1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
|
#include "config.h"
#include "i2c.h"
#include <util/delay.h>
#include "io.h"
#include "debug.h"
/*
- Reset bus on failure (lack of ACK, etc)
- Clock stretching
- In pull-up mode, much code was commented out to ever avoid driving the bus (for a fleeting moment) as this was visible on the scope as short peaks (instead the line will briefly go Hi Z).
*/
volatile bool _i2c_disable_ack_check = false;
// FIXME: Follow magic numbers should be in a struct that is passed into each function
#define I2C_DEFAULT_RETRY_DELAY 1 // us MAGIC
#define I2C_DEFAULT_MAX_ACK_RETRIES 10 // * I2C_DEFAULT_RETRY_DELAY us
#define I2C_DEFAULT_BUS_WAIT 10 // us MAGIC
#define I2C_DEFAULT_MAX_BUS_RETRIES 10
#define I2C_DEFAULT_SCL_LOW_PERIOD 2 // 1.3 us
#define I2C_DEFAULT_SCL_HIGH_PERIOD 1 // 0.6 us
#define I2C_DEFAULT_BUS_FREE_TIME 2 // 1.3 us
#define I2C_DEFAULT_STOP_TIME 1 // 0.6 us
#define I2C_DELAY _delay_us // _delay_ms
static bool _i2c_start_ex(io_pin_t sda, io_pin_t scl, bool pull_up)
{
// Assumes: SDA/SCL are both inputs
uint8_t retries = I2C_DEFAULT_MAX_BUS_RETRIES;
while ((io_test_pin(sda) == false) || (io_test_pin(scl) == false))
{
I2C_DELAY(I2C_DEFAULT_BUS_WAIT);
if (retries-- == 0)
{
debug_log("I2C:S1");
return false;
}
}
// START condition
// if (pull_up == false)
io_clear_pin(sda); // Set LOW before switching to output
io_output_pin(sda);
// if (pull_up)
// io_clear_pin(sda);
I2C_DELAY(I2C_DEFAULT_SCL_LOW_PERIOD); // Thd, sta
retries = I2C_DEFAULT_MAX_BUS_RETRIES;
while (io_test_pin(scl) == false) // SCL should remain high
{
I2C_DELAY(I2C_DEFAULT_BUS_WAIT);
if (retries-- == 0)
{
io_input_pin(sda);
debug_log_ex("I2C:S2", false);
debug_log_hex(scl);
return false;
}
}
// if (pull_up == false)
io_clear_pin(scl);
io_output_pin(scl);
// if (pull_up)
// io_clear_pin(scl);
I2C_DELAY(I2C_DEFAULT_SCL_LOW_PERIOD / 2); // MAGIC
return true;
}
static bool _i2c_stop_ex(io_pin_t sda, io_pin_t scl, bool pull_up)
{
// Assumes:
// SCL is output & LOW
// SDA is input (Hi-Z, or pull-up enabled)
// Assuming pull-up already enabled
//if (pull_up)
// io_set_pin(sda);
bool result = true;
// SDA should be HIGH after ACK has been clocked away
// bool skip_drive = false;
uint8_t retries = 0;
while (io_test_pin(sda) == false)
{
if (retries == I2C_DEFAULT_MAX_ACK_RETRIES)
{
debug_log_ex("I2C:STP ", false);
debug_log_hex(sda);
debug_blink_rev(4);
// skip_drive = true;
result = false;
break; // SDA is being held low?!
}
++retries;
I2C_DELAY(I2C_DEFAULT_RETRY_DELAY);
}
// STOP condition
// if ((pull_up == false) || (skip_drive))
io_clear_pin(sda); // Don't tri-state if internal pull-up is used
// //else
// // Pin will now be driven, but having checked SDA is HIGH above means slave's SDA should be Open Collector (i.e. it won't blow up)
io_output_pin(sda); // Drive LOW
// if (pull_up)
// io_clear_pin(sda);
///////////////////////////////////
// if (pull_up)
// io_set_pin(scl); // Don't tri-state if internal pull-up is used. Line will be driven, but assuming this is the only master on the clock line (i.e. no one else will pull it low).
io_input_pin(scl);
if (pull_up)
io_set_pin(scl);
I2C_DELAY(I2C_DEFAULT_STOP_TIME);
///////////////////////////////////
// if ((pull_up) && (skip_drive == false))
// io_set_pin(sda); // Don't tri-state if internal pull-up is used
io_input_pin(sda);
// if ((pull_up) && (skip_drive))
io_set_pin(sda);
I2C_DELAY(I2C_DEFAULT_BUS_FREE_TIME);
return result;
}
/*
static void _i2c_stop(io_pin_t sda, io_pin_t scl)
{
_i2c_stop_ex(sda, scl, false);
}
*//*
static void _i2c_abort_safe_ex(io_pin_t pin, bool pull_up)
{
if (io_is_output(pin))
{
if (io_is_pin_set(pin)) // This is bad - hope no slave is pulling down the line
{
io_input_pin(pin); // Pull-up already enabled
if (pull_up == false)
io_clear_pin(pin); // Doing this after changing direction ensures the line is not brought down
}
else // Currently pulling line down
{
io_input_pin(pin); // Hi-Z
if (pull_up) // There will be a moment where the line will float (better than driving the line though...)
{
io_set_pin(pin);
}
}
}
else // Already an input
{
if (pull_up)
{
io_set_pin(pin); // Enable pull-ups
}
else
{
io_clear_pin(pin); // Disable pull-ups
}
}
// Normally: pin will be Hi-Z input
// With internal pull-up: pin will be input with pull-up enabled
}
*/
static void _i2c_abort_safe(io_pin_t pin, bool pull_up)
{
if (pull_up == false)
io_clear_pin(pin); // Should never be output/HIGH, could be input/<was outputting HIGH> so disable pull-ups
io_input_pin(pin);
if (pull_up)
io_set_pin(pin); // Enable pull-up
}
static void _i2c_abort_ex(io_pin_t sda, io_pin_t scl, bool pull_up)
{
/* if (pull_up == false)
{
io_clear_pin(sda);
io_clear_pin(scl);
}
io_input_pin(scl);
io_input_pin(sda);
if (pull_up)
{
io_set_pin(sda);
io_set_pin(scl);
}
*/
_i2c_abort_safe(scl, pull_up);
_i2c_abort_safe(sda, pull_up);
//_i2c_abort_safe_ex(scl, pull_up);
//_i2c_abort_safe_ex(sda, pull_up);
}
/*
static void _i2c_abort(io_pin_t sda, io_pin_t scl)
{
_i2c_abort_ex(sda, scl, false);
}
*/
static bool _i2c_write_byte_ex(io_pin_t sda, io_pin_t scl, uint8_t value, bool pull_up)
{
// Assumes:
// SDA output is LOW
// SCL output is LOW
for (uint8_t i = 0; i < 8; ++i)
{
bool b = ((value & (0x01 << (7 - i))) != 0x00); // MSB first
if (b)
{
if (pull_up)
{
// io_set_pin(sda); // This is bad (will drive line for a moment), but more stable than letting line float
io_input_pin(sda);
io_set_pin(sda);
}
else
io_input_pin(sda); // Release HIGH
if (io_test_pin(sda) == false)
{
debug_log("I2C:WR ");
debug_log_hex(sda);
debug_blink_rev(1);
return false;
}
}
else
{
if (pull_up)
{
// if (io_is_output(sda))
io_clear_pin(sda);
// else
// {
io_output_pin(sda); // [This is bad (will drive line for a moment), but more stable than letting line float]
// io_clear_pin(sda);
// }
}
else
{
io_enable_pin(sda, false);
io_output_pin(sda); // Drive LOW
}
}
///////////////////////////////
io_input_pin(scl); // Release HIGH
if (pull_up)
io_set_pin(scl);
I2C_DELAY(I2C_DEFAULT_SCL_HIGH_PERIOD);
#ifdef I2C_ALLOW_CLOCK_STRETCH
uint8_t retries = I2C_DEFAULT_MAX_BUS_RETRIES;
while (io_test_pin(scl) == false) // Clock stretch requested?
{
I2C_DELAY(I2C_DEFAULT_BUS_WAIT);
if (--retries == 0)
{
io_input_pin(sda); // Release HIGH
if (pull_up)
io_set_pin(sda);
debug_log_ex("I2C:STRTCH ", false);
debug_log_hex(scl);
debug_blink_rev(2);
return false;
}
}
#endif // I2C_ALLOW_CLOCK_STRETCH
if (pull_up)
io_clear_pin(scl);
io_output_pin(scl); // Drive LOW
I2C_DELAY(I2C_DEFAULT_SCL_LOW_PERIOD);
}
io_input_pin(sda); // Release HIGH
if (pull_up)
io_set_pin(sda); // Assuming letting line float won't confuse slave when pulling line LOW for ACK
I2C_DELAY(I2C_DEFAULT_SCL_HIGH_PERIOD);
uint8_t retries = 0;
while ((_i2c_disable_ack_check == false) && (io_test_pin(sda)))
{
if (retries == I2C_DEFAULT_MAX_ACK_RETRIES)
{
debug_log_ex("I2C:ACK ", false);
debug_log_hex_ex(sda, false);
debug_log_hex(value);
debug_blink_rev(3);
return false; // Will abort and not release bus - done by caller
}
++retries;
I2C_DELAY(I2C_DEFAULT_RETRY_DELAY);
}
// Clock away acknowledge
// if (pull_up)
// io_set_pin(scl);
io_input_pin(scl); // Release HIGH
if (pull_up)
io_set_pin(scl);
I2C_DELAY(I2C_DEFAULT_SCL_HIGH_PERIOD);
if (pull_up)
io_clear_pin(scl);
io_output_pin(scl); // Drive LOW
// if (pull_up)
// io_clear_pin(scl);
I2C_DELAY(I2C_DEFAULT_SCL_LOW_PERIOD);
return true;
}
static bool _i2c_read_byte_ex(io_pin_t sda, io_pin_t scl, uint8_t* value, bool pull_up)
{
// Assumes:
// SDA output is LOW
// SCL output is LOW
io_input_pin(sda);
if (pull_up)
io_set_pin(sda); // OK to leave line floating for a moment (better not to drive as slave will be pulling it to ground)
(*value) = 0x00;
for (uint8_t i = 0; i < 8; ++i)
{
// if (pull_up)
// io_set_pin(scl); // [Not ideal with pull-up]
io_input_pin(scl); // Release HIGH
if (pull_up)
io_set_pin(scl);
I2C_DELAY(I2C_DEFAULT_SCL_HIGH_PERIOD);
#ifdef I2C_ALLOW_CLOCK_STRETCH
uint8_t retries = I2C_DEFAULT_MAX_BUS_RETRIES;
while (io_test_pin(scl) == false) // Clock stretch requested?
{
I2C_DELAY(I2C_DEFAULT_BUS_WAIT);
if (--retries == 0)
{
debug_log_ex("I2C:R ");
debug_log_hex(scl);
debug_blink_rev(5);
return false;
}
}
#endif // I2C_ALLOW_CLOCK_STRETCH
(*value) |= ((io_test_pin(sda) ? 0x1 : 0x0) << (7 - i)); // MSB first
if (pull_up)
io_clear_pin(scl);
io_output_pin(scl); // Drive LOW (not ideal with pull-up)
// if (pull_up)
// io_clear_pin(scl);
I2C_DELAY(I2C_DEFAULT_SCL_LOW_PERIOD);
}
// Not necessary to ACK since it's only this one byte
return true;
}
bool i2c_read2_ex(io_pin_t sda, io_pin_t scl, uint8_t addr, uint8_t subaddr, uint8_t* value, bool pull_up)
{
if (_i2c_start_ex(sda, scl, pull_up) == false)
return false;
if (_i2c_write_byte_ex(sda, scl, addr & ~0x01, pull_up) == false)
{
#ifdef I2C_EXTRA_DEBUGGING
//debug_log_ex("R21:", false);
debug_log("R21");
//debug_log_hex(addr);
#endif // I2C_EXTRA_DEBUGGING
goto i2c_read2_fail;
}
if (_i2c_write_byte_ex(sda, scl, subaddr, pull_up) == false)
{
#ifdef I2C_EXTRA_DEBUGGING
//debug_log_ex("R22:", false);
debug_log("R22");
//debug_log_hex(subaddr);
#endif // I2C_EXTRA_DEBUGGING
goto i2c_read2_fail;
}
io_input_pin(scl);
if (pull_up)
io_set_pin(scl);
I2C_DELAY(I2C_DEFAULT_BUS_WAIT);
if (_i2c_start_ex(sda, scl, pull_up) == false)
{
return false;
}
if (_i2c_write_byte_ex(sda, scl, addr | 0x01, pull_up) == false)
{
#ifdef I2C_EXTRA_DEBUGGING
//debug_log_ex("R23:", false);
debug_log("R23");
//debug_log_hex(addr);
#endif // I2C_EXTRA_DEBUGGING
goto i2c_read2_fail;
}
if (_i2c_read_byte_ex(sda, scl, value, pull_up) == false)
{
#ifdef I2C_EXTRA_DEBUGGING
//debug_log_ex("R24:", false);
debug_log("R24");
//debug_log_hex(*value);
#endif // I2C_EXTRA_DEBUGGING
goto i2c_read2_fail;
}
if (_i2c_stop_ex(sda, scl, pull_up) == false)
{
#ifdef I2C_EXTRA_DEBUGGING
debug_log("R25");
#endif // I2C_EXTRA_DEBUGGING
}
return true;
i2c_read2_fail:
_i2c_abort_ex(sda, scl, pull_up);
return false;
}
bool i2c_write_ex(io_pin_t sda, io_pin_t scl, uint8_t addr, uint8_t subaddr, uint8_t value, bool pull_up)
{
if (_i2c_start_ex(sda, scl, pull_up) == false)
return false;
if (_i2c_write_byte_ex(sda, scl, addr, pull_up) == false)
goto i2c_write_fail;
if (_i2c_write_byte_ex(sda, scl, subaddr, pull_up) == false)
goto i2c_write_fail;
if (_i2c_write_byte_ex(sda, scl, value, pull_up) == false)
goto i2c_write_fail;
_i2c_stop_ex(sda, scl, pull_up);
return true;
i2c_write_fail:
_i2c_abort_ex(sda, scl, pull_up);
return false;
}
bool i2c_write(io_pin_t sda, io_pin_t scl, uint8_t addr, uint8_t subaddr, uint8_t value)
{
return i2c_write_ex(sda, scl, addr, subaddr, value, false);
}
bool i2c_read_ex(io_pin_t sda, io_pin_t scl, uint8_t addr, uint8_t subaddr, uint8_t* value, bool pull_up)
{
if (_i2c_start_ex(sda, scl, pull_up) == false)
return false;
if (_i2c_write_byte_ex(sda, scl, addr, pull_up) == false)
goto i2c_read_fail;
if (_i2c_write_byte_ex(sda, scl, subaddr, pull_up) == false)
goto i2c_read_fail;
if (_i2c_read_byte_ex(sda, scl, value, pull_up) == false)
goto i2c_read_fail;
_i2c_stop_ex(sda, scl, pull_up);
return true;
i2c_read_fail:
_i2c_abort_ex(sda, scl, pull_up);
return false;
}
bool i2c_read(io_pin_t sda, io_pin_t scl, uint8_t addr, uint8_t subaddr, uint8_t* value)
{
return i2c_read_ex(sda, scl, addr, subaddr, value, false);
}
void i2c_init_ex(io_pin_t sda, io_pin_t scl, bool pull_up)
{
_i2c_abort_ex(sda, scl, pull_up);
}
void i2c_init(io_pin_t sda, io_pin_t scl)
{
i2c_init_ex(sda, scl, false);
}
|
