakz 9:4af0015b0f47 127 DigitalInOut(pin)
hudakz 7:acf3f0ee66d2 128 {
hudakz 7:acf3f0ee66d2 129 timer.stop();
hudakz 7:acf3f0ee66d2 130 timer.reset();
hudakz 10:c89b9ad6097c 131 MODE(); // set mode either PullUp or OpenDrain
hudakz 0:acf75feb0947 132 #if ONEWIRE_SEARCH
hudakz 0:acf75feb0947 133 reset_search();
hudakz 0:acf75feb0947 134 #endif
hudakz 0:acf75feb0947 135 }
hudakz 0:acf75feb0947 136
hudakz 10:c89b9ad6097c 137 /**
hudakz 10:c89b9ad6097c 138 * @brief Performs the onewire reset function.
hudakz 10:c89b9ad6097c 139 * @note We will wait up to 250uS for the bus to come high,
hudakz 10:c89b9ad6097c 140 * if it doesn't then it is broken or shorted and we return a 0;
hudakz 10:c89b9ad6097c 141 * @param
hudakz 10:c89b9ad6097c 142 * @retval 1 if a device asserted a presence pulse, 0 otherwise.
hudakz 10:c89b9ad6097c 143 */
hudakz 0:acf75feb0947 144 uint8_t OneWire::reset(void)
hudakz 0:acf75feb0947 145 {
hudakz 8:87fbdaba5535 146 uint8_t r;
hudakz 8:87fbdaba5535 147 uint8_t retries = 125;
hudakz 0:acf75feb0947 148
hudakz 9:4af0015b0f47 149 INPUT();
hudakz 0:acf75feb0947 150 // wait until the wire is high... just in case
hudakz 0:acf75feb0947 151 do {
hudakz 9:4af0015b0f47 152 if (--retries == 0)
hudakz 8:87fbdaba5535 153 return 0;
hudakz 0:acf75feb0947 154 wait_us(2);
hudakz 9:4af0015b0f47 155 } while (READ() != 1);
hudakz 0:acf75feb0947 156
hudakz 9:4af0015b0f47 157 OUTPUT();
hudakz 9:4af0015b0f47 158 WRITE(0);
hudakz 0:acf75feb0947 159 wait_us(480);
hudakz 9:4af0015b0f47 160 INPUT();
hudakz 9:4af0015b0f47 161 wait_us(65);
hudakz 9:4af0015b0f47 162 r = !READ();
hudakz 9:4af0015b0f47 163 wait_us(420);
hudakz 0:acf75feb0947 164 return r;
hudakz 0:acf75feb0947 165 }
hudakz 0:acf75feb0947 166
hudakz 10:c89b9ad6097c 167 /**
hudakz 10:c89b9ad6097c 168 * @brief Writes a bit.
hudakz 10:c89b9ad6097c 169 * @note GPIO registers are used for STM chips to cut time.
hudakz 10:c89b9ad6097c 170 * @param
hudakz 10:c89b9ad6097c 171 * @retval
hudakz 10:c89b9ad6097c 172 */
hudakz 0:acf75feb0947 173 void OneWire::write_bit(uint8_t v)
hudakz 0:acf75feb0947 174 {
hudakz 9:4af0015b0f47 175 OUTPUT();
hudakz 0:acf75feb0947 176 if (v & 1) {
hudakz 9:4af0015b0f47 177 WRITE(0); // drive output low
hudakz 9:4af0015b0f47 178 wait_us(1);
hudakz 9:4af0015b0f47 179 WRITE(1); // drive output high
hudakz 9:4af0015b0f47 180 wait_us(60);
hudakz 8:87fbdaba5535 181 }
hudakz 8:87fbdaba5535 182 else {
hudakz 9:4af0015b0f47 183 WRITE(0); // drive output low
hudakz 9:4af0015b0f47 184 wait_us(60);
hudakz 9:4af0015b0f47 185 WRITE(1); // drive output high
hudakz 9:4af0015b0f47 186 wait_us(1);
hudakz 0:acf75feb0947 187 }
hudakz 0:acf75feb0947 188 }
hudakz 0:acf75feb0947 189
hudakz 10:c89b9ad6097c 190 /**
hudakz 10:c89b9ad6097c 191 * @brief Reads a bit.
hudakz 10:c89b9ad6097c 192 * @note GPIO registers are used for STM chips to cut time.
hudakz 10:c89b9ad6097c 193 * @param
hudakz 10:c89b9ad6097c 194 * @retval
hudakz 10:c89b9ad6097c 195 */
hudakz 0:acf75feb0947 196 uint8_t OneWire::read_bit(void)
hudakz 0:acf75feb0947 197 {
hudakz 0:acf75feb0947 198 uint8_t r;
hudakz 7:acf3f0ee66d2 199 int t;
hudakz 0:acf75feb0947 200
hudakz 9:4af0015b0f47 201 OUTPUT();
hudakz 10:c89b9ad6097c 202 timer.start();
hudakz 9:4af0015b0f47 203 WRITE(0);
hudakz 9:4af0015b0f47 204 INPUT();
hudakz 7:acf3f0ee66d2 205 t = timer.read_us();
hudakz 8:87fbdaba5535 206 if (t < 7)
hudakz 8:87fbdaba5535 207 wait_us(7 - t);
hudakz 9:4af0015b0f47 208 r = READ();
hudakz 6:d6e084297fb9 209 timer.stop();
hudakz 6:d6e084297fb9 210 timer.reset();
hudakz 9:4af0015b0f47 211 wait_us(55);
hudakz 0:acf75feb0947 212 return r;
hudakz 0:acf75feb0947 213 }
hudakz 0:acf75feb0947 214
hudakz 10:c89b9ad6097c 215 /**
hudakz 10:c89b9ad6097c 216 * @brief Writes a byte.
hudakz 10:c89b9ad6097c 217 * @note The writing code uses the active drivers to raise the
hudakz 10:c89b9ad6097c 218 pin high, if you need power after the write (e.g. DS18S20 in
hudakz 10:c89b9ad6097c 219 parasite power mode) then set 'power' to 1, otherwise the pin will
hudakz 10:c89b9ad6097c 220 go tri-state at the end of the write to avoid heating in a short or
hudakz 10:c89b9ad6097c 221 other mishap.
hudakz 10:c89b9ad6097c 222 * @param
hudakz 10:c89b9ad6097c 223 * @retval
hudakz 10:c89b9ad6097c 224 */
hudakz 9:4af0015b0f47 225 void OneWire::write_byte(uint8_t v, uint8_t power /* = 0 */ )
hudakz 8:87fbdaba5535 226 {
hudakz 0:acf75feb0947 227 uint8_t bitMask;
hudakz 0:acf75feb0947 228
hudakz 9:4af0015b0f47 229 for (bitMask = 0x01; bitMask; bitMask <<= 1)
hudakz 9:4af0015b0f47 230 write_bit((bitMask & v) ? 1 : 0);
hudakz 8:87fbdaba5535 231 if (!power)
hudakz 9:4af0015b0f47 232 INPUT();
hudakz 0:acf75feb0947 233 }
hudakz 0:acf75feb0947 234
hudakz 8:87fbdaba5535 235 /**
hudakz 10:c89b9ad6097c 236 * @brief Writes bytes.
hudakz 8:87fbdaba5535 237 * @note
hudakz 8:87fbdaba5535 238 * @param
hudakz 8:87fbdaba5535 239 * @retval
hudakz 8:87fbdaba5535 240 */
hudakz 8:87fbdaba5535 241 void OneWire::write_bytes(const uint8_t* buf, uint16_t count, bool power /* = 0 */ )
hudakz 8:87fbdaba5535 242 {
hudakz 8:87fbdaba5535 243 for (uint16_t i = 0; i < count; i++)
hudakz 9:4af0015b0f47 244 write_byte(buf[i]);
hudakz 8:87fbdaba5535 245 if (!power)
hudakz 9:4af0015b0f47 246 INPUT();
hudakz 0:acf75feb0947 247 }
hudakz 0:acf75feb0947 248
hudakz 10:c89b9ad6097c 249 /**
hudakz 10:c89b9ad6097c 250 * @brief Reads a byte.
hudakz 10:c89b9ad6097c 251 * @note
hudakz 10:c89b9ad6097c 252 * @param
hudakz 10:c89b9ad6097c 253 * @retval
hudakz 10:c89b9ad6097c 254 */
hudakz 9:4af0015b0f47 255 uint8_t OneWire::read_byte()
hudakz 8:87fbdaba5535 256 {
hudakz 0:acf75feb0947 257 uint8_t bitMask;
hudakz 0:acf75feb0947 258 uint8_t r = 0;
hudakz 0:acf75feb0947 259
hudakz 0:acf75feb0947 260 for (bitMask = 0x01; bitMask; bitMask <<= 1) {
hudakz 9:4af0015b0f47 261 if (read_bit())
hudakz 8:87fbdaba5535 262 r |= bitMask;
hudakz 0:acf75feb0947 263 }
hudakz 8:87fbdaba5535 264
hudakz 0:acf75feb0947 265 return r;
hudakz 0:acf75feb0947 266 }
hudakz 0:acf75feb0947 267
hudakz 8:87fbdaba5535 268 /**
hudakz 10:c89b9ad6097c 269 * @brief Reads bytes.
hudakz 8:87fbdaba5535 270 * @note
hudakz 8:87fbdaba5535 271 * @param
hudakz 8:87fbdaba5535 272 * @retval
hudakz 8:87fbdaba5535 273 */
hudakz 8:87fbdaba5535 274 void OneWire::read_bytes(uint8_t* buf, uint16_t count)
hudakz 8:87fbdaba5535 275 {
hudakz 8:87fbdaba5535 276 for (uint16_t i = 0; i < count; i++)
hudakz 9:4af0015b0f47 277 buf[i] = read_byte();
hudakz 0:acf75feb0947 278 }
hudakz 0:acf75feb0947 279
hudakz 10:c89b9ad6097c 280 /**
hudakz 10:c89b9ad6097c 281 * @brief Selects ROM.
hudakz 10:c89b9ad6097c 282 * @note
hudakz 10:c89b9ad6097c 283 * @param
hudakz 10:c89b9ad6097c 284 * @retval
hudakz 10:c89b9ad6097c 285 */
hudakz 0:acf75feb0947 286 void OneWire::select(const uint8_t rom[8])
hudakz 0:acf75feb0947 287 {
hudakz 0:acf75feb0947 288 uint8_t i;
hudakz 0:acf75feb0947 289
hudakz 10:c89b9ad6097c 290 write_byte(0x55); // Choose ROM
hudakz 8:87fbdaba5535 291 for (i = 0; i < 8; i++)
hudakz 9:4af0015b0f47 292 write_byte(rom[i]);
hudakz 0:acf75feb0947 293 }
hudakz 0:acf75feb0947 294
hudakz 10:c89b9ad6097c 295 /**
hudakz 10:c89b9ad6097c 296 * @brief Skips ROM select.
hudakz 10:c89b9ad6097c 297 * @note
hudakz 10:c89b9ad6097c 298 * @param
hudakz 10:c89b9ad6097c 299 * @retval
hudakz 10:c89b9ad6097c 300 */
hudakz 0:acf75feb0947 301 void OneWire::skip()
hudakz 0:acf75feb0947 302 {
hudakz 10:c89b9ad6097c 303 write_byte(0xCC); // Skip ROM
hudakz 0:acf75feb0947 304 }
hudakz 0:acf75feb0947 305
hudakz 8:87fbdaba5535 306 /**
hudakz 10:c89b9ad6097c 307 * @brief Unpowers the chip.
hudakz 8:87fbdaba5535 308 * @note
hudakz 8:87fbdaba5535 309 * @param
hudakz 8:87fbdaba5535 310 * @retval
hudakz 8:87fbdaba5535 311 */
hudakz 0:acf75feb0947 312 void OneWire::depower()
hudakz 0:acf75feb0947 313 {
hudakz 9:4af0015b0f47 314 INPUT();
hudakz 0:acf75feb0947 315 }
hudakz 0:acf75feb0947 316
hudakz 0:acf75feb0947 317 #if ONEWIRE_SEARCH
hudakz 8:87fbdaba5535 318 //
hudakz 0:acf75feb0947 319
hudakz 10:c89b9ad6097c 320 /**
hudakz 10:c89b9ad6097c 321 * @brief Resets the search state.
hudakz 10:c89b9ad6097c 322 * @note We need to use this function to start a search again from the beginning.
hudakz 10:c89b9ad6097c 323 * We do not need to do it for the first search, though we could.
hudakz 10:c89b9ad6097c 324 * @param
hudakz 10:c89b9ad6097c 325 * @retval
hudakz 10:c89b9ad6097c 326 */
hudakz 0:acf75feb0947 327 void OneWire::reset_search()
hudakz 0:acf75feb0947 328 {
hudakz 8:87fbdaba5535 329 // reset the search state
hudakz 8:87fbdaba5535 330 LastDiscrepancy = 0;
hudakz 8:87fbdaba5535 331 LastDeviceFlag = false;
hudakz 8:87fbdaba5535 332 LastFamilyDiscrepancy = 0;
hudakz 8:87fbdaba5535 333 for (int i = 7;; i--) {
hudakz 8:87fbdaba5535 334 ROM_NO[i] = 0;
hudakz 8:87fbdaba5535 335 if (i == 0)
hudakz 8:87fbdaba5535 336 break;
hudakz 8:87fbdaba5535 337 }
hudakz 0:acf75feb0947 338 }
hudakz 0:acf75feb0947 339
hudakz 10:c89b9ad6097c 340 /**
hudakz 10:c89b9ad6097c 341 * @brief Sets the search state to find SearchFamily type devices.
hudakz 10:c89b9ad6097c 342 * @note
hudakz 10:c89b9ad6097c 343 * @param
hudakz 10:c89b9ad6097c 344 * @retval
hudakz 10:c89b9ad6097c 345 */
hudakz 0:acf75feb0947 346 void OneWire::target_search(uint8_t family_code)
hudakz 0:acf75feb0947 347 {
hudakz 8:87fbdaba5535 348 // set the search state to find SearchFamily type devices
hudakz 8:87fbdaba5535 349 ROM_NO[0] = family_code;
hudakz 8:87fbdaba5535 350 for (uint8_t i = 1; i < 8; i++)
hudakz 8:87fbdaba5535 351 ROM_NO[i] = 0;
hudakz 8:87fbdaba5535 352 LastDiscrepancy = 64;
hudakz 8:87fbdaba5535 353 LastFamilyDiscrepancy = 0;
hudakz 8:87fbdaba5535 354 LastDeviceFlag = false;
hudakz 0:acf75feb0947 355 }
hudakz 0:acf75feb0947 356
hudakz 10:c89b9ad6097c 357 /**
hudakz 10:c89b9ad6097c 358 * @brief Performs a search.
hudakz 10:c89b9ad6097c 359 * @note Perform a search. If this function returns a '1' then it has
hudakz 10:c89b9ad6097c 360 enumerated the next device and you may retrieve the ROM from the
hudakz 10:c89b9ad6097c 361 OneWire::address variable. If there are no devices, no further
hudakz 10:c89b9ad6097c 362 devices, or something horrible happens in the middle of the
hudakz 10:c89b9ad6097c 363 enumeration then a 0 is returned. If a new device is found then
hudakz 10:c89b9ad6097c 364 its address is copied to newAddr. Use OneWire::reset_search() to
hudakz 10:c89b9ad6097c 365 start over.
hudakz 10:c89b9ad6097c 366
hudakz 10:c89b9ad6097c 367 --- Replaced by the one from the Dallas Semiconductor web site ---
hudakz 10:c89b9ad6097c 368 -------------------------------------------------------------------------
hudakz 10:c89b9ad6097c 369 Perform the 1-Wire Search Algorithm on the 1-Wire bus using the existing
hudakz 10:c89b9ad6097c 370 search state.
hudakz 10:c89b9ad6097c 371 * @param
hudakz 10:c89b9ad6097c 372 * @retval true : device found, ROM number in ROM_NO buffer
hudakz 10:c89b9ad6097c 373 * false : device not found, end of search
hudakz 10:c89b9ad6097c 374 */
hudakz 8:87fbdaba5535 375 uint8_t OneWire::search(uint8_t* newAddr)
hudakz 0:acf75feb0947 376 {
hudakz 8:87fbdaba5535 377 uint8_t id_bit_number;
hudakz 8:87fbdaba5535 378 uint8_t last_zero, rom_byte_number, search_result;
hudakz 8:87fbdaba5535 379 uint8_t id_bit, cmp_id_bit;
hudakz 0:acf75feb0947 380
hudakz 8:87fbdaba5535 381 unsigned char rom_byte_mask, search_direction;
hudakz 0:acf75feb0947 382
hudakz 8:87fbdaba5535 383 // initialize for search
hudakz 8:87fbdaba5535 384 id_bit_number = 1;
hudakz 8:87fbdaba5535 385 last_zero = 0;
hudakz 8:87fbdaba5535 386 rom_byte_number = 0;
hudakz 8:87fbdaba5535 387 rom_byte_mask = 1;
hudakz 8:87fbdaba5535 388 search_result = 0;
hudakz 0:acf75feb0947 389
hudakz 8:87fbdaba5535 390 // if the last call was not the last one
hudakz 8:87fbdaba5535 391 if (!LastDeviceFlag) {
hudakz 8:87fbdaba5535 392 // 1-Wire reset
hudakz 8:87fbdaba5535 393 if (!reset()) {
hudakz 8:87fbdaba5535 394 // reset the search
hudakz 8:87fbdaba5535 395 LastDiscrepancy = 0;
hudakz 8:87fbdaba5535 396 LastDeviceFlag = false;
hudakz 8:87fbdaba5535 397 LastFamilyDiscrepancy = 0;
hudakz 8:87fbdaba5535 398 return false;
hudakz 8:87fbdaba5535 399 }
hudakz 0:acf75feb0947 400
hudakz 8:87fbdaba5535 401 // issue the search command
hudakz 9:4af0015b0f47 402 write_byte(0xF0);
hudakz 0:acf75feb0947 403
hudakz 8:87fbdaba5535 404 // loop to do the search
hudakz 8:87fbdaba5535 405 do {
hudakz 8:87fbdaba5535 406 // read a bit and its complement
hudakz 8:87fbdaba5535 407 id_bit = read_bit();
hudakz 8:87fbdaba5535 408 cmp_id_bit = read_bit();
hudakz 0:acf75feb0947 409
hudakz 8:87fbdaba5535 410 // check for no devices on 1-wire
hudakz 8:87fbdaba5535 411 if ((id_bit == 1) && (cmp_id_bit == 1))
hudakz 8:87fbdaba5535 412 break;
hudakz 8:87fbdaba5535 413 else {
hudakz 8:87fbdaba5535 414 // all devices coupled have 0 or 1
hudakz 8:87fbdaba5535 415 if (id_bit != cmp_id_bit)
hudakz 8:87fbdaba5535 416 search_direction = id_bit; // bit write value for search
hudakz 8:87fbdaba5535 417 else {
hudakz 8:87fbdaba5535 418 // if this discrepancy if before the Last Discrepancy
hudakz 8:87fbdaba5535 419 // on a previous next then pick the same as last time
hudakz 8:87fbdaba5535 420 if (id_bit_number < LastDiscrepancy)
hudakz 8:87fbdaba5535 421 search_direction = ((ROM_NO[rom_byte_number] & rom_byte_mask) > 0);
hudakz 8:87fbdaba5535 422 else
hudakz 8:87fbdaba5535 423 // if equal to last pick 1, if not then pick 0
hudakz 8:87fbdaba5535 424 search_direction = (id_bit_number == LastDiscrepancy);
hudakz 0:acf75feb0947 425
hudakz 8:87fbdaba5535 426 // if 0 was picked then record its position in LastZero
hudakz 8:87fbdaba5535 427 if (search_direction == 0) {
hudakz 8:87fbdaba5535 428 last_zero = id_bit_number;
hudakz 0:acf75feb0947 429
hudakz 8:87fbdaba5535 430 // check for Last discrepancy in family
hudakz 8:87fbdaba5535 431 if (last_zero < 9)
hudakz 8:87fbdaba5535 432 LastFamilyDiscrepancy = last_zero;
hudakz 8:87fbdaba5535 433 }
hudakz 8:87fbdaba5535 434 }
hudakz 0:acf75feb0947 435
hudakz 8:87fbdaba5535 436 // set or clear the bit in the ROM byte rom_byte_number
hudakz 8:87fbdaba5535 437 // with mask rom_byte_mask
hudakz 8:87fbdaba5535 438 if (search_direction == 1)
hudakz 8:87fbdaba5535 439 ROM_NO[rom_byte_number] |= rom_byte_mask;
hudakz 8:87fbdaba5535 440 else
hudakz 8:87fbdaba5535 441 ROM_NO[rom_byte_number] &= ~rom_byte_mask;
hudakz 0:acf75feb0947 442
hudakz 8:87fbdaba5535 443 // serial number search direction write bit
hudakz 8:87fbdaba5535 444 write_bit(search_direction);
hudakz 0:acf75feb0947 445
hudakz 8:87fbdaba5535 446 // increment the byte counter id_bit_number
hudakz 8:87fbdaba5535 447 // and shift the mask rom_byte_mask
hudakz 8:87fbdaba5535 448 id_bit_number++;
hudakz 8:87fbdaba5535 449 rom_byte_mask <<= 1;
hudakz 0:acf75feb0947 450
hudakz 8:87fbdaba5535 451 // if the mask is 0 then go to new SerialNum byte rom_byte_number and reset mask
hudakz 8:87fbdaba5535 452 if (rom_byte_mask == 0) {
hudakz 8:87fbdaba5535 453 rom_byte_number++;
hudakz 8:87fbdaba5535 454 rom_byte_mask = 1;
hudakz 8:87fbdaba5535 455 }
hudakz 0:acf75feb0947 456 }
hudakz 8:87fbdaba5535 457 } while (rom_byte_number < 8);
hudakz 8:87fbdaba5535 458 // loop until through all ROM bytes 0-7
hudakz 8:87fbdaba5535 459 // if the search was successful then
hudakz 8:87fbdaba5535 460 if (!(id_bit_number < 65)) {
hudakz 8:87fbdaba5535 461 // search successful so set LastDiscrepancy,LastDeviceFlag,search_result
hudakz 8:87fbdaba5535 462 LastDiscrepancy = last_zero;
hudakz 0:acf75feb0947 463
hudakz 8:87fbdaba5535 464 // check for last device
hudakz 8:87fbdaba5535 465 if (LastDiscrepancy == 0)
hudakz 8:87fbdaba5535 466 LastDeviceFlag = true;
hudakz 0:acf75feb0947 467
hudakz 8:87fbdaba5535 468 search_result = true;
hudakz 8:87fbdaba5535 469 }
hudakz 8:87fbdaba5535 470 }
hudakz 0:acf75feb0947 471
hudakz 8:87fbdaba5535 472 // if no device found then reset counters so next 'search' will be like a first
hudakz 8:87fbdaba5535 473 if (!search_result || !ROM_NO[0]) {
hudakz 8:87fbdaba5535 474 LastDiscrepancy = 0;
hudakz 8:87fbdaba5535 475 LastDeviceFlag = false;
hudakz 8:87fbdaba5535 476 LastFamilyDiscrepancy = 0;
hudakz 8:87fbdaba5535 477 search_result = false;
hudakz 8:87fbdaba5535 478 }
hudakz 0:acf75feb0947 479
hudakz 8:87fbdaba5535 480 for (int i = 0; i < 8; i++)
hudakz 8:87fbdaba5535 481 newAddr[i] = ROM_NO[i];
hudakz 8:87fbdaba5535 482 return search_result;
hudakz 8:87fbdaba5535 483 }
hudakz 0:acf75feb0947 484 #endif
hudakz 10:c89b9ad6097c 485 //
hudakz 0:acf75feb0947 486 #if ONEWIRE_CRC
hudakz 0:acf75feb0947 487 //
hudakz 10:c89b9ad6097c 488 /**
hudakz 10:c89b9ad6097c 489 * @brief Computes a Dallas Semiconductor 8 bit CRC directly.
hudakz 10:c89b9ad6097c 490 * @note The 1-Wire CRC scheme is described in Maxim Application Note 27:
hudakz 10:c89b9ad6097c 491 "Understanding and Using Cyclic Redundancy Checks with Maxim iButton Products"
hudakz 10:c89b9ad6097c 492 * @param
hudakz 10:c89b9ad6097c 493 * @retval
hudakz 10:c89b9ad6097c 494 */
hudakz 8:87fbdaba5535 495 uint8_t OneWire::crc8(const uint8_t* addr, uint8_t len)
hudakz 0:acf75feb0947 496 {
hudakz 0:acf75feb0947 497 uint8_t crc = 0;
hudakz 8:87fbdaba5535 498
hudakz 0:acf75feb0947 499 while (len--) {
hudakz 0:acf75feb0947 500 uint8_t inbyte = *addr++;
hudakz 0:acf75feb0947 501 for (uint8_t i = 8; i; i--) {
hudakz 0:acf75feb0947 502 uint8_t mix = (crc ^ inbyte) & 0x01;
hudakz 0:acf75feb0947 503 crc >>= 1;
hudakz 8:87fbdaba5535 504 if (mix)
hudakz 8:87fbdaba5535 505 crc ^= 0x8C;
hudakz 0:acf75feb0947 506 inbyte >>= 1;
hudakz 0:acf75feb0947 507 }
hudakz 0:acf75feb0947 508 }
hudakz 8:87fbdaba5535 509
hudakz 0:acf75feb0947 510 return crc;
hudakz 0:acf75feb0947 511 }
hudakz 0:acf75feb0947 512 #endif