Zoltan Hudak / OneWire

Dallas' 1-Wire bus protocol library

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

OneWire.cpp@11:bc8ed7280966, 2019-01-27 (annotated)

Committer:
hudakz
Date:
Sun Jan 27 18:01:19 2019 +0000
Revision:
11:bc8ed7280966
Parent:
10:c89b9ad6097c
Child:
12:27a1b359b95c
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 11:bc8ed7280966 129 MODE(); // set mode either PullUp or OpenDrain for STM
hudakz 0:acf75feb0947 130 #if ONEWIRE_SEARCH
hudakz 0:acf75feb0947 131 reset_search();
hudakz 0:acf75feb0947 132 #endif
hudakz 0:acf75feb0947 133 }
hudakz 0:acf75feb0947 134
hudakz 10:c89b9ad6097c 135 /**
hudakz 10:c89b9ad6097c 136 * @brief Performs the onewire reset function.
hudakz 10:c89b9ad6097c 137 * @note We will wait up to 250uS for the bus to come high,
hudakz 10:c89b9ad6097c 138 * if it doesn't then it is broken or shorted and we return a 0;
hudakz 10:c89b9ad6097c 139 * @param
hudakz 10:c89b9ad6097c 140 * @retval 1 if a device asserted a presence pulse, 0 otherwise.
hudakz 10:c89b9ad6097c 141 */
hudakz 0:acf75feb0947 142 uint8_t OneWire::reset(void)
hudakz 0:acf75feb0947 143 {
hudakz 8:87fbdaba5535 144 uint8_t r;
hudakz 8:87fbdaba5535 145 uint8_t retries = 125;
hudakz 0:acf75feb0947 146
hudakz 9:4af0015b0f47 147 INPUT();
hudakz 0:acf75feb0947 148 // wait until the wire is high... just in case
hudakz 0:acf75feb0947 149 do {
hudakz 9:4af0015b0f47 150 if (--retries == 0)
hudakz 8:87fbdaba5535 151 return 0;
hudakz 0:acf75feb0947 152 wait_us(2);
hudakz 11:bc8ed7280966 153 } while (READ() == 0);
hudakz 0:acf75feb0947 154
hudakz 9:4af0015b0f47 155 OUTPUT();
hudakz 9:4af0015b0f47 156 WRITE(0);
hudakz 0:acf75feb0947 157 wait_us(480);
hudakz 9:4af0015b0f47 158 INPUT();
hudakz 9:4af0015b0f47 159 wait_us(65);
hudakz 9:4af0015b0f47 160 r = !READ();
hudakz 9:4af0015b0f47 161 wait_us(420);
hudakz 0:acf75feb0947 162 return r;
hudakz 0:acf75feb0947 163 }
hudakz 0:acf75feb0947 164
hudakz 10:c89b9ad6097c 165 /**
hudakz 10:c89b9ad6097c 166 * @brief Writes a bit.
hudakz 10:c89b9ad6097c 167 * @note GPIO registers are used for STM chips to cut time.
hudakz 10:c89b9ad6097c 168 * @param
hudakz 10:c89b9ad6097c 169 * @retval
hudakz 10:c89b9ad6097c 170 */
hudakz 0:acf75feb0947 171 void OneWire::write_bit(uint8_t v)
hudakz 0:acf75feb0947 172 {
hudakz 9:4af0015b0f47 173 OUTPUT();
hudakz 0:acf75feb0947 174 if (v & 1) {
hudakz 9:4af0015b0f47 175 WRITE(0); // drive output low
hudakz 9:4af0015b0f47 176 wait_us(1);
hudakz 9:4af0015b0f47 177 WRITE(1); // drive output high
hudakz 9:4af0015b0f47 178 wait_us(60);
hudakz 8:87fbdaba5535 179 }
hudakz 8:87fbdaba5535 180 else {
hudakz 9:4af0015b0f47 181 WRITE(0); // drive output low
hudakz 9:4af0015b0f47 182 wait_us(60);
hudakz 9:4af0015b0f47 183 WRITE(1); // drive output high
hudakz 9:4af0015b0f47 184 wait_us(1);
hudakz 0:acf75feb0947 185 }
hudakz 0:acf75feb0947 186 }
hudakz 0:acf75feb0947 187
hudakz 10:c89b9ad6097c 188 /**
hudakz 10:c89b9ad6097c 189 * @brief Reads a bit.
hudakz 10:c89b9ad6097c 190 * @note GPIO registers are used for STM chips to cut time.
hudakz 10:c89b9ad6097c 191 * @param
hudakz 10:c89b9ad6097c 192 * @retval
hudakz 10:c89b9ad6097c 193 */
hudakz 0:acf75feb0947 194 uint8_t OneWire::read_bit(void)
hudakz 0:acf75feb0947 195 {
hudakz 0:acf75feb0947 196 uint8_t r;
hudakz 7:acf3f0ee66d2 197 int t;
hudakz 0:acf75feb0947 198
hudakz 9:4af0015b0f47 199 OUTPUT();
hudakz 10:c89b9ad6097c 200 timer.start();
hudakz 9:4af0015b0f47 201 WRITE(0);
hudakz 9:4af0015b0f47 202 INPUT();
hudakz 7:acf3f0ee66d2 203 t = timer.read_us();
hudakz 8:87fbdaba5535 204 if (t < 7)
hudakz 8:87fbdaba5535 205 wait_us(7 - t);
hudakz 9:4af0015b0f47 206 r = READ();
hudakz 6:d6e084297fb9 207 timer.stop();
hudakz 6:d6e084297fb9 208 timer.reset();
hudakz 9:4af0015b0f47 209 wait_us(55);
hudakz 0:acf75feb0947 210 return r;
hudakz 0:acf75feb0947 211 }
hudakz 0:acf75feb0947 212
hudakz 10:c89b9ad6097c 213 /**
hudakz 10:c89b9ad6097c 214 * @brief Writes a byte.
hudakz 10:c89b9ad6097c 215 * @note The writing code uses the active drivers to raise the
hudakz 10:c89b9ad6097c 216 pin high, if you need power after the write (e.g. DS18S20 in
hudakz 10:c89b9ad6097c 217 parasite power mode) then set 'power' to 1, otherwise the pin will
hudakz 10:c89b9ad6097c 218 go tri-state at the end of the write to avoid heating in a short or
hudakz 10:c89b9ad6097c 219 other mishap.
hudakz 10:c89b9ad6097c 220 * @param
hudakz 10:c89b9ad6097c 221 * @retval
hudakz 10:c89b9ad6097c 222 */
hudakz 9:4af0015b0f47 223 void OneWire::write_byte(uint8_t v, uint8_t power /* = 0 */ )
hudakz 8:87fbdaba5535 224 {
hudakz 0:acf75feb0947 225 uint8_t bitMask;
hudakz 0:acf75feb0947 226
hudakz 9:4af0015b0f47 227 for (bitMask = 0x01; bitMask; bitMask <<= 1)
hudakz 9:4af0015b0f47 228 write_bit((bitMask & v) ? 1 : 0);
hudakz 8:87fbdaba5535 229 if (!power)
hudakz 9:4af0015b0f47 230 INPUT();
hudakz 0:acf75feb0947 231 }
hudakz 0:acf75feb0947 232
hudakz 8:87fbdaba5535 233 /**
hudakz 10:c89b9ad6097c 234 * @brief Writes bytes.
hudakz 8:87fbdaba5535 235 * @note
hudakz 8:87fbdaba5535 236 * @param
hudakz 8:87fbdaba5535 237 * @retval
hudakz 8:87fbdaba5535 238 */
hudakz 8:87fbdaba5535 239 void OneWire::write_bytes(const uint8_t* buf, uint16_t count, bool power /* = 0 */ )
hudakz 8:87fbdaba5535 240 {
hudakz 8:87fbdaba5535 241 for (uint16_t i = 0; i < count; i++)
hudakz 9:4af0015b0f47 242 write_byte(buf[i]);
hudakz 8:87fbdaba5535 243 if (!power)
hudakz 9:4af0015b0f47 244 INPUT();
hudakz 0:acf75feb0947 245 }
hudakz 0:acf75feb0947 246
hudakz 10:c89b9ad6097c 247 /**
hudakz 10:c89b9ad6097c 248 * @brief Reads a byte.
hudakz 10:c89b9ad6097c 249 * @note
hudakz 10:c89b9ad6097c 250 * @param
hudakz 10:c89b9ad6097c 251 * @retval
hudakz 10:c89b9ad6097c 252 */
hudakz 9:4af0015b0f47 253 uint8_t OneWire::read_byte()
hudakz 8:87fbdaba5535 254 {
hudakz 0:acf75feb0947 255 uint8_t bitMask;
hudakz 0:acf75feb0947 256 uint8_t r = 0;
hudakz 0:acf75feb0947 257
hudakz 0:acf75feb0947 258 for (bitMask = 0x01; bitMask; bitMask <<= 1) {
hudakz 9:4af0015b0f47 259 if (read_bit())
hudakz 8:87fbdaba5535 260 r |= bitMask;
hudakz 0:acf75feb0947 261 }
hudakz 8:87fbdaba5535 262
hudakz 0:acf75feb0947 263 return r;
hudakz 0:acf75feb0947 264 }
hudakz 0:acf75feb0947 265
hudakz 8:87fbdaba5535 266 /**
hudakz 10:c89b9ad6097c 267 * @brief Reads bytes.
hudakz 8:87fbdaba5535 268 * @note
hudakz 8:87fbdaba5535 269 * @param
hudakz 8:87fbdaba5535 270 * @retval
hudakz 8:87fbdaba5535 271 */
hudakz 8:87fbdaba5535 272 void OneWire::read_bytes(uint8_t* buf, uint16_t count)
hudakz 8:87fbdaba5535 273 {
hudakz 8:87fbdaba5535 274 for (uint16_t i = 0; i < count; i++)
hudakz 9:4af0015b0f47 275 buf[i] = read_byte();
hudakz 0:acf75feb0947 276 }
hudakz 0:acf75feb0947 277
hudakz 10:c89b9ad6097c 278 /**
hudakz 10:c89b9ad6097c 279 * @brief Selects ROM.
hudakz 10:c89b9ad6097c 280 * @note
hudakz 10:c89b9ad6097c 281 * @param
hudakz 10:c89b9ad6097c 282 * @retval
hudakz 10:c89b9ad6097c 283 */
hudakz 0:acf75feb0947 284 void OneWire::select(const uint8_t rom[8])
hudakz 0:acf75feb0947 285 {
hudakz 0:acf75feb0947 286 uint8_t i;
hudakz 0:acf75feb0947 287
hudakz 10:c89b9ad6097c 288 write_byte(0x55); // Choose ROM
hudakz 8:87fbdaba5535 289 for (i = 0; i < 8; i++)
hudakz 9:4af0015b0f47 290 write_byte(rom[i]);
hudakz 0:acf75feb0947 291 }
hudakz 0:acf75feb0947 292
hudakz 10:c89b9ad6097c 293 /**
hudakz 10:c89b9ad6097c 294 * @brief Skips ROM select.
hudakz 10:c89b9ad6097c 295 * @note
hudakz 10:c89b9ad6097c 296 * @param
hudakz 10:c89b9ad6097c 297 * @retval
hudakz 10:c89b9ad6097c 298 */
hudakz 0:acf75feb0947 299 void OneWire::skip()
hudakz 0:acf75feb0947 300 {
hudakz 10:c89b9ad6097c 301 write_byte(0xCC); // Skip ROM
hudakz 0:acf75feb0947 302 }
hudakz 0:acf75feb0947 303
hudakz 8:87fbdaba5535 304 /**
hudakz 10:c89b9ad6097c 305 * @brief Unpowers the chip.
hudakz 8:87fbdaba5535 306 * @note
hudakz 8:87fbdaba5535 307 * @param
hudakz 8:87fbdaba5535 308 * @retval
hudakz 8:87fbdaba5535 309 */
hudakz 0:acf75feb0947 310 void OneWire::depower()
hudakz 0:acf75feb0947 311 {
hudakz 9:4af0015b0f47 312 INPUT();
hudakz 0:acf75feb0947 313 }
hudakz 0:acf75feb0947 314
hudakz 0:acf75feb0947 315 #if ONEWIRE_SEARCH
hudakz 8:87fbdaba5535 316 //
hudakz 0:acf75feb0947 317
hudakz 10:c89b9ad6097c 318 /**
hudakz 10:c89b9ad6097c 319 * @brief Resets the search state.
hudakz 10:c89b9ad6097c 320 * @note We need to use this function to start a search again from the beginning.
hudakz 10:c89b9ad6097c 321 * We do not need to do it for the first search, though we could.
hudakz 10:c89b9ad6097c 322 * @param
hudakz 10:c89b9ad6097c 323 * @retval
hudakz 10:c89b9ad6097c 324 */
hudakz 0:acf75feb0947 325 void OneWire::reset_search()
hudakz 0:acf75feb0947 326 {
hudakz 8:87fbdaba5535 327 // reset the search state
hudakz 8:87fbdaba5535 328 LastDiscrepancy = 0;
hudakz 8:87fbdaba5535 329 LastDeviceFlag = false;
hudakz 8:87fbdaba5535 330 LastFamilyDiscrepancy = 0;
hudakz 8:87fbdaba5535 331 for (int i = 7;; i--) {
hudakz 8:87fbdaba5535 332 ROM_NO[i] = 0;
hudakz 8:87fbdaba5535 333 if (i == 0)
hudakz 8:87fbdaba5535 334 break;
hudakz 8:87fbdaba5535 335 }
hudakz 0:acf75feb0947 336 }
hudakz 0:acf75feb0947 337
hudakz 10:c89b9ad6097c 338 /**
hudakz 10:c89b9ad6097c 339 * @brief Sets the search state to find SearchFamily type devices.
hudakz 10:c89b9ad6097c 340 * @note
hudakz 10:c89b9ad6097c 341 * @param
hudakz 10:c89b9ad6097c 342 * @retval
hudakz 10:c89b9ad6097c 343 */
hudakz 0:acf75feb0947 344 void OneWire::target_search(uint8_t family_code)
hudakz 0:acf75feb0947 345 {
hudakz 8:87fbdaba5535 346 // set the search state to find SearchFamily type devices
hudakz 8:87fbdaba5535 347 ROM_NO[0] = family_code;
hudakz 8:87fbdaba5535 348 for (uint8_t i = 1; i < 8; i++)
hudakz 8:87fbdaba5535 349 ROM_NO[i] = 0;
hudakz 8:87fbdaba5535 350 LastDiscrepancy = 64;
hudakz 8:87fbdaba5535 351 LastFamilyDiscrepancy = 0;
hudakz 8:87fbdaba5535 352 LastDeviceFlag = false;
hudakz 0:acf75feb0947 353 }
hudakz 0:acf75feb0947 354
hudakz 10:c89b9ad6097c 355 /**
hudakz 10:c89b9ad6097c 356 * @brief Performs a search.
hudakz 10:c89b9ad6097c 357 * @note Perform a search. If this function returns a '1' then it has
hudakz 10:c89b9ad6097c 358 enumerated the next device and you may retrieve the ROM from the
hudakz 10:c89b9ad6097c 359 OneWire::address variable. If there are no devices, no further
hudakz 10:c89b9ad6097c 360 devices, or something horrible happens in the middle of the
hudakz 10:c89b9ad6097c 361 enumeration then a 0 is returned. If a new device is found then
hudakz 10:c89b9ad6097c 362 its address is copied to newAddr. Use OneWire::reset_search() to
hudakz 10:c89b9ad6097c 363 start over.
hudakz 10:c89b9ad6097c 364
hudakz 10:c89b9ad6097c 365 --- Replaced by the one from the Dallas Semiconductor web site ---
hudakz 10:c89b9ad6097c 366 -------------------------------------------------------------------------
hudakz 10:c89b9ad6097c 367 Perform the 1-Wire Search Algorithm on the 1-Wire bus using the existing
hudakz 10:c89b9ad6097c 368 search state.
hudakz 10:c89b9ad6097c 369 * @param
hudakz 10:c89b9ad6097c 370 * @retval true : device found, ROM number in ROM_NO buffer
hudakz 10:c89b9ad6097c 371 * false : device not found, end of search
hudakz 10:c89b9ad6097c 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 10:c89b9ad6097c 483 //
hudakz 0:acf75feb0947 484 #if ONEWIRE_CRC
hudakz 0:acf75feb0947 485 //
hudakz 10:c89b9ad6097c 486 /**
hudakz 10:c89b9ad6097c 487 * @brief Computes a Dallas Semiconductor 8 bit CRC directly.
hudakz 10:c89b9ad6097c 488 * @note The 1-Wire CRC scheme is described in Maxim Application Note 27:
hudakz 10:c89b9ad6097c 489 "Understanding and Using Cyclic Redundancy Checks with Maxim iButton Products"
hudakz 10:c89b9ad6097c 490 * @param
hudakz 10:c89b9ad6097c 491 * @retval
hudakz 10:c89b9ad6097c 492 */
hudakz 8:87fbdaba5535 493 uint8_t OneWire::crc8(const uint8_t* addr, uint8_t len)
hudakz 0:acf75feb0947 494 {
hudakz 0:acf75feb0947 495 uint8_t crc = 0;
hudakz 8:87fbdaba5535 496
hudakz 0:acf75feb0947 497 while (len--) {
hudakz 0:acf75feb0947 498 uint8_t inbyte = *addr++;
hudakz 0:acf75feb0947 499 for (uint8_t i = 8; i; i--) {
hudakz 0:acf75feb0947 500 uint8_t mix = (crc ^ inbyte) & 0x01;
hudakz 0:acf75feb0947 501 crc >>= 1;
hudakz 8:87fbdaba5535 502 if (mix)
hudakz 8:87fbdaba5535 503 crc ^= 0x8C;
hudakz 0:acf75feb0947 504 inbyte >>= 1;
hudakz 0:acf75feb0947 505 }
hudakz 0:acf75feb0947 506 }
hudakz 8:87fbdaba5535 507
hudakz 0:acf75feb0947 508 return crc;
hudakz 0:acf75feb0947 509 }
hudakz 0:acf75feb0947 510 #endif