X-Git-Url: http://sigrok.org/gitweb/?a=blobdiff_plain;f=src%2Fdmm%2Fbm86x.c;h=ea260d8f97180869cfa6441696be549a476323da;hb=81ceb6a51dd666987fb5c67b83c5ba14d105b301;hp=318d4af011c9af61d56e5253fb6e3f13259cf824;hpb=0759e2f55b5e45ff283f396c38c08eb180ba83b7;p=libsigrok.git

diff --git a/src/dmm/bm86x.c b/src/dmm/bm86x.c
index 318d4af0..ea260d8f 100644
--- a/src/dmm/bm86x.c
+++ b/src/dmm/bm86x.c
@@ -41,7 +41,6 @@ SR_PRIV int sr_brymen_bm86x_packet_request(struct sr_serial_dev_inst *serial)
 {
 	static const uint8_t request[] = { 0x00, 0x00, 0x86, 0x66, };
 
-	sr_spew("%s() sending request", __func__);
 	serial_write_nonblocking(serial, request, sizeof(request));
 
 	return SR_OK;
@@ -50,14 +49,6 @@ SR_PRIV int sr_brymen_bm86x_packet_request(struct sr_serial_dev_inst *serial)
 
 SR_PRIV gboolean sr_brymen_bm86x_packet_valid(const uint8_t *buf)
 {
-	GString *text;
-
-	if (sr_log_loglevel_get() >= SR_LOG_SPEW) {
-		text = sr_hexdump_new(buf, BRYMEN_BM86X_PACKET_SIZE);
-		sr_spew("%s() checking DMM packet: %s", __func__, text->str);
-		sr_hexdump_free(text);
-	}
-
 	/*
 	 * "Model ID3" (3rd HID report, byte 3) is the only documented
 	 * fixed value, and must be 0x86. All other positions either depend
@@ -68,6 +59,22 @@ SR_PRIV gboolean sr_brymen_bm86x_packet_valid(const uint8_t *buf)
 	if (buf[19] != 0x86)
 		return FALSE;
 
+	/*
+	 * 2021-05 update: The devices that we have seen in the field do
+	 * provide four bytes which we can synchronize to. Which happens
+	 * to match the bm52x and bm82x devices' protocol. This condition
+	 * is not documented by the vendor, but improves reliability of
+	 * the re-synchronization for slight offsets, which were seen
+	 * in the field, and which would have kept failing in an earlier
+	 * implementation.
+	 */
+	if (buf[16] != 0x86)
+		return FALSE;
+	if (buf[17] != 0x86)
+		return FALSE;
+	if (buf[18] != 0x86)
+		return FALSE;
+
 	return TRUE;
 }
 
@@ -172,6 +179,7 @@ static void brymen_bm86x_parse(const uint8_t *buf, float *floatval,
 	int ret, digits, is_diode, over_limit, scale;
 	uint8_t ind1, ind15;
 
+	temp_unit = '\0';
 	if (ch_idx == 0) {
 		/*
 		 * Main display. Note that _some_ of the second display's
@@ -220,7 +228,7 @@ static void brymen_bm86x_parse(const uint8_t *buf, float *floatval,
 		} else if (buf[15] & 0x80) {
 			analog->meaning->mq = SR_MQ_DUTY_CYCLE;
 			analog->meaning->unit = SR_UNIT_PERCENTAGE;
-		} else if (buf[ 2] & 0x0a) {
+		} else if ((buf[2] & 0x0a) && temp_unit) {
 			analog->meaning->mq = SR_MQ_TEMPERATURE;
 			if (temp_unit == 'F')
 				analog->meaning->unit = SR_UNIT_FAHRENHEIT;
@@ -286,9 +294,14 @@ static void brymen_bm86x_parse(const uint8_t *buf, float *floatval,
 		analog->encoding->digits  = digits;
 		analog->spec->spec_digits = digits;
 	} else if (ch_idx == 1) {
-		/* Secondary display. */
+		/*
+		 * Secondary display. Also inspect _some_ primary display
+		 * data, to determine the secondary display's validity.
+		 */
+		(void)brymen_bm86x_parse_digits(&buf[2], 6, txtbuf,
+			NULL, &temp_unit, NULL, 0x80);
 		ret = brymen_bm86x_parse_digits(&buf[9], 4, txtbuf,
-			floatval, &temp_unit, &digits, 0x10);
+			floatval, NULL, &digits, 0x10);
 
 		/* SI unit. */
 		if (buf[14] & 0x08) {
@@ -303,7 +316,7 @@ static void brymen_bm86x_parse(const uint8_t *buf, float *floatval,
 		} else if (buf[14] & 0x04) {
 			analog->meaning->mq = SR_MQ_FREQUENCY;
 			analog->meaning->unit = SR_UNIT_HERTZ;
-		} else if (buf[9] & 0x40) {
+		} else if ((buf[9] & 0x40) && temp_unit) {
 			analog->meaning->mq = SR_MQ_TEMPERATURE;
 			if (temp_unit == 'F')
 				analog->meaning->unit = SR_UNIT_FAHRENHEIT;