Mercurial > ~darius > hgwebdir.cgi > avr-lib

comparison ds1307.c @ 8:119688bb743f

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Don't spin forever waiting for the TWI hardware to do something. I _think_ this will help the case where I find the micro is hanging but I haven't seen an error from it yet.
author darius@dons.net.au
date Fri, 01 May 2009 15:21:31 +0930
parents 3da232f97e81
children b5e4591b6570
comparison
equal deleted inserted replaced
7:d111f64eb619 8:119688bb743f
36 36
37 #include "ds1307.h" 37 #include "ds1307.h"
38 38
39 // #define TWDEBUG 39 // #define TWDEBUG
40 40
41 /* Helper code to wait for the TWCR to do something */
42 #define WAITFORTWINT() do { \
43 uint8_t i; \
44 for (i = 0; i < 255 && (TWCR & _BV(TWINT)) == 0; i++) \
45 _delay_ms(1); \
46 if (i == 255) \
47 return(IIC_NORESP); \
48 } while (0)
49
50
41 /* 51 /*
42 * ds1307_init 52 * ds1307_init
43 * 53 *
44 * Setup TWI interface 54 * Setup TWI interface
45 * 55 *
85 95
86 /* Generate START */ 96 /* Generate START */
87 TWCR = _BV(TWINT) | _BV(TWSTA) | _BV(TWEN); 97 TWCR = _BV(TWINT) | _BV(TWSTA) | _BV(TWEN);
88 98
89 /* Spin waiting for START to be generated */ 99 /* Spin waiting for START to be generated */
90 while ((TWCR & _BV(TWINT)) == 0) 100 WAITFORTWINT();
91 ; 101
92 switch (twst = TW_STATUS) { 102 switch (twst = TW_STATUS) {
93 case TW_REP_START: /* OK but shouldn't happen */ 103 case TW_REP_START: /* OK but shouldn't happen */
94 case TW_START: 104 case TW_START:
95 break; 105 break;
96 106
108 /* Send SLA+W */ 118 /* Send SLA+W */
109 TWDR = sla | TW_WRITE; 119 TWDR = sla | TW_WRITE;
110 TWCR = _BV(TWINT) | _BV(TWEN); 120 TWCR = _BV(TWINT) | _BV(TWEN);
111 121
112 /* Spin waiting for a response to be generated */ 122 /* Spin waiting for a response to be generated */
113 while ((TWCR & _BV(TWINT)) == 0) 123 WAITFORTWINT();
114 ;
115 124
116 #ifdef TWDEBUG 125 #ifdef TWDEBUG
117 printf_P(PSTR("Sent SLA+W\r\n")); 126 printf_P(PSTR("Sent SLA+W\r\n"));
118 #endif 127 #endif
119 switch (twst = TW_STATUS) { 128 switch (twst = TW_STATUS) {
137 /* Send address */ 146 /* Send address */
138 TWDR = adr; 147 TWDR = adr;
139 TWCR = _BV(TWINT) | _BV(TWEN); 148 TWCR = _BV(TWINT) | _BV(TWEN);
140 149
141 /* Spin waiting for a response to be generated */ 150 /* Spin waiting for a response to be generated */
142 while ((TWCR & _BV(TWINT)) == 0) 151 WAITFORTWINT();
143 ; 152
144 #ifdef TWDEBUG 153 #ifdef TWDEBUG
145 printf_P(PSTR("Sent address\r\n")); 154 printf_P(PSTR("Sent address\r\n"));
146 #endif 155 #endif
147 switch ((twst = TW_STATUS)) { 156 switch ((twst = TW_STATUS)) {
148 case TW_MT_DATA_ACK: 157 case TW_MT_DATA_ACK:
162 return IIC_UNKNOWN; 171 return IIC_UNKNOWN;
163 } 172 }
164 173
165 /* Master receive cycle */ 174 /* Master receive cycle */
166 TWCR = _BV(TWINT) | _BV(TWSTA) | _BV(TWEN); 175 TWCR = _BV(TWINT) | _BV(TWSTA) | _BV(TWEN);
167 while ((TWCR & _BV(TWINT)) == 0) /* wait for transmission */ 176
168 ; 177 /* wait for transmission */
178 WAITFORTWINT();
169 179
170 #ifdef TWDEBUG 180 #ifdef TWDEBUG
171 printf_P(PSTR("Sent START\r\n")); 181 printf_P(PSTR("Sent START\r\n"));
172 #endif 182 #endif
173 switch ((twst = TW_STATUS)) { 183 switch ((twst = TW_STATUS)) {
187 /* send SLA+R */ 197 /* send SLA+R */
188 TWDR = sla | TW_READ; 198 TWDR = sla | TW_READ;
189 TWCR = _BV(TWINT) | _BV(TWEN); /* clear interrupt to start transmission */ 199 TWCR = _BV(TWINT) | _BV(TWEN); /* clear interrupt to start transmission */
190 200
191 /* Spin waiting for a response to be generated */ 201 /* Spin waiting for a response to be generated */
192 while ((TWCR & _BV(TWINT)) == 0) 202 WAITFORTWINT();
193 ; 203
194 #ifdef TWDEBUG 204 #ifdef TWDEBUG
195 printf_P(PSTR("Sent SLA+R\r\n")); 205 printf_P(PSTR("Sent SLA+R\r\n"));
196 #endif 206 #endif
197 switch ((twst = TW_STATUS)) { 207 switch ((twst = TW_STATUS)) {
198 case TW_MR_SLA_ACK: 208 case TW_MR_SLA_ACK:
218 /* Send NAK on last byte */ 228 /* Send NAK on last byte */
219 if (len == 1) 229 if (len == 1)
220 twcr = _BV(TWINT) | _BV(TWEN); 230 twcr = _BV(TWINT) | _BV(TWEN);
221 TWCR = twcr; /* clear int to start transmission */ 231 TWCR = twcr; /* clear int to start transmission */
222 /* Spin waiting for a response to be generated */ 232 /* Spin waiting for a response to be generated */
223 while ((TWCR & _BV(TWINT)) == 0) 233 WAITFORTWINT();
224 ; 234
225 #ifdef TWDEBUG 235 #ifdef TWDEBUG
226 printf_P(PSTR("Data request done\r\n")); 236 printf_P(PSTR("Data request done\r\n"));
227 #endif 237 #endif
228 switch ((twst = TW_STATUS)) { 238 switch ((twst = TW_STATUS)) {
229 case TW_MR_DATA_NACK: 239 case TW_MR_DATA_NACK:
270 280
271 /* Generate START */ 281 /* Generate START */
272 TWCR = _BV(TWINT) | _BV(TWSTA) | _BV(TWEN); 282 TWCR = _BV(TWINT) | _BV(TWSTA) | _BV(TWEN);
273 283
274 /* Spin waiting for START to be generated */ 284 /* Spin waiting for START to be generated */
275 while ((TWCR & _BV(TWINT)) == 0) 285 WAITFORTWINT();
276 ; 286
277 switch (twst = TW_STATUS) { 287 switch (twst = TW_STATUS) {
278 case TW_REP_START: /* OK but shouldn't happen */ 288 case TW_REP_START: /* OK but shouldn't happen */
279 case TW_START: 289 case TW_START:
280 break; 290 break;
281 291
294 /* Send SLA+W */ 304 /* Send SLA+W */
295 TWDR = sla | TW_WRITE; 305 TWDR = sla | TW_WRITE;
296 TWCR = _BV(TWINT) | _BV(TWEN); 306 TWCR = _BV(TWINT) | _BV(TWEN);
297 307
298 /* Spin waiting for a response to be generated */ 308 /* Spin waiting for a response to be generated */
299 while ((TWCR & _BV(TWINT)) == 0) 309 WAITFORTWINT();
300 ;
301 310
302 #ifdef TWDEBUG 311 #ifdef TWDEBUG
303 printf_P(PSTR("Sent SLA+W\r\n")); 312 printf_P(PSTR("Sent SLA+W\r\n"));
304 #endif 313 #endif
305 switch (twst = TW_STATUS) { 314 switch (twst = TW_STATUS) {
323 /* Send address */ 332 /* Send address */
324 TWDR = adr; 333 TWDR = adr;
325 TWCR = _BV(TWINT) | _BV(TWEN); 334 TWCR = _BV(TWINT) | _BV(TWEN);
326 335
327 /* Spin waiting for a response to be generated */ 336 /* Spin waiting for a response to be generated */
328 while ((TWCR & _BV(TWINT)) == 0) 337 WAITFORTWINT();
329 ; 338
330 #ifdef TWDEBUG 339 #ifdef TWDEBUG
331 printf_P(PSTR("Sent address\r\n")); 340 printf_P(PSTR("Sent address\r\n"));
332 #endif 341 #endif
333 switch ((twst = TW_STATUS)) { 342 switch ((twst = TW_STATUS)) {
334 case TW_MT_DATA_ACK: 343 case TW_MT_DATA_ACK:
352 for (; len > 0; len--) { 361 for (; len > 0; len--) {
353 TWDR = *data++; 362 TWDR = *data++;
354 TWCR = _BV(TWINT) | _BV(TWEN); 363 TWCR = _BV(TWINT) | _BV(TWEN);
355 364
356 /* Spin waiting for a response to be generated */ 365 /* Spin waiting for a response to be generated */
357 while ((TWCR & _BV(TWINT)) == 0) 366 WAITFORTWINT();
358 ; 367
359 #ifdef TWDEBUG 368 #ifdef TWDEBUG
360 printf_P(PSTR("Data sent\r\n")); 369 printf_P(PSTR("Data sent\r\n"));
361 #endif 370 #endif
362 switch ((twst = TW_STATUS)) { 371 switch ((twst = TW_STATUS)) {
363 case TW_MT_DATA_NACK: 372 case TW_MT_DATA_NACK: