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comparison 1wire.c @ 22:bd792ebf813d

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Report the bus being held low back to the caller from OWFirst/Next.
author darius
date Mon, 12 Dec 2005 23:27:40 +1030
parents e82d15fa9a1a
children 02b67e09ca12
comparison
equal deleted inserted replaced
21:e82d15fa9a1a 22:bd792ebf813d
52 OWdelay(void) { 52 OWdelay(void) {
53 DELAY_I; 53 DELAY_I;
54 } 54 }
55 55
56 /*----------------------------------------------------------------------------- 56 /*-----------------------------------------------------------------------------
57 * Generate a 1-Wire reset, return 0 if presence pulse was found, 57 * Generate a 1-Wire reset, return 0 if presence pulse was found, 1 if it
58 * return 1 otherwise. 58 * wasn't, or 2 if the line appears to be being held low.
59 *
59 * 60 *
60 * (NOTE: Does not handle alarm presence from DS2404/DS1994) 61 * (NOTE: Does not handle alarm presence from DS2404/DS1994)
61 */ 62 */
62 uint8_t 63 uint8_t
63 OWTouchReset(void) { 64 OWTouchReset(void) {
64 DELAY_G; 65 DELAY_G;
66
67 if (!(OWIREINPORT & _BV(OWIREINPIN)))
68 return 2;
69
65 OWIREOUTPORT &= ~(_BV(OWIREOUTPIN)); 70 OWIREOUTPORT &= ~(_BV(OWIREOUTPIN));
66 OWIREDDR |= _BV(OWIREOUTPIN); 71 OWIREDDR |= _BV(OWIREOUTPIN);
67 DELAY_H; 72 DELAY_H;
68 OWIREDDR &= ~(_BV(OWIREOUTPIN)); 73 OWIREDDR &= ~(_BV(OWIREOUTPIN));
69 DELAY_I; 74 DELAY_I;
237 /* reset the 1-wire 242 /* reset the 1-wire
238 * if there are no parts on 1-wire, return 0 */ 243 * if there are no parts on 1-wire, return 0 */
239 #if OW_DEBUG 244 #if OW_DEBUG
240 uart_putsP(PSTR("Resetting\n\r")); 245 uart_putsP(PSTR("Resetting\n\r"));
241 #endif 246 #endif
242 if (OWTouchReset()) { 247 switch (OWTouchReset()) {
243 /* reset the search */ 248 case 0:
244 OW_LastDiscrepancy = 0; 249 break;
245 OW_LastFamilyDiscrepancy = 0; 250
246 #if OW_DEBUG 251 case 1:
247 uart_putsP(PSTR("No devices on bus\n\r")); 252 /* reset the search */
248 #endif 253 OW_LastDiscrepancy = 0;
249 return OW_NOPRESENCE; 254 OW_LastFamilyDiscrepancy = 0;
255 #if OW_DEBUG
256 uart_putsP(PSTR("No devices on bus\n\r"));
257 #endif
258 return OW_NOPRESENCE;
259 break;
260
261 case 2:
262 /* reset the search */
263 OW_LastDiscrepancy = 0;
264 OW_LastFamilyDiscrepancy = 0;
265 #if OW_DEBUG
266 uart_putsP(PSTR("Bus appears to be being held low\n\r"));
267 #endif
268 return OW_BADWIRE;
269 break;
270
250 } 271 }
251 } 272 }
252 273
253 /* If finding alarming devices issue a different command */ 274 /* If finding alarming devices issue a different command */
254 if (alarm_only) 275 if (alarm_only)