--- /dev/null
+/*
+ * This file is part of the libsigrok project.
+ *
+ * Copyright (C) 2012 Alexandru Gagniuc <mr.nuke.me@gmail.com>
+ *
+ * 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/>.
+ */
+
+/*
+ * RadioShack 22-812 protocol parser.
+ *
+ * This protocol is currently encountered on the RadioShack 22-812 DMM.
+ * It is a 9-byte packet representing a 1:1 mapping of the LCD segments, hence
+ * the name rs9lcd.
+ *
+ * The chip is a bare die covered by a plastic blob. It is unclear if this chip
+ * and protocol is used on any other device.
+ */
+
+#include <string.h>
+#include <ctype.h>
+#include <math.h>
+#include <glib.h>
+#include "libsigrok.h"
+#include "libsigrok-internal.h"
+
+#define LOG_PREFIX "rs9lcd"
+
+/* Byte 1 of the packet, and the modes it represents */
+#define IND1_HZ (1 << 7)
+#define IND1_OHM (1 << 6)
+#define IND1_KILO (1 << 5)
+#define IND1_MEGA (1 << 4)
+#define IND1_FARAD (1 << 3)
+#define IND1_AMP (1 << 2)
+#define IND1_VOLT (1 << 1)
+#define IND1_MILI (1 << 0)
+/* Byte 2 of the packet, and the modes it represents */
+#define IND2_MICRO (1 << 7)
+#define IND2_NANO (1 << 6)
+#define IND2_DBM (1 << 5)
+#define IND2_SEC (1 << 4)
+#define IND2_DUTY (1 << 3)
+#define IND2_HFE (1 << 2)
+#define IND2_REL (1 << 1)
+#define IND2_MIN (1 << 0)
+/* Byte 7 of the packet, and the modes it represents */
+#define INFO_BEEP (1 << 7)
+#define INFO_DIODE (1 << 6)
+#define INFO_BAT (1 << 5)
+#define INFO_HOLD (1 << 4)
+#define INFO_NEG (1 << 3)
+#define INFO_AC (1 << 2)
+#define INFO_RS232 (1 << 1)
+#define INFO_AUTO (1 << 0)
+/* Instead of a decimal point, digit 4 carries the MAX flag */
+#define DIG4_MAX (1 << 3)
+/* Mask to remove the decimal point from a digit */
+#define DP_MASK (1 << 3)
+
+/* What the LCD values represent */
+#define LCD_0 0xd7
+#define LCD_1 0x50
+#define LCD_2 0xb5
+#define LCD_3 0xf1
+#define LCD_4 0x72
+#define LCD_5 0xe3
+#define LCD_6 0xe7
+#define LCD_7 0x51
+#define LCD_8 0xf7
+#define LCD_9 0xf3
+
+#define LCD_C 0x87
+#define LCD_E
+#define LCD_F
+#define LCD_h 0x66
+#define LCD_H 0x76
+#define LCD_I
+#define LCD_n
+#define LCD_P 0x37
+#define LCD_r
+
+enum {
+ MODE_DC_V = 0,
+ MODE_AC_V = 1,
+ MODE_DC_UA = 2,
+ MODE_DC_MA = 3,
+ MODE_DC_A = 4,
+ MODE_AC_UA = 5,
+ MODE_AC_MA = 6,
+ MODE_AC_A = 7,
+ MODE_OHM = 8,
+ MODE_FARAD = 9,
+ MODE_HZ = 10,
+ MODE_VOLT_HZ = 11, /* Dial set to V, Hz selected by Hz button */
+ MODE_AMP_HZ = 12, /* Dial set to A, Hz selected by Hz button */
+ MODE_DUTY = 13,
+ MODE_VOLT_DUTY = 14, /* Dial set to V, duty cycle selected */
+ MODE_AMP_DUTY = 15, /* Dial set to A, duty cycle selected */
+ MODE_WIDTH = 16,
+ MODE_VOLT_WIDTH = 17, /* Dial set to V, pulse width selected */
+ MODE_AMP_WIDTH = 18, /* Dial set to A, pulse width selected */
+ MODE_DIODE = 19,
+ MODE_CONT = 20,
+ MODE_HFE = 21,
+ MODE_LOGIC = 22,
+ MODE_DBM = 23,
+ /* MODE_EF = 24, */ /* Not encountered on any DMM */
+ MODE_TEMP = 25,
+ MODE_INVALID = 26,
+};
+
+enum {
+ READ_ALL,
+ READ_TEMP,
+};
+
+struct rs9lcd_packet {
+ uint8_t mode;
+ uint8_t indicatrix1;
+ uint8_t indicatrix2;
+ uint8_t digit4;
+ uint8_t digit3;
+ uint8_t digit2;
+ uint8_t digit1;
+ uint8_t info;
+ uint8_t checksum;
+};
+
+static gboolean checksum_valid(const struct rs9lcd_packet *rs_packet)
+{
+ uint8_t *raw;
+ uint8_t sum = 0;
+ int i;
+
+ raw = (void *)rs_packet;
+
+ for (i = 0; i < RS9LCD_PACKET_SIZE - 1; i++)
+ sum += raw[i];
+
+ /* This is just a funky constant added to the checksum. */
+ sum += 57;
+ sum -= rs_packet->checksum;
+ return (sum == 0);
+}
+
+static gboolean selection_good(const struct rs9lcd_packet *rs_packet)
+{
+ int count;
+
+ /* Does the packet have more than one multiplier? */
+ count = 0;
+ count += (rs_packet->indicatrix1 & IND1_KILO) ? 1 : 0;
+ count += (rs_packet->indicatrix1 & IND1_MEGA) ? 1 : 0;
+ count += (rs_packet->indicatrix1 & IND1_MILI) ? 1 : 0;
+ count += (rs_packet->indicatrix2 & IND2_MICRO) ? 1 : 0;
+ count += (rs_packet->indicatrix2 & IND2_NANO) ? 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 += (rs_packet->indicatrix1 & IND1_HZ) ? 1 : 0;
+ count += (rs_packet->indicatrix1 & IND1_OHM) ? 1 : 0;
+ count += (rs_packet->indicatrix1 & IND1_FARAD) ? 1 : 0;
+ count += (rs_packet->indicatrix1 & IND1_AMP) ? 1 : 0;
+ count += (rs_packet->indicatrix1 & IND1_VOLT) ? 1 : 0;
+ count += (rs_packet->indicatrix2 & IND2_DBM) ? 1 : 0;
+ count += (rs_packet->indicatrix2 & IND2_SEC) ? 1 : 0;
+ count += (rs_packet->indicatrix2 & IND2_DUTY) ? 1 : 0;
+ count += (rs_packet->indicatrix2 & IND2_HFE) ? 1 : 0;
+ if (count > 1) {
+ sr_dbg("More than one measurement type detected in packet.");
+ return FALSE;
+ }
+
+ return TRUE;
+}
+
+/*
+ * Since the 22-812 does not identify itself in any way, shape, or form,
+ * we really don't know for sure who is sending the data. We must use every
+ * possible check to filter out bad packets, especially since detection of the
+ * 22-812 depends on how well we can filter the packets.
+ */
+SR_PRIV gboolean sr_rs9lcd_packet_valid(const uint8_t *buf)
+{
+ const struct rs9lcd_packet *rs_packet = (void *)buf;
+
+ /*
+ * Check for valid mode first, before calculating the checksum. No
+ * point calculating the checksum, if we know we'll reject the packet.
+ */
+ if (!(rs_packet->mode < MODE_INVALID))
+ return FALSE;
+
+ if (!checksum_valid(rs_packet)) {
+ sr_spew("Packet with invalid checksum. Discarding.");
+ return FALSE;
+ }
+
+ if (!selection_good(rs_packet)) {
+ sr_spew("Packet with invalid selection bits. Discarding.");
+ return FALSE;
+ }
+
+ return TRUE;
+}
+
+static uint8_t decode_digit(uint8_t raw_digit)
+{
+ /* Take out the decimal point, so we can use a simple switch(). */
+ raw_digit &= ~DP_MASK;
+
+ switch (raw_digit) {
+ case 0x00:
+ case LCD_0:
+ return 0;
+ case LCD_1:
+ return 1;
+ case LCD_2:
+ return 2;
+ case LCD_3:
+ return 3;
+ case LCD_4:
+ return 4;
+ case LCD_5:
+ return 5;
+ case LCD_6:
+ return 6;
+ case LCD_7:
+ return 7;
+ case LCD_8:
+ return 8;
+ case LCD_9:
+ return 9;
+ default:
+ sr_dbg("Invalid digit byte: 0x%02x.", raw_digit);
+ return 0xff;
+ }
+}
+
+static double lcd_to_double(const struct rs9lcd_packet *rs_packet, int type)
+{
+ double rawval = 0, multiplier = 1;
+ uint8_t digit, raw_digit;
+ gboolean dp_reached = FALSE;
+ int i, end;
+
+ /* end = 1: Don't parse last digit. end = 0: Parse all digits. */
+ end = (type == READ_TEMP) ? 1 : 0;
+
+ /* We have 4 digits, and we start from the most significant. */
+ for (i = 3; i >= end; i--) {
+ raw_digit = *(&(rs_packet->digit4) + i);
+ digit = decode_digit(raw_digit);
+ if (digit == 0xff) {
+ rawval = NAN;
+ break;
+ }
+ /*
+ * Digit 1 does not have a decimal point. Instead, the decimal
+ * point is used to indicate MAX, so we must avoid testing it.
+ */
+ if ((i < 3) && (raw_digit & DP_MASK))
+ dp_reached = TRUE;
+ if (dp_reached)
+ multiplier /= 10;
+ rawval = rawval * 10 + digit;
+ }
+ rawval *= multiplier;
+ if (rs_packet->info & INFO_NEG)
+ rawval *= -1;
+
+ /* See if we need to multiply our raw value by anything. */
+ if (rs_packet->indicatrix1 & IND2_NANO)
+ rawval *= 1E-9;
+ else if (rs_packet->indicatrix2 & IND2_MICRO)
+ rawval *= 1E-6;
+ else if (rs_packet->indicatrix1 & IND1_MILI)
+ rawval *= 1E-3;
+ else if (rs_packet->indicatrix1 & IND1_KILO)
+ rawval *= 1E3;
+ else if (rs_packet->indicatrix1 & IND1_MEGA)
+ rawval *= 1E6;
+
+ return rawval;
+}
+
+static gboolean is_celsius(const struct rs9lcd_packet *rs_packet)
+{
+ return ((rs_packet->digit4 & ~DP_MASK) == LCD_C);
+}
+
+static gboolean is_shortcirc(const struct rs9lcd_packet *rs_packet)
+{
+ return ((rs_packet->digit2 & ~DP_MASK) == LCD_h);
+}
+
+static gboolean is_logic_high(const struct rs9lcd_packet *rs_packet)
+{
+ sr_spew("Digit 2: 0x%02x.", rs_packet->digit2 & ~DP_MASK);
+ return ((rs_packet->digit2 & ~DP_MASK) == LCD_H);
+}
+
+SR_PRIV int sr_rs9lcd_parse(const uint8_t *buf, float *floatval,
+ struct sr_datafeed_analog *analog, void *info)
+{
+ const struct rs9lcd_packet *rs_packet = (void *)buf;
+ double rawval;
+
+ (void)info;
+
+ rawval = lcd_to_double(rs_packet, READ_ALL);
+
+ switch (rs_packet->mode) {
+ case MODE_DC_V:
+ analog->mq = SR_MQ_VOLTAGE;
+ analog->unit = SR_UNIT_VOLT;
+ analog->mqflags |= SR_MQFLAG_DC;
+ break;
+ case MODE_AC_V:
+ analog->mq = SR_MQ_VOLTAGE;
+ analog->unit = SR_UNIT_VOLT;
+ analog->mqflags |= SR_MQFLAG_AC;
+ break;
+ case MODE_DC_UA: /* Fall through */
+ case MODE_DC_MA: /* Fall through */
+ case MODE_DC_A:
+ analog->mq = SR_MQ_CURRENT;
+ analog->unit = SR_UNIT_AMPERE;
+ analog->mqflags |= SR_MQFLAG_DC;
+ break;
+ case MODE_AC_UA: /* Fall through */
+ case MODE_AC_MA: /* Fall through */
+ case MODE_AC_A:
+ analog->mq = SR_MQ_CURRENT;
+ analog->unit = SR_UNIT_AMPERE;
+ analog->mqflags |= SR_MQFLAG_AC;
+ break;
+ case MODE_OHM:
+ analog->mq = SR_MQ_RESISTANCE;
+ analog->unit = SR_UNIT_OHM;
+ break;
+ case MODE_FARAD:
+ analog->mq = SR_MQ_CAPACITANCE;
+ analog->unit = SR_UNIT_FARAD;
+ break;
+ case MODE_CONT:
+ analog->mq = SR_MQ_CONTINUITY;
+ analog->unit = SR_UNIT_BOOLEAN;
+ rawval = is_shortcirc(rs_packet);
+ break;
+ case MODE_DIODE:
+ analog->mq = SR_MQ_VOLTAGE;
+ analog->unit = SR_UNIT_VOLT;
+ analog->mqflags |= SR_MQFLAG_DIODE | SR_MQFLAG_DC;
+ break;
+ case MODE_HZ: /* Fall through */
+ case MODE_VOLT_HZ: /* Fall through */
+ case MODE_AMP_HZ:
+ analog->mq = SR_MQ_FREQUENCY;
+ analog->unit = SR_UNIT_HERTZ;
+ break;
+ case MODE_LOGIC:
+ /*
+ * No matter whether or not we have an actual voltage reading,
+ * we are measuring voltage, so we set our MQ as VOLTAGE.
+ */
+ analog->mq = SR_MQ_VOLTAGE;
+ if (!isnan(rawval)) {
+ /* We have an actual voltage. */
+ analog->unit = SR_UNIT_VOLT;
+ } else {
+ /* We have either HI or LOW. */
+ analog->unit = SR_UNIT_BOOLEAN;
+ rawval = is_logic_high(rs_packet);
+ }
+ break;
+ case MODE_HFE:
+ analog->mq = SR_MQ_GAIN;
+ analog->unit = SR_UNIT_UNITLESS;
+ break;
+ case MODE_DUTY: /* Fall through */
+ case MODE_VOLT_DUTY: /* Fall through */
+ case MODE_AMP_DUTY:
+ analog->mq = SR_MQ_DUTY_CYCLE;
+ analog->unit = SR_UNIT_PERCENTAGE;
+ break;
+ case MODE_WIDTH: /* Fall through */
+ case MODE_VOLT_WIDTH: /* Fall through */
+ case MODE_AMP_WIDTH:
+ analog->mq = SR_MQ_PULSE_WIDTH;
+ analog->unit = SR_UNIT_SECOND;
+ break;
+ case MODE_TEMP:
+ analog->mq = SR_MQ_TEMPERATURE;
+ /* We need to reparse. */
+ rawval = lcd_to_double(rs_packet, READ_TEMP);
+ analog->unit = is_celsius(rs_packet) ?
+ SR_UNIT_CELSIUS : SR_UNIT_FAHRENHEIT;
+ break;
+ case MODE_DBM:
+ analog->mq = SR_MQ_POWER;
+ analog->unit = SR_UNIT_DECIBEL_MW;
+ analog->mqflags |= SR_MQFLAG_AC;
+ break;
+ default:
+ sr_dbg("Unknown mode: %d.", rs_packet->mode);
+ break;
+ }
+
+ if (rs_packet->info & INFO_HOLD)
+ analog->mqflags |= SR_MQFLAG_HOLD;
+ if (rs_packet->digit4 & DIG4_MAX)
+ analog->mqflags |= SR_MQFLAG_MAX;
+ if (rs_packet->indicatrix2 & IND2_MIN)
+ analog->mqflags |= SR_MQFLAG_MIN;
+ if (rs_packet->info & INFO_AUTO)
+ analog->mqflags |= SR_MQFLAG_AUTORANGE;
+
+ *floatval = rawval;
+ return SR_OK;
+}
projects / libsigrok.git / blobdiff