+/*
+ * This file is part of the sigrok 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/>.
+ */
+
+#include "protocol.h"
+#include <stdlib.h>
+#include <string.h>
+#include <math.h>
+
+/*
+ * Flags passed from the DMM.
+ */
+struct brymen_flags {
+ gboolean low_batt;
+ gboolean decibel, duty_cycle, hertz, amp, beep, ohm, fahrenheit;
+ gboolean celsius, capacitance, diode, volt, dc, ac;
+};
+
+struct bm850_command {
+ uint8_t dle;
+ uint8_t stx;
+ uint8_t cmd;
+ uint8_t arg[2];
+ uint8_t checksum;
+ uint8_t dle2;
+ uint8_t etx;
+};
+
+struct brymen_header {
+ uint8_t dle;
+ uint8_t stx;
+ uint8_t cmd;
+ uint8_t len;
+};
+
+struct brymen_tail {
+ uint8_t checksum;
+ uint8_t dle;
+ uint8_t etx;
+};
+
+/*
+ * We only have one command because we only support the BM-857. However, the
+ * driver is easily extensible to support more models, as the protocols are very
+ * similar.
+ */
+enum {
+ BM_CMD_REQUEST_READING = 0x00,
+};
+
+
+static int bm_send_command(uint8_t command, uint8_t arg1, uint8_t arg2,
+ struct sr_serial_dev_inst *serial)
+{
+ struct bm850_command cmdout = {
+ .dle = 0x10, .stx = 0x02,
+ .cmd = command,
+ .arg = {arg1, arg2},
+ .checksum = arg1^arg2, .dle2 = 0x10, .etx = 0x03};
+ int written;
+
+ /* TODO: How do we compute the checksum? Hardware seems to ignore it */
+
+ /* Request reading */
+ written = serial_write(serial, &cmdout, sizeof(cmdout));
+ if(written != sizeof(cmdout))
+ return SR_ERR;
+
+ return SR_OK;
+}
+
+SR_PRIV int brymen_packet_request(struct sr_serial_dev_inst *serial)
+{
+ return bm_send_command(BM_CMD_REQUEST_READING, 0, 0, serial);
+}
+
+SR_PRIV int brymen_packet_length(const uint8_t *buf, int *len)
+{
+ struct brymen_header *hdr;
+ const int brymen_max_packet_len = 22;
+ int packet_len;
+ const size_t buflen = *len;
+
+ hdr = (void*)buf;
+
+ /* Did we receive a complete header yet? */
+ if (buflen < sizeof(*hdr) )
+ return PACKET_NEED_MORE_DATA;
+
+ if (hdr->dle != 0x10 || hdr->stx != 0x02)
+ return PACKET_INVALID_HEADER;
+
+ /* Our packet includes the header, the payload, and the tail */
+ packet_len = sizeof(*hdr) + hdr->len + sizeof(struct brymen_tail);
+
+ /* In case we pick up an invalid header, limit our search */
+ if (packet_len > brymen_max_packet_len) {
+ sr_spew("Header specifies an invalid payload length: %i.",
+ hdr->len);
+ return PACKET_INVALID_HEADER;
+ }
+
+ *len = packet_len;
+ sr_spew("Expecting a %d-byte packet.", *len);
+ return PACKET_HEADER_OK;
+}
+
+SR_PRIV gboolean brymen_packet_is_valid(const uint8_t *buf)
+{
+ struct brymen_header *hdr;
+ struct brymen_tail *tail;
+ int i;
+ uint8_t chksum = 0;
+ const uint8_t *payload = buf + sizeof(struct brymen_header);
+
+ hdr = (void*)buf;
+ tail = (void*)(payload + hdr->len);
+
+ for (i = 0; i< hdr->len; i++)
+ chksum ^= payload[i];
+
+ if (tail->checksum != chksum) {
+ sr_dbg("Packet has invalid checksum 0x%.2x. Expected 0x%.2x",
+ chksum, tail->checksum);
+ return FALSE;
+ }
+
+ return TRUE;
+}
+
+static int parse_value(const char *strbuf, const int len, float *floatval)
+{
+ int s, d;
+ char str[32];
+
+ if (strstr(strbuf, "OL")) {
+ sr_dbg("Overlimit.");
+ *floatval = INFINITY;
+ return SR_OK;
+ }
+
+ memset(str, 0, sizeof(str));
+ /* Spaces may interfere with strtod parsing the exponent. Strip them */
+ for (s = 0, d = 0; s < len; s++)
+ if (strbuf[s] != ' ')
+ str[d++] = strbuf[s];
+ /* YES, it's that simple !*/
+ *floatval = strtod(str, NULL);
+
+ return SR_OK;
+}
+static void parse_flags(const uint8_t *buf, struct brymen_flags *info)
+{
+ const uint8_t * bfunc = buf + sizeof(struct brymen_header);
+
+ info->low_batt = (bfunc[3] & (1 << 7)) != 0;
+
+ info->decibel = (bfunc[1] & (1 << 5)) != 0;
+ info->duty_cycle = (bfunc[1] & (1 << 3)) != 0;
+ info->hertz = (bfunc[1] & (1 << 2)) != 0;
+ info->amp = (bfunc[1] & (1 << 1)) != 0;
+ info->beep = (bfunc[1] & (1 << 0)) != 0;
+
+ info->ohm = (bfunc[0] & (1 << 7)) != 0;
+ info->fahrenheit = (bfunc[0] & (1 << 6)) != 0;
+ info->celsius = (bfunc[0] & (1 << 5)) != 0;
+ info->diode = (bfunc[0] & (1 << 4)) != 0;
+ info->capacitance = (bfunc[0] & (1 << 3)) != 0;
+ info->volt = (bfunc[0] & (1 << 2)) != 0;
+ info->dc = (bfunc[0] & (1 << 1)) != 0;
+ info->ac = (bfunc[0] & (1 << 0)) != 0;
+}
+
+SR_PRIV int sr_brymen_parse(const uint8_t *buf, float *floatval,
+ struct sr_datafeed_analog *analog, void *info)
+{
+ struct brymen_flags flags;
+ struct brymen_header *hdr = (void*) buf;
+ const uint8_t *bfunc = buf + sizeof(struct brymen_header);
+ int asciilen;
+
+ (void)info;
+ analog->mqflags = 0;
+
+ /* Give some debug info about the package */
+ asciilen = hdr->len - 4;
+ sr_dbg("DMM flags: %.2x %.2x %.2x %.2x",
+ bfunc[3], bfunc[2], bfunc[1], bfunc[0]);
+ /* Value is an ASCII string */
+ sr_dbg("DMM packet: \"%.*s\"", asciilen, bfunc + 4);
+
+ parse_flags(buf, &flags);
+ parse_value((const char*)(bfunc + 4), asciilen, floatval);
+
+ if (flags.volt) {
+ analog->mq = SR_MQ_VOLTAGE;
+ analog->unit = SR_UNIT_VOLT;
+ }
+ if (flags.amp) {
+ analog->mq = SR_MQ_CURRENT;
+ analog->unit = SR_UNIT_AMPERE;
+ }
+ if (flags.ohm) {
+ if (flags.beep)
+ analog->mq = SR_MQ_CONTINUITY;
+ else
+ analog->mq = SR_MQ_RESISTANCE;
+ analog->unit = SR_UNIT_OHM;
+ }
+ if (flags.hertz) {
+ analog->mq = SR_MQ_FREQUENCY;
+ analog->unit = SR_UNIT_HERTZ;
+ }
+ if (flags.duty_cycle) {
+ analog->mq = SR_MQ_DUTY_CYCLE;
+ analog->unit = SR_UNIT_PERCENTAGE;
+ }
+ if (flags.capacitance) {
+ analog->mq = SR_MQ_CAPACITANCE;
+ analog->unit = SR_UNIT_FARAD;
+ }
+ if (flags.fahrenheit) {
+ analog->mq = SR_MQ_TEMPERATURE;
+ analog->unit = SR_UNIT_FAHRENHEIT;
+ }
+ if (flags.celsius) {
+ analog->mq = SR_MQ_TEMPERATURE;
+ analog->unit = SR_UNIT_CELSIUS;
+ }
+ if (flags.capacitance) {
+ analog->mq = SR_MQ_CAPACITANCE;
+ analog->unit = SR_UNIT_FARAD;
+ }
+ /*
+ * The high-end brymen models have a configurable reference impedance.
+ * When the reference impedance is changed, the DMM sends one packet
+ * with the value of the new reference impedance. Both decibel and ohm
+ * flags are set in this case, so we must be careful to correctly
+ * identify the value as ohm, not dBmW
+ */
+ if (flags.decibel && !flags.ohm) {
+ analog->mq = SR_MQ_POWER;
+ analog->unit = SR_UNIT_DECIBEL_MW;
+ /*
+ * For some reason, dBm measurements are sent by the multimeter
+ * with a value three orders of magnitude smaller than the
+ * displayed value.
+ * */
+ *floatval *= 1000;
+ }
+
+ if (flags.diode)
+ analog->mqflags |= SR_MQFLAG_DIODE;
+ /* We can have both AC+DC in a single measurement */
+ if (flags.ac)
+ analog->mqflags |= SR_MQFLAG_AC;
+ if (flags.dc)
+ analog->mqflags |= SR_MQFLAG_DC;
+
+ if (flags.low_batt)
+ sr_info("Low battery!");
+
+ return SR_OK;
+}
\ No newline at end of file