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annotate 1wire.c @ 29:02b67e09ca12
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author | darius |
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date | Mon, 10 Apr 2006 17:23:03 +0930 |
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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 | |
33 #include <stdio.h> | |
34 #include <avr/io.h> | |
35 #include <avr/pgmspace.h> | |
21 | 36 #include <util/delay.h> |
0 | 37 #include "1wire.h" |
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38 #include "1wire-delay.h" |
0 | 39 |
12 | 40 #if OW_DEBUG |
0 | 41 void uart_putsP(const char *addr); |
42 void uart_puts(const char *addr); | |
43 void uart_getc(); | |
21 | 44 char uart_putc(char c); |
12 | 45 #endif |
0 | 46 |
47 static uint8_t OW_LastDevice = 0; | |
48 static uint8_t OW_LastDiscrepancy = 0; | |
49 static uint8_t OW_LastFamilyDiscrepancy = 0; | |
50 | |
51 static void | |
52 OWdelay(void) { | |
10 | 53 DELAY_I; |
0 | 54 } |
55 | |
56 /*----------------------------------------------------------------------------- | |
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57 * Generate a 1-Wire reset, return 0 if presence pulse was found, 1 if it |
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58 * wasn't, or 2 if the line appears to be being held low. |
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59 * |
0 | 60 * (NOTE: Does not handle alarm presence from DS2404/DS1994) |
61 */ | |
12 | 62 uint8_t |
0 | 63 OWTouchReset(void) { |
10 | 64 DELAY_G; |
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65 |
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66 if (!(OWIREINPORT & _BV(OWIREINPIN))) |
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67 return 2; |
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68 |
10 | 69 OWIREOUTPORT &= ~(_BV(OWIREOUTPIN)); |
70 OWIREDDR |= _BV(OWIREOUTPIN); | |
71 DELAY_H; | |
72 OWIREDDR &= ~(_BV(OWIREOUTPIN)); | |
73 DELAY_I; | |
0 | 74 |
10 | 75 return(OWIREINPORT & _BV(OWIREINPIN) ? 1 : 0); |
0 | 76 } |
77 | |
78 /*----------------------------------------------------------------------------- | |
79 * Send a 1-wire write bit. | |
80 */ | |
81 void | |
12 | 82 OWWriteBit(uint8_t bit) { |
0 | 83 OWdelay(); |
84 if (bit) { | |
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85 OWIREOUTPORT &= ~(_BV(OWIREOUTPIN)); |
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86 OWIREDDR |= _BV(OWIREOUTPIN); |
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87 DELAY_A; |
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88 OWIREDDR &= ~(_BV(OWIREOUTPIN)); |
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89 DELAY_B; |
0 | 90 } else { |
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91 OWIREOUTPORT &= ~(_BV(OWIREOUTPIN)); |
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92 OWIREDDR |= _BV(OWIREOUTPIN); |
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93 DELAY_C; |
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94 OWIREDDR &= ~(_BV(OWIREOUTPIN)); |
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95 DELAY_D; |
0 | 96 } |
97 } | |
98 | |
99 /*----------------------------------------------------------------------------- | |
100 * Read a bit from the 1-wire bus and return it. | |
101 */ | |
12 | 102 uint8_t |
0 | 103 OWReadBit(void) { |
104 OWdelay(); | |
105 | |
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106 OWIREOUTPORT &= ~(_BV(OWIREOUTPIN)); |
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107 OWIREDDR |= _BV(OWIREOUTPIN); |
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108 DELAY_A; |
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109 OWIREDDR &= ~(_BV(OWIREOUTPIN)); |
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110 DELAY_E; |
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111 return(OWIREINPORT & _BV(OWIREINPIN) ? 1 : 0); |
0 | 112 } |
113 | |
114 /*----------------------------------------------------------------------------- | |
115 * Write a byte to the 1-wire bus | |
116 */ | |
117 void | |
118 OWWriteByte(uint8_t data) { | |
12 | 119 uint8_t i; |
0 | 120 |
121 /* Send LSB first */ | |
122 for (i = 0; i < 8; i++) { | |
123 OWWriteBit(data & 0x01); | |
124 data >>= 1; | |
125 } | |
126 } | |
127 | |
128 /*----------------------------------------------------------------------------- | |
129 * Read a byte from the 1-wire bus | |
130 */ | |
12 | 131 uint8_t |
0 | 132 OWReadByte(void) { |
133 int i, result = 0; | |
134 | |
135 for (i = 0; i < 8; i++) { | |
136 result >>= 1; | |
137 if (OWReadBit()) | |
138 result |= 0x80; | |
139 } | |
140 return(result); | |
141 } | |
142 | |
143 /*----------------------------------------------------------------------------- | |
144 * Write a 1-wire data byte and return the sampled result. | |
145 */ | |
12 | 146 uint8_t |
0 | 147 OWTouchByte(uint8_t data) { |
12 | 148 uint8_t i, result = 0; |
0 | 149 |
150 for (i = 0; i < 8; i++) { | |
151 result >>= 1; | |
152 | |
153 /* If sending a 1 then read a bit, otherwise write a 0 */ | |
154 if (data & 0x01) { | |
155 if (OWReadBit()) | |
156 result |= 0x80; | |
157 } else | |
158 OWWriteBit(0); | |
159 | |
160 data >>= 1; | |
161 } | |
162 | |
163 return(result); | |
164 } | |
165 | |
166 /*----------------------------------------------------------------------------- | |
167 * Write a block of bytes to the 1-wire bus and return the sampled result in | |
168 * the same buffer | |
169 */ | |
170 void | |
171 OWBlock(uint8_t *data, int len) { | |
172 int i; | |
173 | |
174 for (i = 0; i < len; i++) | |
175 data[i] = OWTouchByte(data[i]); | |
176 } | |
177 | |
178 | |
179 /*----------------------------------------------------------------------------- | |
180 * Send a 1 wire command to a device, or all if no ROM ID provided | |
181 */ | |
182 void | |
183 OWSendCmd(uint8_t *ROM, uint8_t cmd) { | |
12 | 184 uint8_t i; |
0 | 185 |
186 OWTouchReset(); | |
187 | |
188 if (ROM == NULL) | |
189 OWWriteByte(OW_SKIP_ROM_CMD); | |
190 else { | |
191 OWWriteByte(OW_MATCH_ROM_CMD); | |
192 for (i = 0; i < 8; i++) | |
193 OWWriteByte(ROM[i]); | |
194 } | |
195 | |
196 OWWriteByte(cmd); | |
197 } | |
198 | |
199 /*----------------------------------------------------------------------------- | |
200 * Search algorithm from App note 187 (and 162) | |
201 * | |
10 | 202 * OWFirst/OWNext return.. |
203 * 1 when something is found, | |
204 * 0 no more modules | |
16 | 205 * -1 if no presence pulse, |
10 | 206 * -2 if bad CRC, |
207 * -3 if bad wiring. | |
0 | 208 */ |
12 | 209 uint8_t |
0 | 210 OWFirst(uint8_t *ROM, uint8_t do_reset, uint8_t alarm_only) { |
211 /* Reset state */ | |
212 OW_LastDiscrepancy = 0; | |
213 OW_LastDevice = 0; | |
214 OW_LastFamilyDiscrepancy = 0; | |
215 | |
216 /* Go looking */ | |
217 return (OWNext(ROM, do_reset, alarm_only)); | |
218 } | |
219 | |
220 /* Returns 1 when something is found, 0 if nothing left */ | |
12 | 221 uint8_t |
0 | 222 OWNext(uint8_t *ROM, uint8_t do_reset, uint8_t alarm_only) { |
223 uint8_t bit_test, search_direction, bit_number; | |
10 | 224 uint8_t last_zero, rom_byte_number, rom_byte_mask; |
0 | 225 uint8_t lastcrc8, crcaccum; |
12 | 226 int8_t next_result; |
0 | 227 |
228 /* Init for search */ | |
21 | 229 bit_number = 1; |
230 last_zero = 0; | |
231 rom_byte_number = 0; | |
232 rom_byte_mask = 1; | |
233 next_result = OW_NOMODULES; | |
234 lastcrc8 = 0; | |
235 crcaccum = 0; | |
0 | 236 |
21 | 237 /* if the last call was not the last one */ |
238 if (!OW_LastDevice) { | |
239 /* check if reset first is requested */ | |
240 if (do_reset) { | |
241 /* reset the 1-wire | |
242 * if there are no parts on 1-wire, return 0 */ | |
0 | 243 #if OW_DEBUG |
21 | 244 uart_putsP(PSTR("Resetting\n\r")); |
0 | 245 #endif |
22
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246 switch (OWTouchReset()) { |
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247 case 0: |
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248 break; |
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249 |
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250 case 1: |
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251 /* reset the search */ |
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252 OW_LastDiscrepancy = 0; |
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253 OW_LastFamilyDiscrepancy = 0; |
0 | 254 #if OW_DEBUG |
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255 uart_putsP(PSTR("No devices on bus\n\r")); |
0 | 256 #endif |
22
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257 return OW_NOPRESENCE; |
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258 break; |
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259 |
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260 case 2: |
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261 /* reset the search */ |
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262 OW_LastDiscrepancy = 0; |
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263 OW_LastFamilyDiscrepancy = 0; |
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264 #if OW_DEBUG |
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265 uart_putsP(PSTR("Bus appears to be being held low\n\r")); |
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266 #endif |
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267 return OW_BADWIRE; |
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268 break; |
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269 |
21 | 270 } |
271 } | |
0 | 272 |
21 | 273 /* If finding alarming devices issue a different command */ |
274 if (alarm_only) | |
275 OWWriteByte(OW_SEARCH_ALRM_CMD); /* issue the alarming search command */ | |
276 else | |
277 OWWriteByte(OW_SEARCH_ROM_CMD); /* issue the search command */ | |
0 | 278 |
21 | 279 /* pause before beginning the search */ |
280 OWdelay(); | |
281 OWdelay(); | |
282 OWdelay(); | |
0 | 283 |
21 | 284 /* loop to do the search */ |
285 do { | |
286 /* read a bit and its compliment */ | |
287 bit_test = OWReadBit() << 1; | |
288 bit_test |= OWReadBit(); | |
0 | 289 |
290 #if OW_DEBUG | |
21 | 291 sprintf_P(errstr, PSTR("bit_test = %d\n\r"), bit_test); |
292 uart_puts(errstr); | |
0 | 293 #endif |
294 | |
21 | 295 /* check for no devices on 1-wire */ |
296 if (bit_test == 3) { | |
10 | 297 #if OW_DEBUG |
21 | 298 sprintf_P(errstr, PSTR("bit_test = %d\n\r"), bit_test); |
299 uart_puts(errstr); | |
10 | 300 #endif |
21 | 301 return(OW_BADWIRE); |
302 } | |
303 else { | |
304 /* all devices coupled have 0 or 1 */ | |
305 if (bit_test > 0) | |
306 search_direction = !(bit_test & 0x01); /* bit write value for search */ | |
307 else { | |
308 /* if this discrepancy is before the Last Discrepancy | |
309 * on a previous OWNext then pick the same as last time */ | |
310 if (bit_number < OW_LastDiscrepancy) | |
311 search_direction = ((ROM[rom_byte_number] & rom_byte_mask) > 0); | |
312 else | |
313 /* if equal to last pick 1, if not then pick 0 */ | |
314 search_direction = (bit_number == OW_LastDiscrepancy); | |
0 | 315 |
21 | 316 /* if 0 was picked then record its position in LastZero */ |
317 if (search_direction == 0) { | |
318 last_zero = bit_number; | |
0 | 319 |
21 | 320 /* check for Last discrepancy in family */ |
321 if (last_zero < 9) | |
322 OW_LastFamilyDiscrepancy = last_zero; | |
323 } | |
324 } | |
0 | 325 |
21 | 326 /* set or clear the bit in the ROM byte rom_byte_number |
327 * with mask rom_byte_mask */ | |
328 if (search_direction == 1) | |
329 ROM[rom_byte_number] |= rom_byte_mask; | |
330 else | |
331 ROM[rom_byte_number] &= ~rom_byte_mask; | |
0 | 332 |
21 | 333 /* serial number search direction write bit */ |
334 OWWriteBit(search_direction); | |
0 | 335 |
21 | 336 /* increment the byte counter bit_number |
337 * and shift the mask rom_byte_mask */ | |
338 bit_number++; | |
339 rom_byte_mask <<= 1; | |
0 | 340 |
21 | 341 /* if the mask is 0 then go to new ROM byte rom_byte_number |
342 * and reset mask */ | |
343 if (rom_byte_mask == 0) { | |
344 OWCRC(ROM[rom_byte_number], &crcaccum); /* accumulate the CRC */ | |
345 lastcrc8 = crcaccum; | |
0 | 346 |
21 | 347 rom_byte_number++; |
348 rom_byte_mask = 1; | |
349 } | |
350 } | |
351 } while (rom_byte_number < 8); /* loop until through all ROM bytes 0-7 */ | |
0 | 352 |
21 | 353 /* if the search was successful then */ |
354 if (!(bit_number < 65) || lastcrc8) { | |
355 if (lastcrc8) { | |
12 | 356 #if OW_DEBUG |
21 | 357 sprintf_P(errstr, PSTR("Bad CRC (%d)\n\r"), lastcrc8); |
358 uart_puts(errstr); | |
12 | 359 #endif |
21 | 360 next_result = OW_BADCRC; |
361 } else { | |
362 /* search successful so set LastDiscrepancy,LastDevice,next_result */ | |
363 OW_LastDiscrepancy = last_zero; | |
364 OW_LastDevice = (OW_LastDiscrepancy == 0); | |
0 | 365 #if OW_DEBUG |
21 | 366 sprintf_P(errstr, PSTR("Last device = %d\n\r"), OW_LastDevice); |
367 uart_puts(errstr); | |
0 | 368 #endif |
21 | 369 next_result = OW_FOUND; |
370 } | |
371 } | |
372 } | |
0 | 373 |
21 | 374 /* if no device found then reset counters so next 'next' will be |
375 * like a first */ | |
376 if (next_result != OW_FOUND || ROM[0] == 0) { | |
377 OW_LastDiscrepancy = 0; | |
378 OW_LastDevice = 0; | |
379 OW_LastFamilyDiscrepancy = 0; | |
380 } | |
0 | 381 |
21 | 382 if (next_result == OW_FOUND && ROM[0] == 0x00) |
383 next_result = OW_BADWIRE; | |
10 | 384 |
21 | 385 return next_result; |
0 | 386 |
387 } | |
388 | |
389 uint8_t PROGMEM dscrc_table[] = { | |
390 0, 94, 188, 226, 97, 63, 221, 131, 194, 156, 126, 32, 163, 253, 31, 65, | |
391 157, 195, 33, 127, 252, 162, 64, 30, 95, 1, 227, 189, 62, 96, 130, 220, | |
392 35, 125, 159, 193, 66, 28, 254, 160, 225, 191, 93, 3, 128, 222, 60, 98, | |
393 190, 224, 2, 92, 223, 129, 99, 61, 124, 34, 192, 158, 29, 67, 161, 255, | |
394 70, 24, 250, 164, 39, 121, 155, 197, 132, 218, 56, 102, 229, 187, 89, 7, | |
395 219, 133,103, 57, 186, 228, 6, 88, 25, 71, 165, 251, 120, 38, 196, 154, | |
396 101, 59, 217, 135, 4, 90, 184, 230, 167, 249, 27, 69, 198, 152, 122, 36, | |
397 248, 166, 68, 26, 153, 199, 37, 123, 58, 100, 134, 216, 91, 5, 231, 185, | |
398 140,210, 48, 110, 237, 179, 81, 15, 78, 16, 242, 172, 47, 113,147, 205, | |
399 17, 79, 173, 243, 112, 46, 204, 146, 211,141, 111, 49, 178, 236, 14, 80, | |
400 175, 241, 19, 77, 206, 144, 114, 44, 109, 51, 209, 143, 12, 82,176, 238, | |
401 50, 108, 142, 208, 83, 13, 239, 177, 240, 174, 76, 18, 145, 207, 45, 115, | |
402 202, 148, 118, 40, 171, 245, 23, 73, 8, 86, 180, 234, 105, 55, 213, 139, | |
403 87, 9, 235, 181, 54, 104, 138, 212, 149, 203, 41, 119, 244, 170, 72, 22, | |
404 233, 183, 85, 11, 136, 214, 52, 106, 43, 117, 151, 201, 74, 20, 246, 168, | |
405 116, 42, 200, 150, 21, 75, 169, 247, 182, 232, 10, 84, 215, 137, 107, 53 | |
406 }; | |
407 | |
408 void | |
409 OWCRC(uint8_t x, uint8_t *crc) { | |
410 *crc = pgm_read_byte(&dscrc_table[(*crc) ^ x]); | |
411 } |