libsigrok/hardware/common/dmm/metex14.c

/*
 * This file is part of the libsigrok project.
 *
 * Copyright (C) 2012-2013 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"

#define LOG_PREFIX "metex14"

static int parse_value(const uint8_t *buf, float *result)
{
	int i, is_ol, cnt;
	char valstr[7 + 1];

	/* Strip all spaces from bytes 2-8. */
	memset(&valstr, 0, 7 + 1);
	for (i = 0, cnt = 0; i < 7; i++) {
		if (buf[2 + i] != ' ')
			valstr[cnt++] = buf[2 + i];
	}

	/* Bytes 5-7: Over limit (various forms) */
	is_ol = 0;
	is_ol += (!strcasecmp((const char *)&valstr, ".OL")) ? 1 : 0;
	is_ol += (!strcasecmp((const char *)&valstr, "O.L")) ? 1 : 0;
	is_ol += (!strcasecmp((const char *)&valstr, "OL.")) ? 1 : 0;
	is_ol += (!strcasecmp((const char *)&valstr, "OL")) ? 1 : 0;
	is_ol += (!strcasecmp((const char *)&valstr, "-.OL")) ? 1 : 0;
	is_ol += (!strcasecmp((const char *)&valstr, "-O.L")) ? 1 : 0;
	is_ol += (!strcasecmp((const char *)&valstr, "-OL.")) ? 1 : 0;
	is_ol += (!strcasecmp((const char *)&valstr, "-OL")) ? 1 : 0;
	if (is_ol != 0) {
		sr_spew("Over limit.");
		*result = INFINITY;
		return SR_OK;
	}

	/* Bytes 2-8: Sign, value (up to 5 digits) and decimal point */
	sscanf((const char *)&valstr, "%f", result);

	sr_spew("The display value is %f.", *result);

	return SR_OK;
}

static void parse_flags(const char *buf, struct metex14_info *info)
{
	int i, cnt;
	char unit[4 + 1];
	const char *u;

	/* 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);
	info->is_gain        = !strncmp(buf, "DB", 2);
	info->is_hfe         = !strncmp(buf, "HF", 2);

	/*
	 * Note: "DB" shows the logarithmic ratio of input voltage to a
	 * pre-stored (user-changeable) value in the DMM.
	 */

	if (info->is_dc || info->is_ac)
		info->is_volt = TRUE;

	/* Bytes 2-8: See parse_value(). */

	/* Strip all spaces from bytes 9-12. */
	memset(&unit, 0, 4 + 1);
	for (i = 0, cnt = 0; i < 4; i++) {
		if (buf[9 + i] != ' ')
			unit[cnt++] = buf[9 + i];
	}

	/* Bytes 9-12: Unit */
	u = (const char *)&unit;
	if (!strcasecmp(u, "A"))
		info->is_ampere = TRUE;
	else if (!strcasecmp(u, "mA"))
		info->is_milli = info->is_ampere = TRUE;
	else if (!strcasecmp(u, "uA"))
		info->is_micro = info->is_ampere = TRUE;
	else if (!strcasecmp(u, "V"))
		info->is_volt = TRUE;
	else if (!strcasecmp(u, "mV"))
		info->is_milli = info->is_volt = TRUE;
	else if (!strcasecmp(u, "Ohm"))
		info->is_ohm = TRUE;
	else if (!strcasecmp(u, "KOhm"))
		info->is_kilo = info->is_ohm = TRUE;
	else if (!strcasecmp(u, "MOhm"))
		info->is_mega = info->is_ohm = TRUE;
	else if (!strcasecmp(u, "pF"))
		info->is_pico = info->is_farad = TRUE;
	else if (!strcasecmp(u, "nF"))
		info->is_nano = info->is_farad = TRUE;
	else if (!strcasecmp(u, "uF"))
		info->is_micro = info->is_farad = TRUE;
	else if (!strcasecmp(u, "KHz"))
		info->is_kilo = info->is_hertz = TRUE;
	else if (!strcasecmp(u, "C"))
		info->is_celsius = TRUE;
	else if (!strcasecmp(u, "DB"))
		info->is_decibel = TRUE;
	else if (!strcasecmp(u, ""))
		info->is_unitless = 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_pico)
		*floatval /= 1000000000000ULL;
	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;
	}
	if (info->is_gain) {
		analog->mq = SR_MQ_GAIN;
		analog->unit = SR_UNIT_DECIBEL_VOLT;
	}
	if (info->is_hfe) {
		analog->mq = SR_MQ_GAIN;
		analog->unit = SR_UNIT_UNITLESS;
	}

	/* Measurement related flags */
	if (info->is_ac)
		analog->mqflags |= SR_MQFLAG_AC;
	if (info->is_dc)
		analog->mqflags |= SR_MQFLAG_DC;
	if (info->is_diode)
		analog->mqflags |= SR_MQFLAG_DIODE;
}

static gboolean flags_valid(const struct metex14_info *info)
{
	int count;

	/* Does the packet have more than one multiplier? */
	count = 0;
	count += (info->is_pico) ? 1 : 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_dbg("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_dbg("More than one measurement type detected in packet.");
		return FALSE;
	}

	/* Both AC and DC set? */
	if (info->is_ac && info->is_dc) {
		sr_dbg("Both AC and DC flags detected in packet.");
		return FALSE;
	}

	return TRUE;
}

#ifdef HAVE_LIBSERIALPORT
SR_PRIV int sr_metex14_packet_request(struct sr_serial_dev_inst *serial)
{
	const uint8_t wbuf = 'D';

	sr_spew("Requesting DMM packet.");

	return (serial_write(serial, &wbuf, 1) == 1) ? SR_OK : SR_ERR;
}
#endif

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. Must not be NULL.
 * @param floatval Pointer to a float variable. That variable will be modified
 *                 in-place depending on the protocol packet. Must not be NULL.
 * @param analog Pointer to a struct sr_datafeed_analog. The struct will be
 *               filled with data according to the protocol packet.
 *               Must not be NULL.
 * @param info Pointer to a struct metex14_info. The struct will be filled
 *             with data according to the protocol packet. Must not be NULL.
 *
 * @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, void *info)
{
	int ret;
	struct metex14_info *info_local;

	info_local = (struct metex14_info *)info;

	/* Don't print byte 13. That one contains the carriage return. */
	sr_dbg("DMM packet: \"%.13s\"", buf);

	if ((ret = parse_value(buf, floatval)) != SR_OK) {
		sr_dbg("Error parsing value: %d.", ret);
		return ret;
	}

	memset(info_local, 0x00, sizeof(struct metex14_info));
	parse_flags((const char *)buf, info_local);
	handle_flags(analog, floatval, info_local);

	return SR_OK;
}