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ac913e5c 1/*
50985c20 2 * This file is part of the libsigrok project.
ac913e5c
UH
3 *
4 * Copyright (C) 2012 Uwe Hermann <uwe@hermann-uwe.de>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
21/*
22 * Metex 14-bytes ASCII protocol parser.
23 *
24 * This should work for various multimeters which use this kind of protocol,
25 * even though there is some variation in which modes each DMM supports.
26 *
27 * It does _not_ work for all Metex DMMs, some use a quite different protocol.
28 */
29
30#include <string.h>
31#include <ctype.h>
32#include <math.h>
33#include <glib.h>
34#include "libsigrok.h"
35#include "libsigrok-internal.h"
36
37/* Message logging helpers with driver-specific prefix string. */
38#define DRIVER_LOG_DOMAIN "metex14: "
39#define sr_log(l, s, args...) sr_log(l, DRIVER_LOG_DOMAIN s, ## args)
40#define sr_spew(s, args...) sr_spew(DRIVER_LOG_DOMAIN s, ## args)
41#define sr_dbg(s, args...) sr_dbg(DRIVER_LOG_DOMAIN s, ## args)
42#define sr_info(s, args...) sr_info(DRIVER_LOG_DOMAIN s, ## args)
43#define sr_warn(s, args...) sr_warn(DRIVER_LOG_DOMAIN s, ## args)
44#define sr_err(s, args...) sr_err(DRIVER_LOG_DOMAIN s, ## args)
45
46static int parse_value(const uint8_t *buf, float *result)
47{
48 int i, sign, intval = 0, factor, decimal_point = 0, is_ol;
49 float floatval;
50 uint8_t digit;
51
52 /* Byte 3: Sign (' ' or '-') */
53 if (buf[3] == ' ') {
54 sign = 1;
55 } else if (buf[3] == '-') {
56 sign = -1;
57 } else {
58 sr_err("Invalid sign byte: 0x%02x.", buf[3]);
59 return SR_ERR;
60 }
61
62 /* Bytes 5-7: Over limit (various forms) */
63 is_ol = 0;
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64 is_ol += (!strncmp((char *)&buf[5], ".OL", 3)) ? 1 : 0;
65 is_ol += (!strncmp((char *)&buf[5], "O.L", 3)) ? 1 : 0;
66 is_ol += (!strncmp((char *)&buf[5], "OL.", 3)) ? 1 : 0;
67 is_ol += (!strncmp((char *)&buf[5], " OL", 3)) ? 1 : 0;
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68 if (is_ol != 0) {
69 sr_spew("Over limit.");
70 *result = INFINITY;
71 return SR_OK;
72 }
73
74 /* Bytes 4-8: Value (up to 4 digits) and decimal point */
75 factor = 1000;
76 for (i = 0; i < 5; i++) {
77 digit = buf[4 + i];
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78 /* Convert spaces to '0', so that we can parse them. */
79 if (digit == ' ')
80 digit = '0';
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81 if (digit == '.') {
82 decimal_point = i;
83 } else if (isdigit(digit)) {
84 intval += (digit - '0') * factor;
85 factor /= 10;
86 } else {
87 sr_err("Invalid digit byte: 0x%02x.", digit);
88 return SR_ERR;
89 }
90 }
91
92 floatval = (float)intval;
93
94 /* Decimal point position */
95 if (decimal_point == 0 || decimal_point == 4) {
96 /* TODO: Doesn't happen? */
97 } else if (decimal_point == 1) {
98 floatval /= 1000;
99 } else if (decimal_point == 2) {
100 floatval /= 100;
101 } else if (decimal_point == 3) {
102 floatval /= 10;
103 } else {
104 sr_err("Invalid decimal point position: %d.", decimal_point);
105 return SR_ERR;
106 }
107
108 /* Apply sign. */
109 floatval *= sign;
110
111 sr_spew("The display value is %f.", floatval);
112
113 *result = floatval;
114
115 return SR_OK;
116}
117
118static void parse_flags(const char *buf, struct metex14_info *info)
119{
120 /* Bytes 0-1: Measurement mode */
121 /* Note: Protocol doesn't distinguish "resistance" from "beep" mode. */
122 info->is_ac = !strncmp(buf, "AC", 2);
123 info->is_dc = !strncmp(buf, "DC", 2);
124 info->is_resistance = !strncmp(buf, "OH", 2);
125 info->is_capacity = !strncmp(buf, "CA", 2);
126 info->is_temperature = !strncmp(buf, "TE", 2);
127 info->is_diode = !strncmp(buf, "DI", 2);
128 info->is_frequency = !strncmp(buf, "FR", 2);
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129 info->is_gain = !strncmp(buf, "DB", 2);
130 info->is_hfe = !strncmp(buf, "HF", 2);
131
132 /*
133 * Note: "DB" shows the logarithmic ratio of input voltage to a
134 * pre-stored (user-changeable) value in the DMM.
135 */
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136
137 if (info->is_dc || info->is_ac)
138 info->is_volt = TRUE;
139
140 /* Byte 2: Always space (0x20). */
141
142 /* Bytes 3-8: See parse_value(). */
143
144 /* Bytes 9-12: Unit */
3ebc9b59 145 if (!strncmp(buf + 9, " A", 4))
ac913e5c 146 info->is_ampere = TRUE;
3ebc9b59 147 else if (!strncmp(buf + 9, " mA", 4))
ac913e5c 148 info->is_milli = info->is_ampere = TRUE;
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149 else if (!strncmp(buf + 9, " uA", 4))
150 info->is_micro = info->is_ampere = TRUE;
3ebc9b59 151 else if (!strncmp(buf + 9, " V", 4))
ac913e5c 152 info->is_volt = TRUE;
3ebc9b59 153 else if (!strncmp(buf + 9, " mV", 4))
ac913e5c 154 info->is_milli = info->is_volt = TRUE;
3ebc9b59 155 else if (!strncmp(buf + 9, " Ohm", 4))
ac913e5c 156 info->is_ohm = TRUE;
3ebc9b59 157 else if (!strncmp(buf + 9, "KOhm", 4))
ac913e5c 158 info->is_kilo = info->is_ohm = TRUE;
3ebc9b59 159 else if (!strncmp(buf + 9, "MOhm", 4))
ac913e5c 160 info->is_mega = info->is_ohm = TRUE;
3ebc9b59 161 else if (!strncmp(buf + 9, " nF", 4))
ac913e5c 162 info->is_nano = info->is_farad = TRUE;
3ebc9b59 163 else if (!strncmp(buf + 9, " uF", 4))
ac913e5c 164 info->is_micro = info->is_farad = TRUE;
3ebc9b59 165 else if (!strncmp(buf + 9, " KHz", 4))
ac913e5c 166 info->is_kilo = info->is_hertz = TRUE;
3ebc9b59 167 else if (!strncmp(buf + 9, " C", 4))
ac913e5c 168 info->is_celsius = TRUE;
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169 else if (!strncmp(buf + 9, " DB", 4))
170 info->is_decibel = TRUE;
171 else if (!strncmp(buf + 9, " ", 4))
172 info->is_unitless = TRUE;
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173
174 /* Byte 13: Always '\r' (carriage return, 0x0d, 13) */
175}
176
177static void handle_flags(struct sr_datafeed_analog *analog, float *floatval,
178 const struct metex14_info *info)
179{
180 /* Factors */
181 if (info->is_nano)
182 *floatval /= 1000000000;
183 if (info->is_micro)
184 *floatval /= 1000000;
185 if (info->is_milli)
186 *floatval /= 1000;
187 if (info->is_kilo)
188 *floatval *= 1000;
189 if (info->is_mega)
190 *floatval *= 1000000;
191
192 /* Measurement modes */
193 if (info->is_volt) {
194 analog->mq = SR_MQ_VOLTAGE;
195 analog->unit = SR_UNIT_VOLT;
196 }
197 if (info->is_ampere) {
198 analog->mq = SR_MQ_CURRENT;
199 analog->unit = SR_UNIT_AMPERE;
200 }
201 if (info->is_ohm) {
202 analog->mq = SR_MQ_RESISTANCE;
203 analog->unit = SR_UNIT_OHM;
204 }
205 if (info->is_hertz) {
206 analog->mq = SR_MQ_FREQUENCY;
207 analog->unit = SR_UNIT_HERTZ;
208 }
209 if (info->is_farad) {
210 analog->mq = SR_MQ_CAPACITANCE;
211 analog->unit = SR_UNIT_FARAD;
212 }
213 if (info->is_celsius) {
214 analog->mq = SR_MQ_TEMPERATURE;
215 analog->unit = SR_UNIT_CELSIUS;
216 }
217 if (info->is_diode) {
218 analog->mq = SR_MQ_VOLTAGE;
219 analog->unit = SR_UNIT_VOLT;
220 }
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221 if (info->is_gain) {
222 analog->mq = SR_MQ_GAIN;
223 analog->unit = SR_UNIT_DECIBEL_VOLT;
224 }
225 if (info->is_hfe) {
226 analog->mq = SR_MQ_GAIN;
227 analog->unit = SR_UNIT_UNITLESS;
228 }
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229
230 /* Measurement related flags */
231 if (info->is_ac)
232 analog->mqflags |= SR_MQFLAG_AC;
233 if (info->is_dc)
234 analog->mqflags |= SR_MQFLAG_DC;
235}
236
237static gboolean flags_valid(const struct metex14_info *info)
238{
239 int count;
240
241 /* Does the packet have more than one multiplier? */
242 count = 0;
243 count += (info->is_nano) ? 1 : 0;
244 count += (info->is_micro) ? 1 : 0;
245 count += (info->is_milli) ? 1 : 0;
246 count += (info->is_kilo) ? 1 : 0;
247 count += (info->is_mega) ? 1 : 0;
248 if (count > 1) {
249 sr_err("More than one multiplier detected in packet.");
250 return FALSE;
251 }
252
253 /* Does the packet "measure" more than one type of value? */
254 count = 0;
255 count += (info->is_ac) ? 1 : 0;
256 count += (info->is_dc) ? 1 : 0;
257 count += (info->is_resistance) ? 1 : 0;
258 count += (info->is_capacity) ? 1 : 0;
259 count += (info->is_temperature) ? 1 : 0;
260 count += (info->is_diode) ? 1 : 0;
261 count += (info->is_frequency) ? 1 : 0;
262 if (count > 1) {
263 sr_err("More than one measurement type detected in packet.");
264 return FALSE;
265 }
266
267 /* Both AC and DC set? */
268 if (info->is_ac && info->is_dc) {
269 sr_err("Both AC and DC flags detected in packet.");
270 return FALSE;
271 }
272
273 return TRUE;
274}
275
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276SR_PRIV int sr_metex14_packet_request(struct sr_serial_dev_inst *serial)
277{
278 const uint8_t wbuf = 'D';
279
280 sr_spew("Requesting DMM packet.");
281
282 return (serial_write(serial, &wbuf, 1) == 1) ? SR_OK : SR_ERR;
283}
284
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285SR_PRIV gboolean sr_metex14_packet_valid(const uint8_t *buf)
286{
287 struct metex14_info info;
288
289 memset(&info, 0x00, sizeof(struct metex14_info));
290 parse_flags((const char *)buf, &info);
291
292 if (!flags_valid(&info))
293 return FALSE;
294
295 if (buf[13] != '\r')
296 return FALSE;
297
298 return TRUE;
299}
300
301/**
302 * Parse a protocol packet.
303 *
1fbab466 304 * @param buf Buffer containing the protocol packet. Must not be NULL.
ac913e5c 305 * @param floatval Pointer to a float variable. That variable will be modified
1fbab466 306 * in-place depending on the protocol packet. Must not be NULL.
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307 * @param analog Pointer to a struct sr_datafeed_analog. The struct will be
308 * filled with data according to the protocol packet.
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309 * Must not be NULL.
310 * @param info Pointer to a struct metex14_info. The struct will be filled
311 * with data according to the protocol packet. Must not be NULL.
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312 *
313 * @return SR_OK upon success, SR_ERR upon failure. Upon errors, the
314 * 'analog' variable contents are undefined and should not be used.
315 */
316SR_PRIV int sr_metex14_parse(const uint8_t *buf, float *floatval,
1fbab466 317 struct sr_datafeed_analog *analog, void *info)
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318{
319 int ret;
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320 struct metex14_info *info_local;
321
322 info_local = (struct metex14_info *)info;
ac913e5c 323
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324 /* Don't print byte 13. That one contains the carriage return. */
325 sr_dbg("DMM packet: \"%.13s\"", buf);
326
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327 if ((ret = parse_value(buf, floatval)) != SR_OK) {
328 sr_err("Error parsing value: %d.", ret);
329 return ret;
330 }
331
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332 memset(info_local, 0x00, sizeof(struct metex14_info));
333 parse_flags((const char *)buf, info_local);
334 handle_flags(analog, floatval, info_local);
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335
336 return SR_OK;
337}