279 lines
7.0 KiB
C
279 lines
7.0 KiB
C
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/*
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* This file is part of the sigrok project.
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*
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* Copyright (C) 2012 Alexandru Gagniuc <mr.nuke.me@gmail.com>
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "protocol.h"
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#include <stdlib.h>
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#include <string.h>
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#include <math.h>
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/*
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* Flags passed from the DMM.
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*/
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struct brymen_flags {
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gboolean low_batt;
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gboolean decibel, duty_cycle, hertz, amp, beep, ohm, fahrenheit;
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gboolean celsius, capacitance, diode, volt, dc, ac;
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};
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struct bm850_command {
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uint8_t dle;
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uint8_t stx;
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uint8_t cmd;
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uint8_t arg[2];
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uint8_t checksum;
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uint8_t dle2;
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uint8_t etx;
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};
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struct brymen_header {
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uint8_t dle;
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uint8_t stx;
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uint8_t cmd;
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uint8_t len;
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};
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struct brymen_tail {
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uint8_t checksum;
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uint8_t dle;
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uint8_t etx;
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};
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/*
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* We only have one command because we only support the BM-857. However, the
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* driver is easily extensible to support more models, as the protocols are very
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* similar.
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*/
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enum {
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BM_CMD_REQUEST_READING = 0x00,
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};
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static int bm_send_command(uint8_t command, uint8_t arg1, uint8_t arg2,
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struct sr_serial_dev_inst *serial)
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{
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struct bm850_command cmdout = {
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.dle = 0x10, .stx = 0x02,
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.cmd = command,
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.arg = {arg1, arg2},
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.checksum = arg1^arg2, .dle2 = 0x10, .etx = 0x03};
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int written;
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/* TODO: How do we compute the checksum? Hardware seems to ignore it */
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/* Request reading */
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written = serial_write(serial, &cmdout, sizeof(cmdout));
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if(written != sizeof(cmdout))
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return SR_ERR;
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return SR_OK;
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}
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SR_PRIV int brymen_packet_request(struct sr_serial_dev_inst *serial)
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{
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return bm_send_command(BM_CMD_REQUEST_READING, 0, 0, serial);
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}
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SR_PRIV int brymen_packet_length(const uint8_t *buf, int *len)
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{
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struct brymen_header *hdr;
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const int brymen_max_packet_len = 22;
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int packet_len;
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const size_t buflen = *len;
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hdr = (void*)buf;
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/* Did we receive a complete header yet? */
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if (buflen < sizeof(*hdr) )
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return PACKET_NEED_MORE_DATA;
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if (hdr->dle != 0x10 || hdr->stx != 0x02)
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return PACKET_INVALID_HEADER;
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/* Our packet includes the header, the payload, and the tail */
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packet_len = sizeof(*hdr) + hdr->len + sizeof(struct brymen_tail);
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/* In case we pick up an invalid header, limit our search */
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if (packet_len > brymen_max_packet_len) {
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sr_spew("Header specifies an invalid payload length: %i.",
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hdr->len);
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return PACKET_INVALID_HEADER;
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}
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*len = packet_len;
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sr_spew("Expecting a %d-byte packet.", *len);
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return PACKET_HEADER_OK;
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}
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SR_PRIV gboolean brymen_packet_is_valid(const uint8_t *buf)
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{
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struct brymen_header *hdr;
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struct brymen_tail *tail;
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int i;
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uint8_t chksum = 0;
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const uint8_t *payload = buf + sizeof(struct brymen_header);
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hdr = (void*)buf;
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tail = (void*)(payload + hdr->len);
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for (i = 0; i< hdr->len; i++)
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chksum ^= payload[i];
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if (tail->checksum != chksum) {
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sr_dbg("Packet has invalid checksum 0x%.2x. Expected 0x%.2x",
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chksum, tail->checksum);
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return FALSE;
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}
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return TRUE;
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}
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static int parse_value(const char *strbuf, const int len, float *floatval)
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{
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int s, d;
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char str[32];
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if (strstr(strbuf, "OL")) {
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sr_dbg("Overlimit.");
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*floatval = INFINITY;
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return SR_OK;
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}
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memset(str, 0, sizeof(str));
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/* Spaces may interfere with strtod parsing the exponent. Strip them */
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for (s = 0, d = 0; s < len; s++)
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if (strbuf[s] != ' ')
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str[d++] = strbuf[s];
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/* YES, it's that simple !*/
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*floatval = strtod(str, NULL);
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return SR_OK;
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}
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static void parse_flags(const uint8_t *buf, struct brymen_flags *info)
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{
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const uint8_t * bfunc = buf + sizeof(struct brymen_header);
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info->low_batt = (bfunc[3] & (1 << 7)) != 0;
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info->decibel = (bfunc[1] & (1 << 5)) != 0;
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info->duty_cycle = (bfunc[1] & (1 << 3)) != 0;
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info->hertz = (bfunc[1] & (1 << 2)) != 0;
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info->amp = (bfunc[1] & (1 << 1)) != 0;
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info->beep = (bfunc[1] & (1 << 0)) != 0;
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info->ohm = (bfunc[0] & (1 << 7)) != 0;
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info->fahrenheit = (bfunc[0] & (1 << 6)) != 0;
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info->celsius = (bfunc[0] & (1 << 5)) != 0;
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info->diode = (bfunc[0] & (1 << 4)) != 0;
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info->capacitance = (bfunc[0] & (1 << 3)) != 0;
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info->volt = (bfunc[0] & (1 << 2)) != 0;
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info->dc = (bfunc[0] & (1 << 1)) != 0;
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info->ac = (bfunc[0] & (1 << 0)) != 0;
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}
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SR_PRIV int sr_brymen_parse(const uint8_t *buf, float *floatval,
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struct sr_datafeed_analog *analog, void *info)
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{
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struct brymen_flags flags;
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struct brymen_header *hdr = (void*) buf;
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const uint8_t *bfunc = buf + sizeof(struct brymen_header);
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int asciilen;
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(void)info;
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analog->mqflags = 0;
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/* Give some debug info about the package */
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asciilen = hdr->len - 4;
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sr_dbg("DMM flags: %.2x %.2x %.2x %.2x",
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bfunc[3], bfunc[2], bfunc[1], bfunc[0]);
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/* Value is an ASCII string */
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sr_dbg("DMM packet: \"%.*s\"", asciilen, bfunc + 4);
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parse_flags(buf, &flags);
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parse_value((const char*)(bfunc + 4), asciilen, floatval);
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if (flags.volt) {
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analog->mq = SR_MQ_VOLTAGE;
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analog->unit = SR_UNIT_VOLT;
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}
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if (flags.amp) {
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analog->mq = SR_MQ_CURRENT;
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analog->unit = SR_UNIT_AMPERE;
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}
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if (flags.ohm) {
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if (flags.beep)
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analog->mq = SR_MQ_CONTINUITY;
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else
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analog->mq = SR_MQ_RESISTANCE;
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analog->unit = SR_UNIT_OHM;
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}
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if (flags.hertz) {
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analog->mq = SR_MQ_FREQUENCY;
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analog->unit = SR_UNIT_HERTZ;
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}
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if (flags.duty_cycle) {
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analog->mq = SR_MQ_DUTY_CYCLE;
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analog->unit = SR_UNIT_PERCENTAGE;
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}
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if (flags.capacitance) {
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analog->mq = SR_MQ_CAPACITANCE;
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analog->unit = SR_UNIT_FARAD;
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}
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if (flags.fahrenheit) {
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analog->mq = SR_MQ_TEMPERATURE;
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analog->unit = SR_UNIT_FAHRENHEIT;
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}
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if (flags.celsius) {
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analog->mq = SR_MQ_TEMPERATURE;
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analog->unit = SR_UNIT_CELSIUS;
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}
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if (flags.capacitance) {
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analog->mq = SR_MQ_CAPACITANCE;
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analog->unit = SR_UNIT_FARAD;
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}
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/*
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* The high-end brymen models have a configurable reference impedance.
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* When the reference impedance is changed, the DMM sends one packet
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* with the value of the new reference impedance. Both decibel and ohm
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* flags are set in this case, so we must be careful to correctly
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* identify the value as ohm, not dBmW
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*/
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if (flags.decibel && !flags.ohm) {
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analog->mq = SR_MQ_POWER;
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analog->unit = SR_UNIT_DECIBEL_MW;
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/*
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* For some reason, dBm measurements are sent by the multimeter
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* with a value three orders of magnitude smaller than the
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* displayed value.
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* */
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*floatval *= 1000;
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}
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if (flags.diode)
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analog->mqflags |= SR_MQFLAG_DIODE;
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/* We can have both AC+DC in a single measurement */
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if (flags.ac)
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analog->mqflags |= SR_MQFLAG_AC;
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if (flags.dc)
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analog->mqflags |= SR_MQFLAG_DC;
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if (flags.low_batt)
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sr_info("Low battery!");
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return SR_OK;
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}
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