2 * This file is part of the libsigrok project.
4 * Copyright (C) 2012 Alexandru Gagniuc <mr.nuke.me@gmail.com>
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.
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.
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/>.
23 #define MAX_PACKET_LEN 22
25 /* Flags passed from the DMM. */
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;
32 struct bm850_command {
42 struct brymen_header {
56 * We only have one command because we only support the BM-857. However, the
57 * driver is easily extensible to support more models, as the protocols are
61 BM_CMD_REQUEST_READING = 0x00,
64 static int bm_send_command(uint8_t command, uint8_t arg1, uint8_t arg2,
65 struct sr_serial_dev_inst *serial)
67 struct bm850_command cmdout;
75 cmdout.checksum = arg1 ^ arg2;
79 /* TODO: How to compute the checksum? Hardware seems to ignore it. */
81 /* Request reading. */
82 written = serial_write_blocking(serial, &cmdout, sizeof(cmdout),
83 serial_timeout(serial, sizeof(cmdout)));
84 if (written != sizeof(cmdout))
90 SR_PRIV int brymen_packet_request(struct sr_serial_dev_inst *serial)
92 return bm_send_command(BM_CMD_REQUEST_READING, 0, 0, serial);
95 SR_PRIV int brymen_packet_length(const uint8_t *buf, int *len)
97 struct brymen_header *hdr;
104 /* Did we receive a complete header yet? */
105 if (buflen < sizeof(*hdr))
106 return PACKET_NEED_MORE_DATA;
108 if (hdr->dle != 0x10 || hdr->stx != 0x02)
109 return PACKET_INVALID_HEADER;
111 /* Our packet includes the header, the payload, and the tail. */
112 packet_len = sizeof(*hdr) + hdr->len + sizeof(struct brymen_tail);
114 /* In case we pick up an invalid header, limit our search. */
115 if (packet_len > MAX_PACKET_LEN) {
116 sr_spew("Header specifies an invalid payload length: %i.",
118 return PACKET_INVALID_HEADER;
122 sr_spew("Expecting a %d-byte packet.", *len);
123 return PACKET_HEADER_OK;
126 SR_PRIV gboolean brymen_packet_is_valid(const uint8_t *buf)
128 struct brymen_header *hdr;
129 struct brymen_tail *tail;
134 payload = (uint8_t *)(buf + sizeof(struct brymen_header));
137 tail = (void *)(payload + hdr->len);
139 for (i = 0; i< hdr->len; i++)
140 chksum ^= payload[i];
142 if (tail->checksum != chksum) {
143 sr_dbg("Packet has invalid checksum 0x%.2x. Expected 0x%.2x.",
144 chksum, tail->checksum);
151 static int parse_value(const char *txt, size_t len, float *floatval)
154 char c, buf[32], *dst;
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.
164 if (len >= sizeof(buf)) {
165 sr_err("Insufficient text conversion buffer size.");
170 while (txt < txt_end && *txt) {
178 /* Check for overflow, or get the number value. */
179 if (strstr(buf, "+OL")) {
180 *floatval = +INFINITY;
183 if (strstr(buf, "-OL")) {
184 *floatval = -INFINITY;
187 if (strstr(buf, "OL")) {
188 *floatval = INFINITY;
191 ret = sr_atof_ascii(buf, floatval);
198 static void parse_flags(const uint8_t *bfunc, struct brymen_flags *info)
200 info->is_low_batt = (bfunc[3] & (1 << 7)) != 0;
202 info->is_decibel = (bfunc[1] & (1 << 5)) != 0;
203 info->is_duty_cycle = (bfunc[1] & (1 << 3)) != 0;
204 info->is_hertz = (bfunc[1] & (1 << 2)) != 0;
205 info->is_amp = (bfunc[1] & (1 << 1)) != 0;
206 info->is_beep = (bfunc[1] & (1 << 0)) != 0;
208 info->is_ohm = (bfunc[0] & (1 << 7)) != 0;
209 info->is_fahrenheit = (bfunc[0] & (1 << 6)) != 0;
210 info->is_celsius = (bfunc[0] & (1 << 5)) != 0;
211 info->is_diode = (bfunc[0] & (1 << 4)) != 0;
212 info->is_capacitance = (bfunc[0] & (1 << 3)) != 0;
213 info->is_volt = (bfunc[0] & (1 << 2)) != 0;
214 info->is_dc = (bfunc[0] & (1 << 1)) != 0;
215 info->is_ac = (bfunc[0] & (1 << 0)) != 0;
218 SR_PRIV int brymen_parse(const uint8_t *buf, float *floatval,
219 struct sr_datafeed_analog *analog, void *info)
221 struct brymen_flags flags;
222 struct brymen_header *hdr;
233 bfunc = (uint8_t *)(buf + sizeof(struct brymen_header));
234 txt = (const char *)&bfunc[4];
235 txtlen = hdr->len - 4;
236 sr_dbg("DMM bfunc: %02x %02x %02x %02x, text '%.*s'",
237 bfunc[3], bfunc[2], bfunc[1], bfunc[0], txtlen, txt);
239 memset(&flags, 0, sizeof(flags));
240 parse_flags(bfunc, &flags);
241 if (flags.is_decibel && flags.is_ohm) {
243 * The reference impedance for the dBm function is in an
244 * unexpected format. Naive conversion of non-space chars
245 * gives incorrect results. Isolate the 4..1200 Ohms value
246 * instead, ignore the "0." and exponent parts of the
249 if (strncmp(txt, " 0.", strlen(" 0.")) == 0 && strstr(txt, " E")) {
250 txt = &txt[strlen(" 0.")];
251 txtlen -= strlen(" 0.");
252 p = strchr(txt, 'E');
257 if (flags.is_fahrenheit || flags.is_celsius) {
259 * The value text in temperature mode includes the C/F
260 * suffix between the mantissa and the exponent, which
261 * breaks the text to number conversion. Example data:
262 * " 0.0217CE+3". Remove the C/F unit identifier.
264 unit = strchr(txt, flags.is_fahrenheit ? 'F' : 'C');
269 ret = parse_value(txt, txtlen, floatval);
270 sr_dbg("floatval: %f, ret %d", *floatval, ret);
274 analog->meaning->mqflags = 0;
276 analog->meaning->mq = SR_MQ_VOLTAGE;
277 analog->meaning->unit = SR_UNIT_VOLT;
280 analog->meaning->mq = SR_MQ_CURRENT;
281 analog->meaning->unit = SR_UNIT_AMPERE;
284 if (flags.is_decibel)
285 analog->meaning->mq = SR_MQ_RESISTANCE;
286 else if (flags.is_beep)
287 analog->meaning->mq = SR_MQ_CONTINUITY;
289 analog->meaning->mq = SR_MQ_RESISTANCE;
290 analog->meaning->unit = SR_UNIT_OHM;
292 if (flags.is_hertz) {
293 analog->meaning->mq = SR_MQ_FREQUENCY;
294 analog->meaning->unit = SR_UNIT_HERTZ;
296 if (flags.is_duty_cycle) {
297 analog->meaning->mq = SR_MQ_DUTY_CYCLE;
298 analog->meaning->unit = SR_UNIT_PERCENTAGE;
300 if (flags.is_capacitance) {
301 analog->meaning->mq = SR_MQ_CAPACITANCE;
302 analog->meaning->unit = SR_UNIT_FARAD;
304 if (flags.is_fahrenheit) {
305 analog->meaning->mq = SR_MQ_TEMPERATURE;
306 analog->meaning->unit = SR_UNIT_FAHRENHEIT;
308 if (flags.is_celsius) {
309 analog->meaning->mq = SR_MQ_TEMPERATURE;
310 analog->meaning->unit = SR_UNIT_CELSIUS;
312 if (flags.is_capacitance) {
313 analog->meaning->mq = SR_MQ_CAPACITANCE;
314 analog->meaning->unit = SR_UNIT_FARAD;
318 * The high-end Brymen models have a configurable reference
319 * impedance for dBm measurements. When the meter's function
320 * is entered, or when the reference impedance is changed, the
321 * meter sends one packet with the value of the new reference.
322 * Both decibel and ohm flags are set in this case, so we must
323 * be careful to not clobber the resistance value from above,
324 * and only provide dBm when the measurement is shown and not
327 * The meter's response values also use an unexpected scale
328 * (always off by factor 1000, as if it was Watts not mW).
331 * bfunc: 00 00 20 80, text ' 0. 800 E+1' (reference)
332 * bfunc: 00 00 20 00, text '-0.3702 E-1' (measurement)
334 if (flags.is_decibel && !flags.is_ohm) {
335 analog->meaning->mq = SR_MQ_POWER;
336 analog->meaning->unit = SR_UNIT_DECIBEL_MW;
341 analog->meaning->mqflags |= SR_MQFLAG_DIODE | SR_MQFLAG_DC;
342 /* We can have both AC+DC in a single measurement. */
344 analog->meaning->mqflags |= SR_MQFLAG_AC;
346 analog->meaning->mqflags |= SR_MQFLAG_DC;
348 if (flags.is_low_batt)
349 sr_warn("Low battery!");