+/*
+ * This file is part of the libsigrok project.
+ *
+ * Copyright (C) 2014 Aurelien Jacobs <aurel@gnuage.org>
+ * Copyright (C) 2019-2020 Gerhard Sittig <gerhard.sittig@gmx.net>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/**
+ * @file
+ *
+ * Brymen BM52x serial protocol parser. The USB protocol (for the cable)
+ * and the packet description (for the meter) were retrieved from:
+ * http://brymen.com/product-html/Download2.html
+ * http://brymen.com/product-html/PD02BM520s_protocolDL.html
+ * http://brymen.com/product-html/images/DownloadList/ProtocolList/BM520-BM520s_List/BM520-BM520s-10000-count-professional-dual-display-mobile-logging-DMMs-protocol.zip
+ */
+
+/*
+ * TODO
+ * - This DMM packet parser exclusively supports live readings (vendor
+ * documentation refers to it as "real-time download" aka RTD). A HID
+ * report is sent which results in three HID reports in response which
+ * carry 24 bytes with LCD indicator bitfields (and a few literals to
+ * synchronize to the byte stream). Reading back previous recordings
+ * ("memory data sets" in the vendor documentation) involve different
+ * types of requests, and several of them, and result in a different
+ * number of response reports while their interpretation differs, too,
+ * of course. None of this fits the serial-dmm approach, and needs to
+ * get addressed later.
+ * - Configurable sample rate, range 20/s rate up to 600s period.
+ * - Multiple sessions, one function per session, up to 999 "session
+ * pages" (recordings with their sequence of measurement values).
+ * - Up to 87000 (single display) or 43500 (dual display) measurements
+ * total on BM525s.
+ * - Request 0x00, 0x00, 0x52, 0x88 to request the HEAD of recordings.
+ * Request 0x00, 0x00, 0x52, 0x89 to request the NEXT memory chunk.
+ * Request 0x00, 0x00, 0x52, 0x8a to re-request the CURR memory chunk
+ * (repetition when transmission failed detectably?).
+ * - All these HID report requests result in four HID responses which
+ * carry 32 bytes (24 bytes of payload data, and a checksum) where
+ * application's fields can cross the boundary of HID reports and
+ * even response chunks.
+ * - Some of the meter's functions and indications cannot get expressed
+ * by means of sigrok MQ and flags terms. Some indicator's meaning is
+ * unknown or uncertain, and thus their state is not evaluated.
+ * - MAX-MIN, the span between extreme values, referred to as Vp-p.
+ * - AVG is not available in BM525s and BM521s.
+ * - LoZ, eliminating ghost voltages.
+ * - LPF, low pass filter.
+ * - dBm is a BM829s feature only, not available in BM525s.
+ * - low battery, emits sr_warn() but isn't seen in the feed.
+ * - @, 4-20mA loop, % (main display, left hand side), Hi/Lo. Some of
+ * these are in the vendor's documentation for the DMM packet but not
+ * supported by the BM525s device which motivated the creation of the
+ * parser's and was used to test its operation.
+ * - It's a guess that the many undocumented bits (44 of them) are
+ * related to the bargraph (40 ticks, overflow, sign, 6/10 scale).
+ * - Should T1-T2 have a delta ("relative") decoration? But the meter's
+ * "relative" feature is flexible, accepts any display value as the
+ * reference, including min/max/diff when displayed upon activation.
+ * - The "beep jack" displays "InEr" in the secondary display. This is
+ * not caught here, no PC side message gets emitted.
+ */
+
+#include <config.h>
+#include <libsigrok/libsigrok.h>
+#include "libsigrok-internal.h"
+#include <math.h>
+#include <string.h>
+
+#define LOG_PREFIX "brymen-bm52x"
+
+#ifdef HAVE_SERIAL_COMM
+SR_PRIV int sr_brymen_bm52x_packet_request(struct sr_serial_dev_inst *serial)
+{
+ static const uint8_t request[] = { 0x00, 0x00, 0x52, 0x66, };
+
+ serial_write_nonblocking(serial, request, sizeof(request));
+
+ return SR_OK;
+}
+#endif
+
+SR_PRIV gboolean sr_brymen_bm52x_packet_valid(const uint8_t *buf)
+{
+ if (buf[16] != 0x52)
+ return FALSE;
+ if (buf[17] != 0x52)
+ return FALSE;
+ if (buf[18] != 0x52)
+ return FALSE;
+ if (buf[19] != 0x52)
+ return FALSE;
+
+ return TRUE;
+}
+
+/*
+ * Data bytes in the DMM packet encode LCD segments in an unusual order
+ * (bgcpafed) and in an unusual position (bit 4 being the decimal point
+ * for some digits, an additional indicator for others). Fortunately all
+ * eight digits encode their segments in identical ways across the bytes.
+ *
+ * These routines convert LCD segments to characters, and a section of the
+ * DMM packet (which corresponds to the primary or secondary display) to
+ * the text representation of the measurement's value, before regular text
+ * to number conversion is applied, and SI units and their prefixes get
+ * derived from more indicators. It's important to keep in mind similar
+ * indicators exist for main and secondary displays in different locations.
+ */
+
+static char brymen_bm52x_parse_digit(uint8_t b)
+{
+ switch (b & ~0x10) {
+ /* Sign. */
+ case 0x40: /* ------g */ return '-';
+ /* Decimal digits. */
+ case 0xaf: /* abcdef- */ return '0';
+ case 0xa0: /* -bc---- */ return '1';
+ case 0xcb: /* ab-de-g */ return '2';
+ case 0xe9: /* abcd--g */ return '3';
+ case 0xe4: /* -bc--fg */ return '4';
+ case 0x6d: /* a-cd-fg */ return '5';
+ case 0x6f: /* a-cdefg */ return '6';
+ case 0xa8: /* abc---- */ return '7';
+ case 0xef: /* abcdefg */ return '8';
+ case 0xed: /* abcd-fg */ return '9';
+ /* Temperature units. */
+ case 0x0f: /* a--def- */ return 'C';
+ case 0x4e: /* a---efg */ return 'F';
+ /* OL condition, and diode and "Auto" modes. */
+ case 0x07: /* ---def- */ return 'L';
+ case 0xe3: /* -bcde-g */ return 'd';
+ case 0x20: /* --c---- */ return 'i';
+ case 0x63: /* --cde-g */ return 'o';
+ case 0xee: /* abc-efg */ return 'A';
+ case 0x23: /* --cde-- */ return 'u';
+ case 0x47: /* ---defg */ return 't';
+ /* Blank digit. */
+ case 0x00: /* ------- */ return '\0';
+ /* Invalid or unknown segment combination. */
+ default:
+ sr_warn("Unknown encoding for digit: 0x%02x.", b);
+ return '\0';
+ }
+}
+
+static int brymen_bm52x_parse_digits(const uint8_t *pkt, size_t pktlen,
+ char *txtbuf, float *value, char *temp_unit, int *digits, int signflag)
+{
+ uint8_t byte;
+ char *txtptr, txtchar;
+ size_t pos;
+ int ret;
+
+ txtptr = txtbuf;
+ if (digits)
+ *digits = INT_MIN;
+
+ if (pkt[0] & signflag)
+ *txtptr++ = '-';
+ for (pos = 0; pos < pktlen; pos++) {
+ byte = pkt[1 + pos];
+ txtchar = brymen_bm52x_parse_digit(byte);
+ if (pos == 3 && (txtchar == 'C' || txtchar == 'F')) {
+ if (temp_unit)
+ *temp_unit = txtchar;
+ } else if (txtchar) {
+ *txtptr++ = txtchar;
+ if (digits)
+ (*digits)++;
+ }
+ if (pos < 3 && (byte & 0x10)) {
+ *txtptr++ = '.';
+ if (digits)
+ *digits = 0;
+ }
+ }
+ *txtptr = '\0';
+
+ if (digits && *digits < 0)
+ *digits = 0;
+
+ ret = value ? sr_atof_ascii(txtbuf, value) : SR_OK;
+ if (ret != SR_OK) {
+ sr_dbg("invalid float string: '%s'", txtbuf);
+ return ret;
+ }
+
+ return SR_OK;
+}
+
+/*
+ * Extract the measurement value and its properties for one of the
+ * meter's displays from the DMM packet.
+ */
+static void brymen_bm52x_parse(const uint8_t *buf, float *floatval,
+ struct sr_datafeed_analog *analog, size_t ch_idx)
+{
+ char txtbuf[16], temp_unit;
+ int ret, digits, scale;
+ int is_diode, is_auto, is_no_temp, is_ol, is_db, is_main_milli;
+ int is_mm_max, is_mm_min, is_mm_avg, is_mm_dash;
+
+ temp_unit = '\0';
+ if (ch_idx == 0) {
+ /*
+ * Main display. Note that _some_ of the second display's
+ * indicators are involved in the inspection of the _first_
+ * display's measurement value. So we have to get the
+ * second display's text buffer here, too.
+ */
+ (void)brymen_bm52x_parse_digits(&buf[7], 4, txtbuf,
+ NULL, NULL, NULL, 0);
+ is_diode = strcmp(txtbuf, "diod") == 0;
+ is_auto = strcmp(txtbuf, "Auto") == 0;
+ ret = brymen_bm52x_parse_digits(&buf[2], 4, txtbuf,
+ floatval, &temp_unit, &digits, 0x80);
+ is_ol = strstr(txtbuf, "0L") || strstr(txtbuf, "0.L");
+ is_no_temp = strcmp(txtbuf, "---C") == 0;
+ is_no_temp |= strcmp(txtbuf, "---F") == 0;
+ if (ret != SR_OK && !is_ol)
+ return;
+
+ /* SI unit, derived from meter's current function. */
+ is_db = buf[6] & 0x10;
+ is_main_milli = buf[14] & 0x40;
+ if (buf[14] & 0x20) {
+ analog->meaning->mq = SR_MQ_VOLTAGE;
+ analog->meaning->unit = SR_UNIT_VOLT;
+ if (is_diode) {
+ analog->meaning->mqflags |= SR_MQFLAG_DIODE;
+ analog->meaning->mqflags |= SR_MQFLAG_DC;
+ }
+ } else if (buf[14] & 0x10) {
+ analog->meaning->mq = SR_MQ_CURRENT;
+ analog->meaning->unit = SR_UNIT_AMPERE;
+ } else if (buf[14] & 0x01) {
+ analog->meaning->mq = SR_MQ_CAPACITANCE;
+ analog->meaning->unit = SR_UNIT_FARAD;
+ } else if (buf[14] & 0x02) {
+ analog->meaning->mq = SR_MQ_CONDUCTANCE;
+ analog->meaning->unit = SR_UNIT_SIEMENS;
+ } else if (buf[13] & 0x10) {
+ analog->meaning->mq = SR_MQ_FREQUENCY;
+ analog->meaning->unit = SR_UNIT_HERTZ;
+ } else if (buf[7] & 0x01) {
+ analog->meaning->mq = SR_MQ_CONTINUITY;
+ analog->meaning->unit = SR_UNIT_OHM;
+ } else if (buf[13] & 0x20) {
+ analog->meaning->mq = SR_MQ_RESISTANCE;
+ analog->meaning->unit = SR_UNIT_OHM;
+ } else if (is_db && is_main_milli) {
+ analog->meaning->mq = SR_MQ_POWER;
+ analog->meaning->unit = SR_UNIT_DECIBEL_MW;
+ } else if (buf[14] & 0x04) {
+ analog->meaning->mq = SR_MQ_DUTY_CYCLE;
+ analog->meaning->unit = SR_UNIT_PERCENTAGE;
+ } else if ((buf[2] & 0x09) && temp_unit) {
+ if (is_no_temp)
+ return;
+ analog->meaning->mq = SR_MQ_TEMPERATURE;
+ if (temp_unit == 'F')
+ analog->meaning->unit = SR_UNIT_FAHRENHEIT;
+ else
+ analog->meaning->unit = SR_UNIT_CELSIUS;
+ }
+
+ /*
+ * Remove the MIN/MAX/AVG indicators when all of them
+ * are shown at the same time (indicating that recording
+ * is active, but live readings are shown). This also
+ * removes the MAX-MIN (V p-p) indication which cannot
+ * get represented by SR_MQFLAG_* means.
+ *
+ * Keep the check conditions separate to simplify future
+ * maintenance when Vp-p gets added. Provide the value of
+ * currently unsupported modes just without flags (show
+ * the maximum amount of LCD content on screen that we
+ * can represent in sigrok).
+ */
+ is_mm_max = buf[1] & 0x01;
+ is_mm_min = buf[1] & 0x08;
+ is_mm_avg = buf[1] & 0x02;
+ is_mm_dash = buf[1] & 0x04;
+ if (is_mm_max && is_mm_min && is_mm_avg)
+ is_mm_max = is_mm_min = is_mm_avg = 0;
+ if (is_mm_max && is_mm_min && is_mm_dash)
+ is_mm_max = is_mm_min = 0;
+ if (is_mm_max && is_mm_min && !is_mm_dash)
+ is_mm_max = is_mm_min = 0;
+
+ /* AC/DC/Auto flags. Hold/Min/Max/Rel etc flags. */
+ if (buf[1] & 0x20)
+ analog->meaning->mqflags |= SR_MQFLAG_DC;
+ if (buf[1] & 0x10)
+ analog->meaning->mqflags |= SR_MQFLAG_AC;
+ if (buf[20] & 0x10)
+ analog->meaning->mqflags |= SR_MQFLAG_AUTORANGE;
+ if (buf[20] & 0x80)
+ analog->meaning->mqflags |= SR_MQFLAG_HOLD;
+ if (is_mm_max)
+ analog->meaning->mqflags |= SR_MQFLAG_MAX;
+ if (is_mm_min)
+ analog->meaning->mqflags |= SR_MQFLAG_MIN;
+ if (is_mm_avg)
+ analog->meaning->mqflags |= SR_MQFLAG_AVG;
+ if (buf[2] & 0x40)
+ analog->meaning->mqflags |= SR_MQFLAG_RELATIVE;
+
+ /*
+ * Remove the "dBm" indication's "m" indicator before the
+ * SI unit's prefixes get inspected. Avoids an interaction
+ * with the "milli" prefix. Strictly speaking BM525s does
+ * not support dBm, but other models do and we may want
+ * to share the protocol parser.
+ */
+ if (is_db)
+ is_main_milli = 0;
+
+ /* SI prefix. */
+ scale = 0;
+ if (buf[14] & 0x08) /* n */
+ scale = -9;
+ if (buf[14] & 0x80) /* u */
+ scale = -6;
+ if (is_main_milli) /* m */
+ scale = -3;
+ if (buf[13] & 0x80) /* k */
+ scale = +3;
+ if (buf[13] & 0x40) /* M */
+ scale = +6;
+ if (scale) {
+ *floatval *= pow(10, scale);
+ digits += -scale;
+ }
+
+ if (is_ol)
+ *floatval = INFINITY;
+
+ analog->encoding->digits = digits;
+ analog->spec->spec_digits = digits;
+ } else if (ch_idx == 1) {
+ /*
+ * Secondary display. Also inspect _some_ primary display
+ * data, to determine the secondary display's validity.
+ */
+ (void)brymen_bm52x_parse_digits(&buf[2], 4, txtbuf,
+ NULL, &temp_unit, NULL, 0x80);
+ ret = brymen_bm52x_parse_digits(&buf[7], 4, txtbuf,
+ floatval, NULL, &digits, 0x20);
+ is_diode = strcmp(txtbuf, "diod") == 0;
+ is_auto = strcmp(txtbuf, "Auto") == 0;
+ is_no_temp = strcmp(txtbuf, "---C") == 0;
+ is_no_temp |= strcmp(txtbuf, "---F") == 0;
+ if (is_diode || is_auto)
+ return;
+ if (is_no_temp)
+ return;
+
+ /* SI unit. */
+ if (buf[12] & 0x10) {
+ analog->meaning->mq = SR_MQ_VOLTAGE;
+ analog->meaning->unit = SR_UNIT_VOLT;
+ } else if (buf[12] & 0x20) {
+ analog->meaning->mq = SR_MQ_CURRENT;
+ if (buf[11] & 0x10)
+ analog->meaning->unit = SR_UNIT_PERCENTAGE;
+ else
+ analog->meaning->unit = SR_UNIT_AMPERE;
+ } else if (buf[13] & 0x02) {
+ analog->meaning->mq = SR_MQ_RESISTANCE;
+ analog->meaning->unit = SR_UNIT_OHM;
+ } else if (buf[12] & 0x02) {
+ analog->meaning->mq = SR_MQ_CONDUCTANCE;
+ analog->meaning->unit = SR_UNIT_SIEMENS;
+ } else if (buf[12] & 0x01) {
+ analog->meaning->mq = SR_MQ_CAPACITANCE;
+ analog->meaning->unit = SR_UNIT_FARAD;
+ } else if (buf[7] & 0x06) {
+ if (strstr(txtbuf, "---"))
+ return;
+ analog->meaning->mq = SR_MQ_TEMPERATURE;
+ if (temp_unit == 'F')
+ analog->meaning->unit = SR_UNIT_FAHRENHEIT;
+ else
+ analog->meaning->unit = SR_UNIT_CELSIUS;
+ } else if (buf[13] & 0x01) {
+ analog->meaning->mq = SR_MQ_FREQUENCY;
+ analog->meaning->unit = SR_UNIT_HERTZ;
+ } else if (buf[11] & 0x08) {
+ analog->meaning->mq = SR_MQ_DUTY_CYCLE;
+ analog->meaning->unit = SR_UNIT_PERCENTAGE;
+ }
+
+ /* DC/AC flags. */
+ if (buf[7] & 0x80)
+ analog->meaning->mqflags |= SR_MQFLAG_DC;
+ if (buf[7] & 0x40)
+ analog->meaning->mqflags |= SR_MQFLAG_AC;
+
+ /* SI prefix. */
+ scale = 0;
+ if (buf[12] & 0x04) /* n */
+ scale = -9;
+ if (buf[12] & 0x40) /* u */
+ scale = -6;
+ if (buf[12] & 0x80) /* m */
+ scale = -3;
+ if (buf[13] & 0x04) /* k */
+ scale = +3;
+ if (buf[13] & 0x08) /* M */
+ scale = +6;
+ if (scale) {
+ *floatval *= pow(10, scale);
+ digits += -scale;
+ }
+
+ analog->encoding->digits = digits;
+ analog->spec->spec_digits = digits;
+ }
+
+ if (buf[7] & 0x08)
+ sr_warn("Battery is low.");
+}
+
+SR_PRIV int sr_brymen_bm52x_parse(const uint8_t *buf, float *val,
+ struct sr_datafeed_analog *analog, void *info)
+{
+ struct brymen_bm52x_info *info_local;
+ size_t ch_idx;
+
+ /*
+ * Scan a portion of the received DMM packet which corresponds
+ * to the caller's specified display. Then prepare to scan a
+ * different portion of the packet for another display. This
+ * routine gets called multiple times for one received packet.
+ */
+ info_local = info;
+ ch_idx = info_local->ch_idx;
+ brymen_bm52x_parse(buf, val, analog, ch_idx);
+ info_local->ch_idx = ch_idx + 1;
+
+ return SR_OK;
+}
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