victor-dmm: add protocol decoder

hardware/victor-dmm/api.c

@@ -322,10 +322,8 @@ static void receive_transfer(struct libusb_transfer *transfer)
 		hw_dev_acquisition_stop(sdi, sdi);
 	} else if (transfer->status == LIBUSB_TRANSFER_COMPLETED) {
 		sr_dbg("got %d-byte packet", transfer->actual_length);
-		if (transfer->actual_length == 14) {
+		if (transfer->actual_length == DMM_DATA_SIZE) {
-			devc->num_samples++;
+			victor_dmm_receive_data(sdi, transfer->buffer);
-			/* TODO */
-
 			if (devc->limit_samples) {
 				if (devc->num_samples >= devc->limit_samples)
 					hw_dev_acquisition_stop(sdi, sdi);
@@ -434,14 +432,14 @@ static int hw_dev_acquisition_start(const struct sr_dev_inst *sdi,
 	}
 	devc->usbfd[i] = -1;
 
-	buf = g_try_malloc(14);
+	buf = g_try_malloc(DMM_DATA_SIZE);
 	transfer = libusb_alloc_transfer(0);
 	/* Each transfer request gets 100ms to arrive before it's restarted.
 	 * The device only sends 1 transfer/second no matter how many
 	 * times you ask, but we want to keep step with the USB events
 	 * handling above. */
 	libusb_fill_interrupt_transfer(transfer, devc->usb->devhdl,
-			VICTOR_ENDPOINT, buf, 14, receive_transfer, cb_data, 100);
+			VICTOR_ENDPOINT, buf, DMM_DATA_SIZE, receive_transfer, cb_data, 100);
 	if ((ret = libusb_submit_transfer(transfer) != 0)) {
 		sr_err("unable to submit transfer: %s", libusb_error_name(ret));
 		libusb_free_transfer(transfer);

hardware/victor-dmm/protocol.c

@@ -17,26 +17,279 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include <stdlib.h>
 #include <glib.h>
 #include "libsigrok.h"
 #include "libsigrok-internal.h"
 #include "protocol.h"
+#include <string.h>
+#include <math.h>
 
-SR_PRIV int victor_dmm_receive_data(int fd, int revents, void *cb_data)
+
+/* Reverse the high nibble into the low nibble */
+static uint8_t decode_digit(uint8_t in)
 {
-	const struct sr_dev_inst *sdi;
+	uint8_t out, i;
-	struct dev_context *devc;
 
-	if (!(sdi = cb_data))
+	out = 0;
-		return TRUE;
+	in >>= 4;
-
+	for (i = 0x08; i; i >>= 1) {
-	if (!(devc = sdi->priv))
+		out >>= 1;
-		return TRUE;
+		if (in & i)
-
+			out |= 0x08;
-	if (revents == G_IO_IN) {
-		/* TODO */
 	}
 
-	return TRUE;
+	return out;
 }
+
+static void decode_buf(struct dev_context *devc, unsigned char *data)
+{
+	struct sr_datafeed_packet packet;
+	struct sr_datafeed_analog analog;
+	long factor, ivalue;
+	uint8_t digits[4];
+	gboolean is_duty, is_continuity, is_diode, is_ac, is_dc, is_auto;
+	gboolean is_hold, is_max, is_min, is_relative, minus;
+	float fvalue;
+
+	digits[0] = decode_digit(data[12]);
+	digits[1] = decode_digit(data[11]);
+	digits[2] = decode_digit(data[10]);
+	digits[3] = decode_digit(data[9]);
+
+	if (digits[0] == 0x0f && digits[1] == 0x00 && digits[2] == 0x0a &&
+			digits[3] == 0x0f)
+		/* The "over limit" (OL) display comes through like this */
+		ivalue = -1;
+	else if (digits[0] > 9 || digits[1] > 9 || digits[2] > 9 || digits[3] > 9)
+		/* An invalid digit in any position denotes no value. */
+		ivalue = -2;
+	else {
+		ivalue = digits[0] * 1000;
+		ivalue += digits[1] * 100;
+		ivalue += digits[2] * 10;
+		ivalue += digits[3];
+	}
+
+	/* Decimal point position */
+	switch (data[7] >> 4) {
+	case 0x00:
+		factor = 0;
+		break;
+	case 0x02:
+		factor = 1;
+		break;
+	case 0x04:
+		factor = 2;
+		break;
+	case 0x08:
+		factor = 3;
+		break;
+	default:
+		sr_err("Unknown decimal point value %.2x.", data[7]);
+	}
+
+	/* Minus flag */
+	minus = data[2] & 0x01;
+
+	/* Mode detail symbols on the right side of the digits */
+	is_duty = is_continuity = is_diode = FALSE;
+	switch (data[4]) {
+	case 0x00:
+		/* None. */
+		break;
+	case 0x01:
+		/* Micro */
+		factor += 6;
+		break;
+	case 0x02:
+		/* Milli */
+		factor += 3;
+		break;
+	case 0x04:
+		/* Kilo */
+		ivalue *= 1000;
+		break;
+	case 0x08:
+		/* Mega */
+		ivalue *= 1000000;
+		break;
+	case 0x10:
+		/* Continuity shows up as Ohm + this bit */
+		is_continuity = TRUE;
+		break;
+	case 0x20:
+		/* Diode tester is Volt + this bit */
+		is_diode = TRUE;
+		break;
+	case 0x40:
+		is_duty = TRUE;
+		break;
+	case 0x80:
+		/* Never seen */
+		sr_dbg("Unknown mode right detail %.2x.", data[4]);
+		break;
+	default:
+		sr_dbg("Unknown/invalid mode right detail %.2x.", data[4]);
+	}
+
+	/* Scale flags on the right, continued */
+	is_max = is_min = TRUE;
+	if (data[5] & 0x04)
+		is_max = TRUE;
+	if (data[5] & 0x08)
+		is_min = TRUE;
+	if (data[5] & 0x40)
+		/* Nano */
+		factor += 9;
+
+	/* Mode detail symbols on the left side of the digits */
+	is_auto = is_dc = is_ac = is_hold = is_relative = FALSE;
+	if (data[6] & 0x04)
+		is_auto = TRUE;
+	if (data[6] & 0x08)
+		is_dc = TRUE;
+	if (data[6] & 0x10)
+		is_ac = TRUE;
+	if (data[6] & 0x20)
+		is_relative = TRUE;
+	if (data[6] & 0x40)
+		is_hold = TRUE;
+
+	fvalue = (float)ivalue / pow(10, factor);
+	if (minus)
+		fvalue = -fvalue;
+
+	memset(&analog, 0, sizeof(struct sr_datafeed_analog));
+
+	/* Measurement mode */
+	analog.mq = -1;
+	switch (data[3]) {
+	case 0x00:
+		if (is_duty) {
+			analog.mq = SR_MQ_DUTY_CYCLE;
+			analog.unit = SR_UNIT_PERCENTAGE;
+		} else
+			sr_dbg("Unknown measurement mode %.2x.", data[3]);
+		break;
+	case 0x01:
+		if (is_diode) {
+			analog.mq = SR_MQ_VOLTAGE;
+			analog.unit = SR_UNIT_VOLT;
+			analog.mqflags |= SR_MQFLAG_DIODE;
+			if (ivalue < 0)
+				fvalue = NAN;
+		} else {
+			if (ivalue < 0)
+				break;
+			analog.mq = SR_MQ_VOLTAGE;
+			analog.unit = SR_UNIT_VOLT;
+			if (is_ac)
+				analog.mqflags |= SR_MQFLAG_AC;
+			if (is_dc)
+				analog.mqflags |= SR_MQFLAG_DC;
+		}
+		break;
+	case 0x02:
+		analog.mq = SR_MQ_CURRENT;
+		analog.unit = SR_UNIT_AMPERE;
+		if (is_ac)
+			analog.mqflags |= SR_MQFLAG_AC;
+		if (is_dc)
+			analog.mqflags |= SR_MQFLAG_DC;
+		break;
+	case 0x04:
+		if (is_continuity) {
+			analog.mq = SR_MQ_CONTINUITY;
+			analog.unit = SR_UNIT_BOOLEAN;
+			fvalue = ivalue < 0 ? 0.0 : 1.0;
+		} else {
+			analog.mq = SR_MQ_RESISTANCE;
+			analog.unit = SR_UNIT_OHM;
+			if (ivalue < 0)
+				fvalue = INFINITY;
+		}
+		break;
+	case 0x08:
+		/* Never seen */
+		sr_dbg("Unknown measurement mode %.2x.", data[3]);
+		break;
+	case 0x10:
+		analog.mq = SR_MQ_FREQUENCY;
+		analog.unit = SR_UNIT_HERTZ;
+		break;
+	case 0x20:
+		analog.mq = SR_MQ_CAPACITANCE;
+		analog.unit = SR_UNIT_FARAD;
+		break;
+	case 0x40:
+		analog.mq = SR_MQ_TEMPERATURE;
+		analog.unit = SR_UNIT_CELSIUS;
+		break;
+	case 0x80:
+		analog.mq = SR_MQ_TEMPERATURE;
+		analog.unit = SR_UNIT_FAHRENHEIT;
+		break;
+	default:
+		sr_dbg("Unknown/invalid measurement mode %.2x.", data[3]);
+	}
+	if (analog.mq == -1)
+		return;
+
+	if (is_auto)
+		analog.mqflags |= SR_MQFLAG_AUTORANGE;
+	if (is_hold)
+		analog.mqflags |= SR_MQFLAG_HOLD;
+	if (is_max)
+		analog.mqflags |= SR_MQFLAG_MAX;
+	if (is_min)
+		analog.mqflags |= SR_MQFLAG_MIN;
+	if (is_relative)
+		analog.mqflags |= SR_MQFLAG_RELATIVE;
+
+	analog.num_samples = 1;
+	analog.data = &fvalue;
+	packet.type = SR_DF_ANALOG;
+	packet.payload = &analog;
+	sr_session_send(devc->cb_data, &packet);
+
+	devc->num_samples++;
+}
+
+SR_PRIV int victor_dmm_receive_data(struct sr_dev_inst *sdi, unsigned char *buf)
+{
+	struct dev_context *devc;
+	GString *dbg;
+	int i;
+	unsigned char data[DMM_DATA_SIZE];
+	unsigned char obfuscation[DMM_DATA_SIZE] = "jodenxunickxia";
+	unsigned char shuffle[DMM_DATA_SIZE] = {
+		6, 13, 5, 11, 2, 7, 9, 8, 3, 10, 12, 0, 4, 1
+	};
+
+	devc = sdi->priv;
+
+	for (i = 0; i < DMM_DATA_SIZE && buf[i] == 0; i++);
+	if (i == DMM_DATA_SIZE) {
+		/* This DMM outputs all zeroes from time to time, just ignore it. */
+		sr_dbg("Received all zeroes.");
+		return SR_OK;
+	}
+
+	/* Deobfuscate and reorder data. */
+	for (i = 0; i < DMM_DATA_SIZE; i++)
+		data[shuffle[i]] = (buf[i] - obfuscation[i]) & 0xff;
+
+	if (sr_log_loglevel_get() >= SR_LOG_SPEW) {
+		dbg = g_string_sized_new(128);
+		g_string_printf(dbg, "Deobfuscated.");
+		for (i = 0; i < DMM_DATA_SIZE; i++)
+			g_string_append_printf(dbg, " %.2x", data[i]);
+		sr_spew("%s", dbg->str);
+		g_string_free(dbg, TRUE);
+	}
+
+	decode_buf(devc, data);
+
+	return SR_OK;
+}
+

hardware/victor-dmm/protocol.h

@@ -33,6 +33,8 @@
 #define sr_warn(s, args...) sr_warn(DRIVER_LOG_DOMAIN s, ## args)
 #define sr_err(s, args...) sr_err(DRIVER_LOG_DOMAIN s, ## args)
 
+#define DMM_DATA_SIZE 14
+
 /** Private, per-device-instance driver context. */
 struct dev_context {
 	/** The current sampling limit (in number of samples). */
@@ -53,6 +55,6 @@ struct dev_context {
 	int usbfd[10];
 };
 
-SR_PRIV int victor_dmm_receive_data(int fd, int revents, void *cb_data);
+SR_PRIV int victor_dmm_receive_data(struct sr_dev_inst *sdi, unsigned char *buf);
 
 #endif