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brymen-dmm: improve text to number conversion robustness, signed OL
[libsigrok.git] / src / hardware / brymen-dmm / parser.c
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601fb67c 1/*
c5d6f5cc 2 * This file is part of the libsigrok project.
601fb67c
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3 *
4 * Copyright (C) 2012 Alexandru Gagniuc <mr.nuke.me@gmail.com>
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 3 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, see <http://www.gnu.org/licenses/>.
18 */
19
6ec6c43b 20#include <config.h>
601fb67c 21#include "protocol.h"
601fb67c 22
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23#define MAX_PACKET_LEN 22
24
25/* Flags passed from the DMM. */
601fb67c 26struct brymen_flags {
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27 gboolean is_low_batt, is_decibel, is_duty_cycle, is_hertz, is_amp;
28 gboolean is_beep, is_ohm, is_fahrenheit, is_celsius, is_capacitance;
29 gboolean is_diode, is_volt, is_dc, is_ac;
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30};
31
32struct bm850_command {
33 uint8_t dle;
34 uint8_t stx;
35 uint8_t cmd;
36 uint8_t arg[2];
37 uint8_t checksum;
38 uint8_t dle2;
39 uint8_t etx;
40};
41
42struct brymen_header {
43 uint8_t dle;
44 uint8_t stx;
45 uint8_t cmd;
46 uint8_t len;
47};
48
49struct brymen_tail {
50 uint8_t checksum;
51 uint8_t dle;
52 uint8_t etx;
53};
54
55/*
56 * We only have one command because we only support the BM-857. However, the
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57 * driver is easily extensible to support more models, as the protocols are
58 * very similar.
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59 */
60enum {
61 BM_CMD_REQUEST_READING = 0x00,
62};
63
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64static int bm_send_command(uint8_t command, uint8_t arg1, uint8_t arg2,
65 struct sr_serial_dev_inst *serial)
66{
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67 struct bm850_command cmdout;
68 int written;
69
70 cmdout.dle = 0x10;
71 cmdout.stx = 0x02;
72 cmdout.cmd = command;
73 cmdout.arg[0] = arg1;
74 cmdout.arg[1] = arg2;
75 cmdout.checksum = arg1 ^ arg2;
76 cmdout.dle2 = 0x10;
77 cmdout.etx = 0x03;
78
79 /* TODO: How to compute the checksum? Hardware seems to ignore it. */
80
81 /* Request reading. */
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82 written = serial_write_blocking(serial, &cmdout, sizeof(cmdout),
83 serial_timeout(serial, sizeof(cmdout)));
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84 if (written != sizeof(cmdout))
85 return SR_ERR;
86
87 return SR_OK;
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88}
89
90SR_PRIV int brymen_packet_request(struct sr_serial_dev_inst *serial)
91{
92 return bm_send_command(BM_CMD_REQUEST_READING, 0, 0, serial);
93}
94
95SR_PRIV int brymen_packet_length(const uint8_t *buf, int *len)
96{
97 struct brymen_header *hdr;
601fb67c 98 int packet_len;
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99 size_t buflen;
100
101 buflen = *len;
102 hdr = (void *)buf;
103
601fb67c 104 /* Did we receive a complete header yet? */
c5d6f5cc 105 if (buflen < sizeof(*hdr))
601fb67c 106 return PACKET_NEED_MORE_DATA;
c5d6f5cc 107
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108 if (hdr->dle != 0x10 || hdr->stx != 0x02)
109 return PACKET_INVALID_HEADER;
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110
111 /* Our packet includes the header, the payload, and the tail. */
601fb67c 112 packet_len = sizeof(*hdr) + hdr->len + sizeof(struct brymen_tail);
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113
114 /* In case we pick up an invalid header, limit our search. */
115 if (packet_len > MAX_PACKET_LEN) {
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116 sr_spew("Header specifies an invalid payload length: %i.",
117 hdr->len);
118 return PACKET_INVALID_HEADER;
119 }
c5d6f5cc 120
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121 *len = packet_len;
122 sr_spew("Expecting a %d-byte packet.", *len);
123 return PACKET_HEADER_OK;
124}
125
126SR_PRIV gboolean brymen_packet_is_valid(const uint8_t *buf)
127{
128 struct brymen_header *hdr;
129 struct brymen_tail *tail;
130 int i;
131 uint8_t chksum = 0;
c5d6f5cc 132 uint8_t *payload;
176d785d 133
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134 payload = (uint8_t *)(buf + sizeof(struct brymen_header));
135
136 hdr = (void *)buf;
137 tail = (void *)(payload + hdr->len);
176d785d 138
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139 for (i = 0; i< hdr->len; i++)
140 chksum ^= payload[i];
176d785d 141
601fb67c 142 if (tail->checksum != chksum) {
c5d6f5cc 143 sr_dbg("Packet has invalid checksum 0x%.2x. Expected 0x%.2x.",
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144 chksum, tail->checksum);
145 return FALSE;
146 }
176d785d 147
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148 return TRUE;
149}
150
56213aa0 151static int parse_value(const char *txt, size_t len, float *floatval)
601fb67c 152{
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153 const char *txt_end;
154 char c, buf[32], *dst;
155 int ret;
156
157 /*
158 * The input text is not NUL terminated, the checksum follows
159 * the value text field. Spaces may interfere with the text to
160 * number conversion, especially with exponent parsing. Copy the
161 * input data to a terminated text buffer and strip spaces in the
162 * process, before running ASCIIZ string operations.
163 */
164 if (len >= sizeof(buf)) {
165 sr_err("Insufficient text conversion buffer size.");
166 return SR_ERR_BUG;
167 }
168 txt_end = txt + len;
169 dst = &buf[0];
170 while (txt < txt_end && *txt) {
171 c = *txt++;
172 if (c == ' ')
173 continue;
174 *dst++ = c;
175 }
176 *dst = '\0';
601fb67c 177
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178 /* Check for overflow, or get the number value. */
179 if (strstr(buf, "+OL")) {
180 *floatval = +INFINITY;
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181 return SR_OK;
182 }
56213aa0
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183 if (strstr(buf, "-OL")) {
184 *floatval = -INFINITY;
185 return SR_OK;
933e63a1 186 }
56213aa0
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187 if (strstr(buf, "OL")) {
188 *floatval = INFINITY;
189 return SR_OK;
190 }
191 ret = sr_atof_ascii(buf, floatval);
192 if (ret != SR_OK)
193 return ret;
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194
195 return SR_OK;
196}
c5d6f5cc 197
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198static void parse_flags(const uint8_t *buf, struct brymen_flags *info)
199{
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200 info->is_low_batt = (buf[4 + 3] & (1 << 7)) != 0;
201
202 info->is_decibel = (buf[4 + 1] & (1 << 5)) != 0;
203 info->is_duty_cycle = (buf[4 + 1] & (1 << 3)) != 0;
204 info->is_hertz = (buf[4 + 1] & (1 << 2)) != 0;
205 info->is_amp = (buf[4 + 1] & (1 << 1)) != 0;
206 info->is_beep = (buf[4 + 1] & (1 << 0)) != 0;
207
208 info->is_ohm = (buf[4 + 0] & (1 << 7)) != 0;
209 info->is_fahrenheit = (buf[4 + 0] & (1 << 6)) != 0;
210 info->is_celsius = (buf[4 + 0] & (1 << 5)) != 0;
211 info->is_diode = (buf[4 + 0] & (1 << 4)) != 0;
212 info->is_capacitance = (buf[4 + 0] & (1 << 3)) != 0;
213 info->is_volt = (buf[4 + 0] & (1 << 2)) != 0;
214 info->is_dc = (buf[4 + 0] & (1 << 1)) != 0;
215 info->is_ac = (buf[4 + 0] & (1 << 0)) != 0;
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216}
217
933e63a1 218SR_PRIV int brymen_parse(const uint8_t *buf, float *floatval,
1653c430 219 struct sr_datafeed_analog *analog, void *info)
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220{
221 struct brymen_flags flags;
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222 struct brymen_header *hdr;
223 uint8_t *bfunc;
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224 int asciilen;
225
226 (void)info;
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227
228 hdr = (void *)buf;
229 bfunc = (uint8_t *)(buf + sizeof(struct brymen_header));
230
1653c430 231 analog->meaning->mqflags = 0;
601fb67c 232
c5d6f5cc 233 /* Give some debug info about the package. */
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234 asciilen = hdr->len - 4;
235 sr_dbg("DMM flags: %.2x %.2x %.2x %.2x",
236 bfunc[3], bfunc[2], bfunc[1], bfunc[0]);
c5d6f5cc 237 /* Value is an ASCII string. */
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238 sr_dbg("DMM packet: \"%.*s\"", asciilen, bfunc + 4);
239
240 parse_flags(buf, &flags);
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241 if (parse_value((const char *)(bfunc + 4), asciilen, floatval) != SR_OK)
242 return SR_ERR;
601fb67c 243
c5d6f5cc 244 if (flags.is_volt) {
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245 analog->meaning->mq = SR_MQ_VOLTAGE;
246 analog->meaning->unit = SR_UNIT_VOLT;
601fb67c 247 }
c5d6f5cc 248 if (flags.is_amp) {
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249 analog->meaning->mq = SR_MQ_CURRENT;
250 analog->meaning->unit = SR_UNIT_AMPERE;
601fb67c 251 }
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252 if (flags.is_ohm) {
253 if (flags.is_beep)
1653c430 254 analog->meaning->mq = SR_MQ_CONTINUITY;
601fb67c 255 else
1653c430
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256 analog->meaning->mq = SR_MQ_RESISTANCE;
257 analog->meaning->unit = SR_UNIT_OHM;
601fb67c 258 }
c5d6f5cc 259 if (flags.is_hertz) {
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260 analog->meaning->mq = SR_MQ_FREQUENCY;
261 analog->meaning->unit = SR_UNIT_HERTZ;
601fb67c 262 }
c5d6f5cc 263 if (flags.is_duty_cycle) {
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264 analog->meaning->mq = SR_MQ_DUTY_CYCLE;
265 analog->meaning->unit = SR_UNIT_PERCENTAGE;
601fb67c 266 }
c5d6f5cc 267 if (flags.is_capacitance) {
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268 analog->meaning->mq = SR_MQ_CAPACITANCE;
269 analog->meaning->unit = SR_UNIT_FARAD;
601fb67c 270 }
c5d6f5cc 271 if (flags.is_fahrenheit) {
1653c430
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272 analog->meaning->mq = SR_MQ_TEMPERATURE;
273 analog->meaning->unit = SR_UNIT_FAHRENHEIT;
601fb67c 274 }
c5d6f5cc 275 if (flags.is_celsius) {
1653c430
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276 analog->meaning->mq = SR_MQ_TEMPERATURE;
277 analog->meaning->unit = SR_UNIT_CELSIUS;
601fb67c 278 }
c5d6f5cc 279 if (flags.is_capacitance) {
1653c430
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280 analog->meaning->mq = SR_MQ_CAPACITANCE;
281 analog->meaning->unit = SR_UNIT_FARAD;
601fb67c 282 }
c5d6f5cc 283
601fb67c 284 /*
c5d6f5cc 285 * The high-end Brymen models have a configurable reference impedance.
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286 * When the reference impedance is changed, the DMM sends one packet
287 * with the value of the new reference impedance. Both decibel and ohm
288 * flags are set in this case, so we must be careful to correctly
c5d6f5cc 289 * identify the value as ohm, not dBmW.
601fb67c 290 */
c5d6f5cc 291 if (flags.is_decibel && !flags.is_ohm) {
1653c430
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292 analog->meaning->mq = SR_MQ_POWER;
293 analog->meaning->unit = SR_UNIT_DECIBEL_MW;
601fb67c
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294 /*
295 * For some reason, dBm measurements are sent by the multimeter
296 * with a value three orders of magnitude smaller than the
297 * displayed value.
c5d6f5cc 298 */
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299 *floatval *= 1000;
300 }
301
c5d6f5cc 302 if (flags.is_diode)
64aa214a 303 analog->meaning->mqflags |= SR_MQFLAG_DIODE | SR_MQFLAG_DC;
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304 /* We can have both AC+DC in a single measurement. */
305 if (flags.is_ac)
1653c430 306 analog->meaning->mqflags |= SR_MQFLAG_AC;
c5d6f5cc 307 if (flags.is_dc)
1653c430 308 analog->meaning->mqflags |= SR_MQFLAG_DC;
601fb67c 309
c5d6f5cc 310 if (flags.is_low_batt)
11addc89 311 sr_warn("Low battery!");
601fb67c
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312
313 return SR_OK;
c5d6f5cc 314}