--- /dev/null
+/*
+ * This file is part of the sigrok project.
+ *
+ * Copyright (C) 2012 Uwe Hermann <uwe@hermann-uwe.de>
+ *
+ * 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 2 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, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/*
+ * Metex 14-bytes ASCII protocol parser.
+ *
+ * This should work for various multimeters which use this kind of protocol,
+ * even though there is some variation in which modes each DMM supports.
+ *
+ * It does _not_ work for all Metex DMMs, some use a quite different protocol.
+ */
+
+#include <string.h>
+#include <ctype.h>
+#include <math.h>
+#include <glib.h>
+#include "libsigrok.h"
+#include "libsigrok-internal.h"
+
+/* Message logging helpers with driver-specific prefix string. */
+#define DRIVER_LOG_DOMAIN "metex14: "
+#define sr_log(l, s, args...) sr_log(l, DRIVER_LOG_DOMAIN s, ## args)
+#define sr_spew(s, args...) sr_spew(DRIVER_LOG_DOMAIN s, ## args)
+#define sr_dbg(s, args...) sr_dbg(DRIVER_LOG_DOMAIN s, ## args)
+#define sr_info(s, args...) sr_info(DRIVER_LOG_DOMAIN s, ## args)
+#define sr_warn(s, args...) sr_warn(DRIVER_LOG_DOMAIN s, ## args)
+#define sr_err(s, args...) sr_err(DRIVER_LOG_DOMAIN s, ## args)
+
+static int parse_value(const uint8_t *buf, float *result)
+{
+ int i, sign, intval = 0, factor, decimal_point = 0, is_ol;
+ float floatval;
+ uint8_t digit;
+
+ /* Byte 3: Sign (' ' or '-') */
+ if (buf[3] == ' ') {
+ sign = 1;
+ } else if (buf[3] == '-') {
+ sign = -1;
+ } else {
+ sr_err("Invalid sign byte: 0x%02x.", buf[3]);
+ return SR_ERR;
+ }
+
+ /* Bytes 5-7: Over limit (various forms) */
+ is_ol = 0;
+ is_ol += !strncmp((char *)&buf[5], ".OL", 3);
+ is_ol += !strncmp((char *)&buf[5], "O.L", 3);
+ is_ol += !strncmp((char *)&buf[5], "OL.", 3);
+ is_ol += !strncmp((char *)&buf[5], " OL", 3);
+ if (is_ol != 0) {
+ sr_spew("Over limit.");
+ *result = INFINITY;
+ return SR_OK;
+ }
+
+ /* Bytes 4-8: Value (up to 4 digits) and decimal point */
+ factor = 1000;
+ for (i = 0; i < 5; i++) {
+ digit = buf[4 + i];
+ if (digit == '.') {
+ decimal_point = i;
+ } else if (isdigit(digit)) {
+ intval += (digit - '0') * factor;
+ factor /= 10;
+ } else {
+ sr_err("Invalid digit byte: 0x%02x.", digit);
+ return SR_ERR;
+ }
+ }
+
+ floatval = (float)intval;
+
+ /* Decimal point position */
+ if (decimal_point == 0 || decimal_point == 4) {
+ /* TODO: Doesn't happen? */
+ } else if (decimal_point == 1) {
+ floatval /= 1000;
+ } else if (decimal_point == 2) {
+ floatval /= 100;
+ } else if (decimal_point == 3) {
+ floatval /= 10;
+ } else {
+ sr_err("Invalid decimal point position: %d.", decimal_point);
+ return SR_ERR;
+ }
+
+ /* Apply sign. */
+ floatval *= sign;
+
+ sr_spew("The display value is %f.", floatval);
+
+ *result = floatval;
+
+ return SR_OK;
+}
+
+static void parse_flags(const char *buf, struct metex14_info *info)
+{
+ /* Bytes 0-1: Measurement mode */
+ /* Note: Protocol doesn't distinguish "resistance" from "beep" mode. */
+ info->is_ac = !strncmp(buf, "AC", 2);
+ info->is_dc = !strncmp(buf, "DC", 2);
+ info->is_resistance = !strncmp(buf, "OH", 2);
+ info->is_capacity = !strncmp(buf, "CA", 2);
+ info->is_temperature = !strncmp(buf, "TE", 2);
+ info->is_diode = !strncmp(buf, "DI", 2);
+ info->is_frequency = !strncmp(buf, "FR", 2);
+
+ if (info->is_dc || info->is_ac)
+ info->is_volt = TRUE;
+
+ /* Byte 2: Always space (0x20). */
+
+ /* Bytes 3-8: See parse_value(). */
+
+ /* Bytes 9-12: Unit */
+ if (!strcmp(buf + 9, " A"))
+ info->is_ampere = TRUE;
+ else if (!strcmp(buf + 9, " mA"))
+ info->is_milli = info->is_ampere = TRUE;
+ else if (!strcmp(buf + 9, " V"))
+ info->is_volt = TRUE;
+ else if (!strcmp(buf + 9, " mV"))
+ info->is_milli = info->is_volt = TRUE;
+ else if (!strcmp(buf + 9, " Ohm"))
+ info->is_ohm = TRUE;
+ else if (!strcmp(buf + 9, "KOhm"))
+ info->is_kilo = info->is_ohm = TRUE;
+ else if (!strcmp(buf + 9, "MOhm"))
+ info->is_mega = info->is_ohm = TRUE;
+ else if (!strcmp(buf + 9, " nF"))
+ info->is_nano = info->is_farad = TRUE;
+ else if (!strcmp(buf + 9, " uF"))
+ info->is_micro = info->is_farad = TRUE;
+ else if (!strcmp(buf + 9, " KHz"))
+ info->is_kilo = info->is_hertz = TRUE;
+ else if (!strcmp(buf + 9, " C"))
+ info->is_celsius = TRUE;
+
+ /* Byte 13: Always '\r' (carriage return, 0x0d, 13) */
+}
+
+static void handle_flags(struct sr_datafeed_analog *analog, float *floatval,
+ const struct metex14_info *info)
+{
+ /* Factors */
+ if (info->is_nano)
+ *floatval /= 1000000000;
+ if (info->is_micro)
+ *floatval /= 1000000;
+ if (info->is_milli)
+ *floatval /= 1000;
+ if (info->is_kilo)
+ *floatval *= 1000;
+ if (info->is_mega)
+ *floatval *= 1000000;
+
+ /* Measurement modes */
+ if (info->is_volt) {
+ analog->mq = SR_MQ_VOLTAGE;
+ analog->unit = SR_UNIT_VOLT;
+ }
+ if (info->is_ampere) {
+ analog->mq = SR_MQ_CURRENT;
+ analog->unit = SR_UNIT_AMPERE;
+ }
+ if (info->is_ohm) {
+ analog->mq = SR_MQ_RESISTANCE;
+ analog->unit = SR_UNIT_OHM;
+ }
+ if (info->is_hertz) {
+ analog->mq = SR_MQ_FREQUENCY;
+ analog->unit = SR_UNIT_HERTZ;
+ }
+ if (info->is_farad) {
+ analog->mq = SR_MQ_CAPACITANCE;
+ analog->unit = SR_UNIT_FARAD;
+ }
+ if (info->is_celsius) {
+ analog->mq = SR_MQ_TEMPERATURE;
+ analog->unit = SR_UNIT_CELSIUS;
+ }
+ if (info->is_diode) {
+ analog->mq = SR_MQ_VOLTAGE;
+ analog->unit = SR_UNIT_VOLT;
+ }
+
+ /* Measurement related flags */
+ if (info->is_ac)
+ analog->mqflags |= SR_MQFLAG_AC;
+ if (info->is_dc)
+ analog->mqflags |= SR_MQFLAG_DC;
+}
+
+static gboolean flags_valid(const struct metex14_info *info)
+{
+ int count;
+
+ /* Does the packet have more than one multiplier? */
+ count = 0;
+ count += (info->is_nano) ? 1 : 0;
+ count += (info->is_micro) ? 1 : 0;
+ count += (info->is_milli) ? 1 : 0;
+ count += (info->is_kilo) ? 1 : 0;
+ count += (info->is_mega) ? 1 : 0;
+ if (count > 1) {
+ sr_err("More than one multiplier detected in packet.");
+ return FALSE;
+ }
+
+ /* Does the packet "measure" more than one type of value? */
+ count = 0;
+ count += (info->is_ac) ? 1 : 0;
+ count += (info->is_dc) ? 1 : 0;
+ count += (info->is_resistance) ? 1 : 0;
+ count += (info->is_capacity) ? 1 : 0;
+ count += (info->is_temperature) ? 1 : 0;
+ count += (info->is_diode) ? 1 : 0;
+ count += (info->is_frequency) ? 1 : 0;
+ if (count > 1) {
+ sr_err("More than one measurement type detected in packet.");
+ return FALSE;
+ }
+
+ /* Both AC and DC set? */
+ if (info->is_ac && info->is_dc) {
+ sr_err("Both AC and DC flags detected in packet.");
+ return FALSE;
+ }
+
+ return TRUE;
+}
+
+SR_PRIV gboolean sr_metex14_packet_valid(const uint8_t *buf)
+{
+ struct metex14_info info;
+
+ memset(&info, 0x00, sizeof(struct metex14_info));
+ parse_flags((const char *)buf, &info);
+
+ if (!flags_valid(&info))
+ return FALSE;
+
+ if (buf[13] != '\r')
+ return FALSE;
+
+ return TRUE;
+}
+
+/**
+ * Parse a protocol packet.
+ *
+ * @param buf Buffer containing the protocol packet.
+ * @param floatval Pointer to a float variable. That variable will be modified
+ * in-place depending on the protocol packet.
+ * @param analog Pointer to a struct sr_datafeed_analog. The struct will be
+ * filled with data according to the protocol packet.
+ *
+ * @return SR_OK upon success, SR_ERR upon failure. Upon errors, the
+ * 'analog' variable contents are undefined and should not be used.
+ */
+SR_PRIV int sr_metex14_parse(const uint8_t *buf, float *floatval,
+ struct sr_datafeed_analog *analog,
+ struct metex14_info *info)
+{
+ int ret;
+
+ if ((ret = parse_value(buf, floatval)) != SR_OK) {
+ sr_err("Error parsing value: %d.", ret);
+ return ret;
+ }
+
+ memset(info, 0x00, sizeof(struct metex14_info));
+ parse_flags((const char *)buf, info);
+ handle_flags(analog, floatval, info);
+
+ return SR_OK;
+}
projects / libsigrok.git / commitdiff