Mercurial > ~darius > hgwebdir.cgi > avr
annotate 1wire.c @ 32:b0cb873c0206
Isolate the bus frobbing parts and the delays into a separate header.
This means the user only has to edit a single file to suit their
situation and allows the code to work with active drive systems as
well as passive pullups (ie 1 vs 2 IO pins)
| author | darius |
|---|---|
| date | Sun, 23 Apr 2006 22:57:16 +0930 |
| parents | 02b67e09ca12 |
| children | 0aa6bf4b98ae |
| rev | line source |
|---|---|
| 0 | 1 /* |
| 2 * Various 1 wire routines | |
| 12 | 3 * Search routine is copied from the Dallas owpd library with mods |
| 4 * available from here http://www.ibutton.com/software/1wire/wirekit.html | |
| 0 | 5 * |
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6 * $Id$ |
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7 * |
| 0 | 8 * Copyright (c) 2004 |
| 9 * Daniel O'Connor <darius@dons.net.au>. All rights reserved. | |
| 10 * | |
| 11 * Redistribution and use in source and binary forms, with or without | |
| 12 * modification, are permitted provided that the following conditions | |
| 13 * are met: | |
| 14 * 1. Redistributions of source code must retain the above copyright | |
| 15 * notice, this list of conditions and the following disclaimer. | |
| 16 * 2. Redistributions in binary form must reproduce the above copyright | |
| 17 * notice, this list of conditions and the following disclaimer in the | |
| 18 * documentation and/or other materials provided with the distribution. | |
| 19 * | |
| 20 * THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND | |
| 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
| 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
| 23 * ARE DISCLAIMED. IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE | |
| 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
| 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |
| 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
| 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
| 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | |
| 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
| 30 * SUCH DAMAGE. | |
| 31 */ | |
| 32 | |
|
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33 /* |
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34 * No user servicable parts inside |
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35 * |
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36 * Modify 1wire-config.h |
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37 */ |
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38 |
| 0 | 39 #include <stdio.h> |
| 40 #include <avr/io.h> | |
| 41 #include <avr/pgmspace.h> | |
| 21 | 42 #include <util/delay.h> |
| 0 | 43 #include "1wire.h" |
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44 #include "1wire-config.h" |
| 0 | 45 |
| 12 | 46 #if OW_DEBUG |
| 0 | 47 void uart_putsP(const char *addr); |
| 48 void uart_puts(const char *addr); | |
| 49 void uart_getc(); | |
| 21 | 50 char uart_putc(char c); |
| 12 | 51 #endif |
| 0 | 52 |
| 53 static uint8_t OW_LastDevice = 0; | |
| 54 static uint8_t OW_LastDiscrepancy = 0; | |
| 55 static uint8_t OW_LastFamilyDiscrepancy = 0; | |
| 56 | |
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57 /*----------------------------------------------------------------------------- |
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58 * Configure the IO port as we need |
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59 */ |
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60 void |
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61 OWInit(void) { |
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62 OWBUSINIT(); |
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63 OWSETBUSHIGH(); |
| 0 | 64 } |
| 65 | |
| 66 /*----------------------------------------------------------------------------- | |
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67 * Generate a 1-Wire reset, return 0 if presence pulse was found, 1 if it |
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68 * wasn't, or 2 if the line appears to be being held low. |
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69 * |
| 0 | 70 * (NOTE: Does not handle alarm presence from DS2404/DS1994) |
| 71 */ | |
| 12 | 72 uint8_t |
| 0 | 73 OWTouchReset(void) { |
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74 OWDELAY_G; |
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75 |
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76 /* Check the bus isn't being held low (ie it's broken) Do it after |
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77 * the delay so we guarantee we don't see a slave from a previous |
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78 * comms attempt |
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79 */ |
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80 if(OWREADBUS() == 0) |
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81 return 2; |
| 0 | 82 |
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83 OWSETBUSLOW(); |
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84 OWDELAY_H; |
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85 OWSETBUSHIGH(); |
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86 OWDELAY_I; |
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87 |
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88 return(OWREADBUS()); |
| 0 | 89 } |
| 90 | |
| 91 /*----------------------------------------------------------------------------- | |
| 92 * Send a 1-wire write bit. | |
| 93 */ | |
| 94 void | |
| 12 | 95 OWWriteBit(uint8_t bit) { |
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96 OWDELAY_I; |
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97 |
| 0 | 98 if (bit) { |
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99 OWSETBUSLOW(); |
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100 OWDELAY_A; |
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101 OWSETBUSHIGH(); |
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102 OWDELAY_B; |
| 0 | 103 } else { |
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104 OWSETBUSLOW(); |
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105 OWDELAY_C; |
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106 OWSETBUSHIGH(); |
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107 OWDELAY_D; |
| 0 | 108 } |
| 109 } | |
| 110 | |
| 111 /*----------------------------------------------------------------------------- | |
| 112 * Read a bit from the 1-wire bus and return it. | |
| 113 */ | |
| 12 | 114 uint8_t |
| 0 | 115 OWReadBit(void) { |
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116 OWDELAY_I; |
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117 |
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118 OWSETBUSLOW(); |
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119 OWDELAY_A; |
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120 OWSETBUSHIGH(); |
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121 OWDELAY_E; |
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122 return(OWREADBUS()); |
| 0 | 123 } |
| 124 | |
| 125 /*----------------------------------------------------------------------------- | |
| 126 * Write a byte to the 1-wire bus | |
| 127 */ | |
| 128 void | |
| 129 OWWriteByte(uint8_t data) { | |
| 12 | 130 uint8_t i; |
| 0 | 131 |
| 132 /* Send LSB first */ | |
| 133 for (i = 0; i < 8; i++) { | |
| 134 OWWriteBit(data & 0x01); | |
| 135 data >>= 1; | |
| 136 } | |
| 137 } | |
| 138 | |
| 139 /*----------------------------------------------------------------------------- | |
| 140 * Read a byte from the 1-wire bus | |
| 141 */ | |
| 12 | 142 uint8_t |
| 0 | 143 OWReadByte(void) { |
| 144 int i, result = 0; | |
| 145 | |
| 146 for (i = 0; i < 8; i++) { | |
| 147 result >>= 1; | |
| 148 if (OWReadBit()) | |
| 149 result |= 0x80; | |
| 150 } | |
| 151 return(result); | |
| 152 } | |
| 153 | |
| 154 /*----------------------------------------------------------------------------- | |
| 155 * Write a 1-wire data byte and return the sampled result. | |
| 156 */ | |
| 12 | 157 uint8_t |
| 0 | 158 OWTouchByte(uint8_t data) { |
| 12 | 159 uint8_t i, result = 0; |
| 0 | 160 |
| 161 for (i = 0; i < 8; i++) { | |
| 162 result >>= 1; | |
| 163 | |
| 164 /* If sending a 1 then read a bit, otherwise write a 0 */ | |
| 165 if (data & 0x01) { | |
| 166 if (OWReadBit()) | |
| 167 result |= 0x80; | |
| 168 } else | |
| 169 OWWriteBit(0); | |
| 170 | |
| 171 data >>= 1; | |
| 172 } | |
| 173 | |
| 174 return(result); | |
| 175 } | |
| 176 | |
| 177 /*----------------------------------------------------------------------------- | |
| 178 * Write a block of bytes to the 1-wire bus and return the sampled result in | |
| 179 * the same buffer | |
| 180 */ | |
| 181 void | |
| 182 OWBlock(uint8_t *data, int len) { | |
| 183 int i; | |
| 184 | |
| 185 for (i = 0; i < len; i++) | |
| 186 data[i] = OWTouchByte(data[i]); | |
| 187 } | |
| 188 | |
| 189 | |
| 190 /*----------------------------------------------------------------------------- | |
| 191 * Send a 1 wire command to a device, or all if no ROM ID provided | |
| 192 */ | |
| 193 void | |
| 194 OWSendCmd(uint8_t *ROM, uint8_t cmd) { | |
| 12 | 195 uint8_t i; |
| 0 | 196 |
| 197 OWTouchReset(); | |
| 198 | |
| 199 if (ROM == NULL) | |
| 200 OWWriteByte(OW_SKIP_ROM_CMD); | |
| 201 else { | |
| 202 OWWriteByte(OW_MATCH_ROM_CMD); | |
| 203 for (i = 0; i < 8; i++) | |
| 204 OWWriteByte(ROM[i]); | |
| 205 } | |
| 206 OWWriteByte(cmd); | |
| 207 } | |
| 208 | |
| 209 /*----------------------------------------------------------------------------- | |
| 210 * Search algorithm from App note 187 (and 162) | |
| 211 * | |
| 10 | 212 * OWFirst/OWNext return.. |
| 213 * 1 when something is found, | |
| 214 * 0 no more modules | |
| 16 | 215 * -1 if no presence pulse, |
| 10 | 216 * -2 if bad CRC, |
| 217 * -3 if bad wiring. | |
| 0 | 218 */ |
| 12 | 219 uint8_t |
| 0 | 220 OWFirst(uint8_t *ROM, uint8_t do_reset, uint8_t alarm_only) { |
| 221 /* Reset state */ | |
| 222 OW_LastDiscrepancy = 0; | |
| 223 OW_LastDevice = 0; | |
| 224 OW_LastFamilyDiscrepancy = 0; | |
| 225 | |
| 226 /* Go looking */ | |
| 227 return (OWNext(ROM, do_reset, alarm_only)); | |
| 228 } | |
| 229 | |
| 230 /* Returns 1 when something is found, 0 if nothing left */ | |
| 12 | 231 uint8_t |
| 0 | 232 OWNext(uint8_t *ROM, uint8_t do_reset, uint8_t alarm_only) { |
| 233 uint8_t bit_test, search_direction, bit_number; | |
| 10 | 234 uint8_t last_zero, rom_byte_number, rom_byte_mask; |
| 0 | 235 uint8_t lastcrc8, crcaccum; |
| 12 | 236 int8_t next_result; |
| 0 | 237 |
| 238 /* Init for search */ | |
| 21 | 239 bit_number = 1; |
| 240 last_zero = 0; | |
| 241 rom_byte_number = 0; | |
| 242 rom_byte_mask = 1; | |
| 243 next_result = OW_NOMODULES; | |
| 244 lastcrc8 = 0; | |
| 245 crcaccum = 0; | |
| 0 | 246 |
| 21 | 247 /* if the last call was not the last one */ |
| 248 if (!OW_LastDevice) { | |
| 249 /* check if reset first is requested */ | |
| 250 if (do_reset) { | |
| 251 /* reset the 1-wire | |
| 252 * if there are no parts on 1-wire, return 0 */ | |
| 0 | 253 #if OW_DEBUG |
| 21 | 254 uart_putsP(PSTR("Resetting\n\r")); |
| 0 | 255 #endif |
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256 switch (OWTouchReset()) { |
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257 case 0: |
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258 break; |
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259 |
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260 case 1: |
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261 /* reset the search */ |
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262 OW_LastDiscrepancy = 0; |
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263 OW_LastFamilyDiscrepancy = 0; |
| 0 | 264 #if OW_DEBUG |
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265 uart_putsP(PSTR("No devices on bus\n\r")); |
| 0 | 266 #endif |
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267 return OW_NOPRESENCE; |
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268 break; |
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269 |
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270 case 2: |
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271 /* reset the search */ |
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272 OW_LastDiscrepancy = 0; |
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273 OW_LastFamilyDiscrepancy = 0; |
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274 #if OW_DEBUG |
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275 uart_putsP(PSTR("Bus appears to be being held low\n\r")); |
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276 #endif |
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277 return OW_BADWIRE; |
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278 break; |
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279 |
| 21 | 280 } |
| 281 } | |
| 0 | 282 |
| 21 | 283 /* If finding alarming devices issue a different command */ |
| 284 if (alarm_only) | |
| 285 OWWriteByte(OW_SEARCH_ALRM_CMD); /* issue the alarming search command */ | |
| 286 else | |
| 287 OWWriteByte(OW_SEARCH_ROM_CMD); /* issue the search command */ | |
| 0 | 288 |
| 21 | 289 /* pause before beginning the search */ |
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290 OWDELAY_I; |
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291 OWDELAY_I; |
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292 OWDELAY_I; |
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293 |
| 21 | 294 /* loop to do the search */ |
| 295 do { | |
| 296 /* read a bit and its compliment */ | |
| 297 bit_test = OWReadBit() << 1; | |
| 298 bit_test |= OWReadBit(); | |
| 0 | 299 |
| 300 #if OW_DEBUG | |
| 21 | 301 sprintf_P(errstr, PSTR("bit_test = %d\n\r"), bit_test); |
| 302 uart_puts(errstr); | |
| 0 | 303 #endif |
| 304 | |
| 21 | 305 /* check for no devices on 1-wire */ |
| 306 if (bit_test == 3) { | |
| 10 | 307 #if OW_DEBUG |
| 21 | 308 sprintf_P(errstr, PSTR("bit_test = %d\n\r"), bit_test); |
| 309 uart_puts(errstr); | |
| 10 | 310 #endif |
| 21 | 311 return(OW_BADWIRE); |
| 312 } | |
| 313 else { | |
| 314 /* all devices coupled have 0 or 1 */ | |
| 315 if (bit_test > 0) | |
| 316 search_direction = !(bit_test & 0x01); /* bit write value for search */ | |
| 317 else { | |
| 318 /* if this discrepancy is before the Last Discrepancy | |
| 319 * on a previous OWNext then pick the same as last time */ | |
| 320 if (bit_number < OW_LastDiscrepancy) | |
| 321 search_direction = ((ROM[rom_byte_number] & rom_byte_mask) > 0); | |
| 322 else | |
| 323 /* if equal to last pick 1, if not then pick 0 */ | |
| 324 search_direction = (bit_number == OW_LastDiscrepancy); | |
| 0 | 325 |
| 21 | 326 /* if 0 was picked then record its position in LastZero */ |
| 327 if (search_direction == 0) { | |
| 328 last_zero = bit_number; | |
| 0 | 329 |
| 21 | 330 /* check for Last discrepancy in family */ |
| 331 if (last_zero < 9) | |
| 332 OW_LastFamilyDiscrepancy = last_zero; | |
| 333 } | |
| 334 } | |
| 0 | 335 |
| 21 | 336 /* set or clear the bit in the ROM byte rom_byte_number |
| 337 * with mask rom_byte_mask */ | |
| 338 if (search_direction == 1) | |
| 339 ROM[rom_byte_number] |= rom_byte_mask; | |
| 340 else | |
| 341 ROM[rom_byte_number] &= ~rom_byte_mask; | |
| 0 | 342 |
| 21 | 343 /* serial number search direction write bit */ |
| 344 OWWriteBit(search_direction); | |
| 0 | 345 |
| 21 | 346 /* increment the byte counter bit_number |
| 347 * and shift the mask rom_byte_mask */ | |
| 348 bit_number++; | |
| 349 rom_byte_mask <<= 1; | |
| 0 | 350 |
| 21 | 351 /* if the mask is 0 then go to new ROM byte rom_byte_number |
| 352 * and reset mask */ | |
| 353 if (rom_byte_mask == 0) { | |
| 354 OWCRC(ROM[rom_byte_number], &crcaccum); /* accumulate the CRC */ | |
| 355 lastcrc8 = crcaccum; | |
| 0 | 356 |
| 21 | 357 rom_byte_number++; |
| 358 rom_byte_mask = 1; | |
| 359 } | |
| 360 } | |
| 361 } while (rom_byte_number < 8); /* loop until through all ROM bytes 0-7 */ | |
| 0 | 362 |
| 21 | 363 /* if the search was successful then */ |
| 364 if (!(bit_number < 65) || lastcrc8) { | |
| 365 if (lastcrc8) { | |
| 12 | 366 #if OW_DEBUG |
| 21 | 367 sprintf_P(errstr, PSTR("Bad CRC (%d)\n\r"), lastcrc8); |
| 368 uart_puts(errstr); | |
| 12 | 369 #endif |
| 21 | 370 next_result = OW_BADCRC; |
| 371 } else { | |
| 372 /* search successful so set LastDiscrepancy,LastDevice,next_result */ | |
| 373 OW_LastDiscrepancy = last_zero; | |
| 374 OW_LastDevice = (OW_LastDiscrepancy == 0); | |
| 0 | 375 #if OW_DEBUG |
| 21 | 376 sprintf_P(errstr, PSTR("Last device = %d\n\r"), OW_LastDevice); |
| 377 uart_puts(errstr); | |
| 0 | 378 #endif |
| 21 | 379 next_result = OW_FOUND; |
| 380 } | |
| 381 } | |
| 382 } | |
| 0 | 383 |
| 21 | 384 /* if no device found then reset counters so next 'next' will be |
| 385 * like a first */ | |
| 386 if (next_result != OW_FOUND || ROM[0] == 0) { | |
| 387 OW_LastDiscrepancy = 0; | |
| 388 OW_LastDevice = 0; | |
| 389 OW_LastFamilyDiscrepancy = 0; | |
| 390 } | |
| 0 | 391 |
| 21 | 392 if (next_result == OW_FOUND && ROM[0] == 0x00) |
| 393 next_result = OW_BADWIRE; | |
| 10 | 394 |
| 21 | 395 return next_result; |
| 0 | 396 |
| 397 } | |
| 398 | |
| 399 uint8_t PROGMEM dscrc_table[] = { | |
| 400 0, 94, 188, 226, 97, 63, 221, 131, 194, 156, 126, 32, 163, 253, 31, 65, | |
| 401 157, 195, 33, 127, 252, 162, 64, 30, 95, 1, 227, 189, 62, 96, 130, 220, | |
| 402 35, 125, 159, 193, 66, 28, 254, 160, 225, 191, 93, 3, 128, 222, 60, 98, | |
| 403 190, 224, 2, 92, 223, 129, 99, 61, 124, 34, 192, 158, 29, 67, 161, 255, | |
| 404 70, 24, 250, 164, 39, 121, 155, 197, 132, 218, 56, 102, 229, 187, 89, 7, | |
| 405 219, 133,103, 57, 186, 228, 6, 88, 25, 71, 165, 251, 120, 38, 196, 154, | |
| 406 101, 59, 217, 135, 4, 90, 184, 230, 167, 249, 27, 69, 198, 152, 122, 36, | |
| 407 248, 166, 68, 26, 153, 199, 37, 123, 58, 100, 134, 216, 91, 5, 231, 185, | |
| 408 140,210, 48, 110, 237, 179, 81, 15, 78, 16, 242, 172, 47, 113,147, 205, | |
| 409 17, 79, 173, 243, 112, 46, 204, 146, 211,141, 111, 49, 178, 236, 14, 80, | |
| 410 175, 241, 19, 77, 206, 144, 114, 44, 109, 51, 209, 143, 12, 82,176, 238, | |
| 411 50, 108, 142, 208, 83, 13, 239, 177, 240, 174, 76, 18, 145, 207, 45, 115, | |
| 412 202, 148, 118, 40, 171, 245, 23, 73, 8, 86, 180, 234, 105, 55, 213, 139, | |
| 413 87, 9, 235, 181, 54, 104, 138, 212, 149, 203, 41, 119, 244, 170, 72, 22, | |
| 414 233, 183, 85, 11, 136, 214, 52, 106, 43, 117, 151, 201, 74, 20, 246, 168, | |
| 415 116, 42, 200, 150, 21, 75, 169, 247, 182, 232, 10, 84, 215, 137, 107, 53 | |
| 416 }; | |
| 417 | |
| 418 void | |
| 419 OWCRC(uint8_t x, uint8_t *crc) { | |
| 420 *crc = pgm_read_byte(&dscrc_table[(*crc) ^ x]); | |
| 421 } |