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
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
|
/****************************************************************************
*
* Copyright (C) 2012 PX4 Development Team. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name PX4 nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/**
* @file ms5611.cpp
* Driver for the MS5611 barometric pressure sensor connected via I2C.
*/
#include <nuttx/config.h>
#include <drivers/device/i2c.h>
#include <sys/types.h>
#include <stdint.h>
#include <stdbool.h>
#include <stdlib.h>
#include <semaphore.h>
#include <string.h>
#include <fcntl.h>
#include <poll.h>
#include <errno.h>
#include <stdio.h>
#include <math.h>
#include <unistd.h>
#include <nuttx/arch.h>
#include <nuttx/wqueue.h>
#include <nuttx/clock.h>
#include <arch/board/board.h>
#include <drivers/drv_hrt.h>
#include <systemlib/perf_counter.h>
#include <systemlib/err.h>
#include <drivers/drv_baro.h>
/* oddly, ERROR is not defined for c++ */
#ifdef ERROR
# undef ERROR
#endif
static const int ERROR = -1;
#ifndef CONFIG_SCHED_WORKQUEUE
# error This requires CONFIG_SCHED_WORKQUEUE.
#endif
/**
* Calibration PROM as reported by the device.
*/
#pragma pack(push,1)
struct ms5611_prom_s {
uint16_t factory_setup;
uint16_t c1_pressure_sens;
uint16_t c2_pressure_offset;
uint16_t c3_temp_coeff_pres_sens;
uint16_t c4_temp_coeff_pres_offset;
uint16_t c5_reference_temp;
uint16_t c6_temp_coeff_temp;
uint16_t serial_and_crc;
};
/**
* Grody hack for crc4()
*/
union ms5611_prom_u {
uint16_t c[8];
struct ms5611_prom_s s;
};
#pragma pack(pop)
class MS5611 : public device::I2C
{
public:
MS5611(int bus);
~MS5611();
virtual int init();
virtual ssize_t read(struct file *filp, char *buffer, size_t buflen);
virtual int ioctl(struct file *filp, int cmd, unsigned long arg);
/**
* Diagnostics - print some basic information about the driver.
*/
void print_info();
protected:
virtual int probe();
private:
union ms5611_prom_u _prom;
struct work_s _work;
unsigned _measure_ticks;
unsigned _num_reports;
volatile unsigned _next_report;
volatile unsigned _oldest_report;
struct baro_report *_reports;
bool _collect_phase;
unsigned _measure_phase;
/* intermediate temperature values per MS5611 datasheet */
int32_t _TEMP;
int64_t _OFF;
int64_t _SENS;
/* altitude conversion calibration */
unsigned _msl_pressure; /* in kPa */
orb_advert_t _baro_topic;
perf_counter_t _sample_perf;
perf_counter_t _comms_errors;
perf_counter_t _buffer_overflows;
/**
* Test whether the device supported by the driver is present at a
* specific address.
*
* @param address The I2C bus address to probe.
* @return True if the device is present.
*/
int probe_address(uint8_t address);
/**
* Initialise the automatic measurement state machine and start it.
*
* @note This function is called at open and error time. It might make sense
* to make it more aggressive about resetting the bus in case of errors.
*/
void start_cycle();
/**
* Stop the automatic measurement state machine.
*/
void stop_cycle();
/**
* Perform a poll cycle; collect from the previous measurement
* and start a new one.
*
* This is the heart of the measurement state machine. This function
* alternately starts a measurement, or collects the data from the
* previous measurement.
*
* When the interval between measurements is greater than the minimum
* measurement interval, a gap is inserted between collection
* and measurement to provide the most recent measurement possible
* at the next interval.
*/
void cycle();
/**
* Static trampoline from the workq context; because we don't have a
* generic workq wrapper yet.
*
* @param arg Instance pointer for the driver that is polling.
*/
static void cycle_trampoline(void *arg);
/**
* Issue a measurement command for the current state.
*
* @return OK if the measurement command was successful.
*/
int measure();
/**
* Collect the result of the most recent measurement.
*/
int collect();
/**
* Send a reset command to the MS5611.
*
* This is required after any bus reset.
*/
int cmd_reset();
/**
* Read the MS5611 PROM
*
* @return OK if the PROM reads successfully.
*/
int read_prom();
/**
* PROM CRC routine ported from MS5611 application note
*
* @param n_prom Pointer to words read from PROM.
* @return True if the CRC matches.
*/
bool crc4(uint16_t *n_prom);
};
/* helper macro for handling report buffer indices */
#define INCREMENT(_x, _lim) do { _x++; if (_x >= _lim) _x = 0; } while(0)
/* helper macro for arithmetic - returns the square of the argument */
#define POW2(_x) ((_x) * (_x))
/*
* MS5611 internal constants and data structures.
*/
/* internal conversion time: 9.17 ms, so should not be read at rates higher than 100 Hz */
#define MS5611_CONVERSION_INTERVAL 10000 /* microseconds */
#define MS5611_MEASUREMENT_RATIO 3 /* pressure measurements per temperature measurement */
#define MS5611_BUS PX4_I2C_BUS_ONBOARD
#define MS5611_ADDRESS_1 PX4_I2C_OBDEV_MS5611 /* address select pins pulled high (PX4FMU series v1.6+) */
#define MS5611_ADDRESS_2 0x77 /* address select pins pulled low (PX4FMU prototypes) */
#define ADDR_RESET_CMD 0x1E /* write to this address to reset chip */
#define ADDR_CMD_CONVERT_D1 0x48 /* write to this address to start temperature conversion */
#define ADDR_CMD_CONVERT_D2 0x58 /* write to this address to start pressure conversion */
#define ADDR_DATA 0x00 /* address of 3 bytes / 32bit pressure data */
#define ADDR_PROM_SETUP 0xA0 /* address of 8x 2 bytes factory and calibration data */
#define ADDR_PROM_C1 0xA2 /* address of 6x 2 bytes calibration data */
/*
* Driver 'main' command.
*/
extern "C" __EXPORT int ms5611_main(int argc, char *argv[]);
MS5611::MS5611(int bus) :
I2C("MS5611", BARO_DEVICE_PATH, bus, 0, 400000),
_measure_ticks(0),
_num_reports(0),
_next_report(0),
_oldest_report(0),
_reports(nullptr),
_collect_phase(false),
_measure_phase(0),
_TEMP(0),
_OFF(0),
_SENS(0),
_msl_pressure(101325),
_baro_topic(-1),
_sample_perf(perf_alloc(PC_ELAPSED, "ms5611_read")),
_comms_errors(perf_alloc(PC_COUNT, "ms5611_comms_errors")),
_buffer_overflows(perf_alloc(PC_COUNT, "ms5611_buffer_overflows"))
{
// enable debug() calls
_debug_enabled = true;
// work_cancel in the dtor will explode if we don't do this...
memset(&_work, 0, sizeof(_work));
}
MS5611::~MS5611()
{
/* make sure we are truly inactive */
stop_cycle();
/* free any existing reports */
if (_reports != nullptr)
delete[] _reports;
}
int
MS5611::init()
{
int ret = ERROR;
/* do I2C init (and probe) first */
if (I2C::init() != OK)
goto out;
/* allocate basic report buffers */
_num_reports = 2;
_reports = new struct baro_report[_num_reports];
if (_reports == nullptr)
goto out;
_oldest_report = _next_report = 0;
/* get a publish handle on the baro topic */
memset(&_reports[0], 0, sizeof(_reports[0]));
_baro_topic = orb_advertise(ORB_ID(sensor_baro), &_reports[0]);
if (_baro_topic < 0)
debug("failed to create sensor_baro object");
ret = OK;
out:
return ret;
}
int
MS5611::probe()
{
_retries = 10;
if ((OK == probe_address(MS5611_ADDRESS_1)) ||
(OK == probe_address(MS5611_ADDRESS_2))) {
/*
* Disable retries; we may enable them selectively in some cases,
* but the device gets confused if we retry some of the commands.
*/
_retries = 0;
return OK;
}
return -EIO;
}
int
MS5611::probe_address(uint8_t address)
{
/* select the address we are going to try */
set_address(address);
/* send reset command */
if (OK != cmd_reset())
return -EIO;
/* read PROM */
if (OK != read_prom())
return -EIO;
return OK;
}
ssize_t
MS5611::read(struct file *filp, char *buffer, size_t buflen)
{
unsigned count = buflen / sizeof(struct baro_report);
int ret = 0;
/* buffer must be large enough */
if (count < 1)
return -ENOSPC;
/* if automatic measurement is enabled */
if (_measure_ticks > 0) {
/*
* While there is space in the caller's buffer, and reports, copy them.
* Note that we may be pre-empted by the workq thread while we are doing this;
* we are careful to avoid racing with them.
*/
while (count--) {
if (_oldest_report != _next_report) {
memcpy(buffer, _reports + _oldest_report, sizeof(*_reports));
ret += sizeof(_reports[0]);
INCREMENT(_oldest_report, _num_reports);
}
}
/* if there was no data, warn the caller */
return ret ? ret : -EAGAIN;
}
/* manual measurement - run one conversion */
/* XXX really it'd be nice to lock against other readers here */
do {
_measure_phase = 0;
_oldest_report = _next_report = 0;
/* do temperature first */
if (OK != measure()) {
ret = -EIO;
break;
}
usleep(MS5611_CONVERSION_INTERVAL);
if (OK != collect()) {
ret = -EIO;
break;
}
/* now do a pressure measurement */
if (OK != measure()) {
ret = -EIO;
break;
}
usleep(MS5611_CONVERSION_INTERVAL);
if (OK != collect()) {
ret = -EIO;
break;
}
/* state machine will have generated a report, copy it out */
memcpy(buffer, _reports, sizeof(*_reports));
ret = sizeof(*_reports);
} while (0);
return ret;
}
int
MS5611::ioctl(struct file *filp, int cmd, unsigned long arg)
{
switch (cmd) {
case SENSORIOCSPOLLRATE: {
switch (arg) {
/* switching to manual polling */
case SENSOR_POLLRATE_MANUAL:
stop_cycle();
_measure_ticks = 0;
return OK;
/* external signalling not supported */
case SENSOR_POLLRATE_EXTERNAL:
/* zero would be bad */
case 0:
return -EINVAL;
/* set default/max polling rate */
case SENSOR_POLLRATE_MAX:
case SENSOR_POLLRATE_DEFAULT: {
/* do we need to start internal polling? */
bool want_start = (_measure_ticks == 0);
/* set interval for next measurement to minimum legal value */
_measure_ticks = USEC2TICK(MS5611_CONVERSION_INTERVAL);
/* if we need to start the poll state machine, do it */
if (want_start)
start_cycle();
return OK;
}
/* adjust to a legal polling interval in Hz */
default: {
/* do we need to start internal polling? */
bool want_start = (_measure_ticks == 0);
/* convert hz to tick interval via microseconds */
unsigned ticks = USEC2TICK(1000000 / arg);
/* check against maximum rate */
if (ticks < USEC2TICK(MS5611_CONVERSION_INTERVAL))
return -EINVAL;
/* update interval for next measurement */
_measure_ticks = ticks;
/* if we need to start the poll state machine, do it */
if (want_start)
start_cycle();
return OK;
}
}
}
case SENSORIOCGPOLLRATE:
if (_measure_ticks == 0)
return SENSOR_POLLRATE_MANUAL;
return (1000 / _measure_ticks);
case SENSORIOCSQUEUEDEPTH: {
/* add one to account for the sentinel in the ring */
arg++;
/* lower bound is mandatory, upper bound is a sanity check */
if ((arg < 2) || (arg > 100))
return -EINVAL;
/* allocate new buffer */
struct baro_report *buf = new struct baro_report[arg];
if (nullptr == buf)
return -ENOMEM;
/* reset the measurement state machine with the new buffer, free the old */
stop_cycle();
delete[] _reports;
_num_reports = arg;
_reports = buf;
start_cycle();
return OK;
}
case SENSORIOCGQUEUEDEPTH:
return _num_reports - 1;
case SENSORIOCRESET:
/* XXX implement this */
return -EINVAL;
case BAROIOCSMSLPRESSURE:
/* range-check for sanity */
if ((arg < 80000) || (arg > 120000))
return -EINVAL;
_msl_pressure = arg;
return OK;
case BAROIOCGMSLPRESSURE:
return _msl_pressure;
default:
break;
}
/* give it to the superclass */
return I2C::ioctl(filp, cmd, arg);
}
void
MS5611::start_cycle()
{
/* reset the report ring and state machine */
_collect_phase = false;
_measure_phase = 0;
_oldest_report = _next_report = 0;
/* schedule a cycle to start things */
work_queue(HPWORK, &_work, (worker_t)&MS5611::cycle_trampoline, this, 1);
}
void
MS5611::stop_cycle()
{
work_cancel(HPWORK, &_work);
}
void
MS5611::cycle_trampoline(void *arg)
{
MS5611 *dev = (MS5611 *)arg;
dev->cycle();
}
void
MS5611::cycle()
{
int ret;
/* collection phase? */
if (_collect_phase) {
/* perform collection */
ret = collect();
if (ret != OK) {
if (ret == -6) {
/*
* The ms5611 seems to regularly fail to respond to
* its address; this happens often enough that we'd rather not
* spam the console with the message.
*/
} else {
log("collection error %d", ret);
}
/* reset the collection state machine and try again */
start_cycle();
return;
}
/* next phase is measurement */
_collect_phase = false;
/*
* Is there a collect->measure gap?
* Don't inject one after temperature measurements, so we can keep
* doing pressure measurements at something close to the desired rate.
*/
if ((_measure_phase != 0) &&
(_measure_ticks > USEC2TICK(MS5611_CONVERSION_INTERVAL))) {
/* schedule a fresh cycle call when we are ready to measure again */
work_queue(HPWORK,
&_work,
(worker_t)&MS5611::cycle_trampoline,
this,
_measure_ticks - USEC2TICK(MS5611_CONVERSION_INTERVAL));
return;
}
}
/* measurement phase */
ret = measure();
if (ret != OK) {
log("measure error %d", ret);
/* reset the collection state machine and try again */
start_cycle();
return;
}
/* next phase is collection */
_collect_phase = true;
/* schedule a fresh cycle call when the measurement is done */
work_queue(HPWORK,
&_work,
(worker_t)&MS5611::cycle_trampoline,
this,
USEC2TICK(MS5611_CONVERSION_INTERVAL));
}
int
MS5611::measure()
{
int ret;
/*
* In phase zero, request temperature; in other phases, request pressure.
*/
uint8_t cmd_data = (_measure_phase == 0) ? ADDR_CMD_CONVERT_D2 : ADDR_CMD_CONVERT_D1;
/*
* Send the command to begin measuring.
*
* Disable retries on this command; we can't know whether failure
* means the device did or did not see the write.
*/
_retries = 0;
ret = transfer(&cmd_data, 1, nullptr, 0);
if (OK != ret)
perf_count(_comms_errors);
return ret;
}
int
MS5611::collect()
{
int ret;
uint8_t cmd;
uint8_t data[3];
union {
uint8_t b[4];
uint32_t w;
} cvt;
/* read the most recent measurement */
cmd = 0;
perf_begin(_sample_perf);
/* this should be fairly close to the end of the conversion, so the best approximation of the time */
_reports[_next_report].timestamp = hrt_absolute_time();
/* it's OK to retry on collection, as it has no side-effects */
_retries = 3;
ret = transfer(&cmd, 1, &data[0], 3);
if (ret != OK) {
perf_count(_comms_errors);
return ret;
}
/* fetch the raw value */
cvt.b[0] = data[2];
cvt.b[1] = data[1];
cvt.b[2] = data[0];
cvt.b[3] = 0;
uint32_t raw = cvt.w;
/* handle a measurement */
if (_measure_phase == 0) {
/* temperature offset (in ADC units) */
int32_t dT = (int32_t)raw - ((int32_t)_prom.s.c5_reference_temp << 8);
/* absolute temperature in centidegrees - note intermediate value is outside 32-bit range */
_TEMP = 2000 + (int32_t)(((int64_t)dT * _prom.s.c6_temp_coeff_temp) >> 23);
/* base sensor scale/offset values */
_SENS = ((int64_t)_prom.s.c1_pressure_sens << 15) + (((int64_t)_prom.s.c3_temp_coeff_pres_sens * dT) >> 8);
_OFF = ((int64_t)_prom.s.c2_pressure_offset << 16) + (((int64_t)_prom.s.c4_temp_coeff_pres_offset * dT) >> 7);
/* temperature compensation */
if (_TEMP < 2000) {
int32_t T2 = POW2(dT) >> 31;
int64_t f = POW2((int64_t)_TEMP - 2000);
int64_t OFF2 = 5 * f >> 1;
int64_t SENS2 = 5 * f >> 2;
if (_TEMP < -1500) {
int64_t f2 = POW2(_TEMP + 1500);
OFF2 += 7 * f2;
SENS2 += 11 * f2 >> 1;
}
_TEMP -= T2;
_OFF -= OFF2;
_SENS -= SENS2;
}
} else {
/* pressure calculation, result in Pa */
int32_t P = (((raw * _SENS) >> 21) - _OFF) >> 15;
/* generate a new report */
_reports[_next_report].temperature = _TEMP / 100.0f;
_reports[_next_report].pressure = P / 100.0f; /* convert to millibar */
/* altitude calculations based on http://www.kansasflyer.org/index.asp?nav=Avi&sec=Alti&tab=Theory&pg=1 */
/*
* PERFORMANCE HINT:
*
* The single precision calculation is 50 microseconds faster than the double
* precision variant. It is however not obvious if double precision is required.
* Pending more inspection and tests, we'll leave the double precision variant active.
*
* Measurements:
* double precision: ms5611_read: 992 events, 258641us elapsed, min 202us max 305us
* single precision: ms5611_read: 963 events, 208066us elapsed, min 202us max 241us
*/
#if 0/* USE_FLOAT */
/* tropospheric properties (0-11km) for standard atmosphere */
const float T1 = 15.0f + 273.15f; /* temperature at base height in Kelvin */
const float a = -6.5f / 1000f; /* temperature gradient in degrees per metre */
const float g = 9.80665f; /* gravity constant in m/s/s */
const float R = 287.05f; /* ideal gas constant in J/kg/K */
/* current pressure at MSL in kPa */
float p1 = _msl_pressure / 1000.0f;
/* measured pressure in kPa */
float p = P / 1000.0f;
/*
* Solve:
*
* / -(aR / g) \
* | (p / p1) . T1 | - T1
* \ /
* h = ------------------------------- + h1
* a
*/
_reports[_next_report].altitude = (((powf((p / p1), (-(a * R) / g))) * T1) - T1) / a;
#else
/* tropospheric properties (0-11km) for standard atmosphere */
const double T1 = 15.0 + 273.15; /* temperature at base height in Kelvin */
const double a = -6.5 / 1000; /* temperature gradient in degrees per metre */
const double g = 9.80665; /* gravity constant in m/s/s */
const double R = 287.05; /* ideal gas constant in J/kg/K */
/* current pressure at MSL in kPa */
double p1 = _msl_pressure / 1000.0;
/* measured pressure in kPa */
double p = P / 1000.0;
/*
* Solve:
*
* / -(aR / g) \
* | (p / p1) . T1 | - T1
* \ /
* h = ------------------------------- + h1
* a
*/
_reports[_next_report].altitude = (((pow((p / p1), (-(a * R) / g))) * T1) - T1) / a;
#endif
/* publish it */
orb_publish(ORB_ID(sensor_baro), _baro_topic, &_reports[_next_report]);
/* post a report to the ring - note, not locked */
INCREMENT(_next_report, _num_reports);
/* if we are running up against the oldest report, toss it */
if (_next_report == _oldest_report) {
perf_count(_buffer_overflows);
INCREMENT(_oldest_report, _num_reports);
}
/* notify anyone waiting for data */
poll_notify(POLLIN);
}
/* update the measurement state machine */
INCREMENT(_measure_phase, MS5611_MEASUREMENT_RATIO + 1);
perf_end(_sample_perf);
return OK;
}
int
MS5611::cmd_reset()
{
unsigned old_retrycount = _retries;
uint8_t cmd = ADDR_RESET_CMD;
int result;
/* bump the retry count */
_retries = 10;
result = transfer(&cmd, 1, nullptr, 0);
_retries = old_retrycount;
return result;
}
int
MS5611::read_prom()
{
uint8_t prom_buf[2];
union {
uint8_t b[2];
uint16_t w;
} cvt;
/*
* Wait for PROM contents to be in the device (2.8 ms) in the case we are
* called immediately after reset.
*/
usleep(3000);
/* read and convert PROM words */
for (int i = 0; i < 8; i++) {
uint8_t cmd = ADDR_PROM_SETUP + (i * 2);
if (OK != transfer(&cmd, 1, &prom_buf[0], 2))
break;
/* assemble 16 bit value and convert from big endian (sensor) to little endian (MCU) */
cvt.b[0] = prom_buf[1];
cvt.b[1] = prom_buf[0];
_prom.c[i] = cvt.w;
}
/* calculate CRC and return success/failure accordingly */
return crc4(&_prom.c[0]) ? OK : -EIO;
}
bool
MS5611::crc4(uint16_t *n_prom)
{
int16_t cnt;
uint16_t n_rem;
uint16_t crc_read;
uint8_t n_bit;
n_rem = 0x00;
/* save the read crc */
crc_read = n_prom[7];
/* remove CRC byte */
n_prom[7] = (0xFF00 & (n_prom[7]));
for (cnt = 0; cnt < 16; cnt++) {
/* uneven bytes */
if (cnt & 1) {
n_rem ^= (uint8_t)((n_prom[cnt >> 1]) & 0x00FF);
} else {
n_rem ^= (uint8_t)(n_prom[cnt >> 1] >> 8);
}
for (n_bit = 8; n_bit > 0; n_bit--) {
if (n_rem & 0x8000) {
n_rem = (n_rem << 1) ^ 0x3000;
} else {
n_rem = (n_rem << 1);
}
}
}
/* final 4 bit remainder is CRC value */
n_rem = (0x000F & (n_rem >> 12));
n_prom[7] = crc_read;
/* return true if CRCs match */
return (0x000F & crc_read) == (n_rem ^ 0x00);
}
void
MS5611::print_info()
{
perf_print_counter(_sample_perf);
perf_print_counter(_comms_errors);
perf_print_counter(_buffer_overflows);
printf("poll interval: %u ticks\n", _measure_ticks);
printf("report queue: %u (%u/%u @ %p)\n",
_num_reports, _oldest_report, _next_report, _reports);
printf("TEMP: %d\n", _TEMP);
printf("SENS: %lld\n", _SENS);
printf("OFF: %lld\n", _OFF);
printf("MSL pressure: %10.4f\n", (double)(_msl_pressure / 100.f));
printf("factory_setup %u\n", _prom.s.factory_setup);
printf("c1_pressure_sens %u\n", _prom.s.c1_pressure_sens);
printf("c2_pressure_offset %u\n", _prom.s.c2_pressure_offset);
printf("c3_temp_coeff_pres_sens %u\n", _prom.s.c3_temp_coeff_pres_sens);
printf("c4_temp_coeff_pres_offset %u\n", _prom.s.c4_temp_coeff_pres_offset);
printf("c5_reference_temp %u\n", _prom.s.c5_reference_temp);
printf("c6_temp_coeff_temp %u\n", _prom.s.c6_temp_coeff_temp);
printf("serial_and_crc %u\n", _prom.s.serial_and_crc);
}
/**
* Local functions in support of the shell command.
*/
namespace ms5611
{
MS5611 *g_dev;
void start();
void test();
void reset();
void info();
void calibrate(unsigned altitude);
/**
* Start the driver.
*/
void
start()
{
int fd;
if (g_dev != nullptr)
errx(1, "already started");
/* create the driver */
g_dev = new MS5611(MS5611_BUS);
if (g_dev == nullptr)
goto fail;
if (OK != g_dev->init())
goto fail;
/* set the poll rate to default, starts automatic data collection */
fd = open(BARO_DEVICE_PATH, O_RDONLY);
if (fd < 0)
goto fail;
if (ioctl(fd, SENSORIOCSPOLLRATE, SENSOR_POLLRATE_DEFAULT) < 0)
goto fail;
exit(0);
fail:
if (g_dev != nullptr) {
delete g_dev;
g_dev = nullptr;
}
errx(1, "driver start failed");
}
/**
* Perform some basic functional tests on the driver;
* make sure we can collect data from the sensor in polled
* and automatic modes.
*/
void
test()
{
struct baro_report report;
ssize_t sz;
int ret;
int fd = open(BARO_DEVICE_PATH, O_RDONLY);
if (fd < 0)
err(1, "%s open failed (try 'ms5611 start' if the driver is not running)", BARO_DEVICE_PATH);
/* do a simple demand read */
sz = read(fd, &report, sizeof(report));
if (sz != sizeof(report))
err(1, "immediate read failed");
warnx("single read");
warnx("pressure: %10.4f", (double)report.pressure);
warnx("altitude: %11.4f", (double)report.altitude);
warnx("temperature: %8.4f", (double)report.temperature);
warnx("time: %lld", report.timestamp);
/* set the queue depth to 10 */
if (OK != ioctl(fd, SENSORIOCSQUEUEDEPTH, 10))
errx(1, "failed to set queue depth");
/* start the sensor polling at 2Hz */
if (OK != ioctl(fd, SENSORIOCSPOLLRATE, 2))
errx(1, "failed to set 2Hz poll rate");
/* read the sensor 5x and report each value */
for (unsigned i = 0; i < 5; i++) {
struct pollfd fds;
/* wait for data to be ready */
fds.fd = fd;
fds.events = POLLIN;
ret = poll(&fds, 1, 2000);
if (ret != 1)
errx(1, "timed out waiting for sensor data");
/* now go get it */
sz = read(fd, &report, sizeof(report));
if (sz != sizeof(report))
err(1, "periodic read failed");
warnx("periodic read %u", i);
warnx("pressure: %10.4f", (double)report.pressure);
warnx("altitude: %11.4f", (double)report.altitude);
warnx("temperature: %8.4f", (double)report.temperature);
warnx("time: %lld", report.timestamp);
}
errx(0, "PASS");
}
/**
* Reset the driver.
*/
void
reset()
{
int fd = open(BARO_DEVICE_PATH, O_RDONLY);
if (fd < 0)
err(1, "failed ");
if (ioctl(fd, SENSORIOCRESET, 0) < 0)
err(1, "driver reset failed");
if (ioctl(fd, SENSORIOCSPOLLRATE, SENSOR_POLLRATE_DEFAULT) < 0)
err(1, "driver poll restart failed");
exit(0);
}
/**
* Print a little info about the driver.
*/
void
info()
{
if (g_dev == nullptr)
errx(1, "driver not running");
printf("state @ %p\n", g_dev);
g_dev->print_info();
exit(0);
}
/**
* Calculate actual MSL pressure given current altitude
*/
void
calibrate(unsigned altitude)
{
struct baro_report report;
float pressure;
float p1;
int fd = open(BARO_DEVICE_PATH, O_RDONLY);
if (fd < 0)
err(1, "%s open failed (try 'ms5611 start' if the driver is not running)", BARO_DEVICE_PATH);
/* start the sensor polling at max */
if (OK != ioctl(fd, SENSORIOCSPOLLRATE, SENSOR_POLLRATE_MAX))
errx(1, "failed to set poll rate");
/* average a few measurements */
pressure = 0.0f;
for (unsigned i = 0; i < 20; i++) {
struct pollfd fds;
int ret;
ssize_t sz;
/* wait for data to be ready */
fds.fd = fd;
fds.events = POLLIN;
ret = poll(&fds, 1, 1000);
if (ret != 1)
errx(1, "timed out waiting for sensor data");
/* now go get it */
sz = read(fd, &report, sizeof(report));
if (sz != sizeof(report))
err(1, "sensor read failed");
pressure += report.pressure;
}
pressure /= 20; /* average */
pressure /= 10; /* scale from millibar to kPa */
/* tropospheric properties (0-11km) for standard atmosphere */
const float T1 = 15.0 + 273.15; /* temperature at base height in Kelvin */
const float a = -6.5 / 1000; /* temperature gradient in degrees per metre */
const float g = 9.80665f; /* gravity constant in m/s/s */
const float R = 287.05f; /* ideal gas constant in J/kg/K */
warnx("averaged pressure %10.4fkPa at %um", pressure, altitude);
p1 = pressure * (powf(((T1 + (a * (float)altitude)) / T1), (g / (a * R))));
warnx("calculated MSL pressure %10.4fkPa", p1);
/* save as integer Pa */
p1 *= 1000.0f;
if (ioctl(fd, BAROIOCSMSLPRESSURE, (unsigned long)p1) != OK)
err(1, "BAROIOCSMSLPRESSURE");
exit(0);
}
} // namespace
int
ms5611_main(int argc, char *argv[])
{
/*
* Start/load the driver.
*/
if (!strcmp(argv[1], "start"))
ms5611::start();
/*
* Test the driver/device.
*/
if (!strcmp(argv[1], "test"))
ms5611::test();
/*
* Reset the driver.
*/
if (!strcmp(argv[1], "reset"))
ms5611::reset();
/*
* Print driver information.
*/
if (!strcmp(argv[1], "info"))
ms5611::info();
/*
* Perform MSL pressure calibration given an altitude in metres
*/
if (!strcmp(argv[1], "calibrate")) {
if (argc < 2)
errx(1, "missing altitude");
long altitude = strtol(argv[2], nullptr, 10);
ms5611::calibrate(altitude);
}
errx(1, "unrecognised command, try 'start', 'test', 'reset' or 'info'");
}
|