libsigrok/hardware/common/dmm/rs9lcd.c

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/*
2013-04-23 20:24:30 +00:00
* 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;
}