X-Git-Url: https://sigrok.org/gitweb/?a=blobdiff_plain;f=src%2Fdmm%2Fbm86x.c;h=c160a88c033fc452b0e740a94d196700ba81818d;hb=HEAD;hp=3cfe586db7bdb978b4be29ddf4de8e36c5330f81;hpb=3775ef8c7a582898fb297eeb6df44f9f3995dd50;p=libsigrok.git

diff --git a/src/dmm/bm86x.c b/src/dmm/bm86x.c
index 3cfe586d..c160a88c 100644
--- a/src/dmm/bm86x.c
+++ b/src/dmm/bm86x.c
@@ -23,9 +23,10 @@
  *
  * Brymen BM86x serial protocol parser. The USB protocol (for the cable)
  * and the packet description (for the meter) were retrieved from:
- * http://brymen.com/product-html/Download2.html
- * http://brymen.com/product-html/PD02BM860s_protocolDL.html
- * http://brymen.com/product-html/images/DownloadList/ProtocolList/BM860-BM860s_List/BM860-BM860s-500000-count-dual-display-DMMs-protocol.pdf
+ * http://www.brymen.com/Download2.html
+ * http://www.brymen.com/PD02BM860s_protocolDL.html
+ * http://www.brymen.com/images/DownloadList/ProtocolList/BM860-BM860s_List/BM860-BM860s-500000-count-dual-display-DMMs-protocol.pdf
+ * http://web.archive.org/web/20191231053213/http://www.brymen.com/images/DownloadList/ProtocolList/BM860-BM860s_List/BM860-BM860s-500000-count-dual-display-DMMs-protocol.pdf
  */
 
 #include <config.h>
@@ -41,7 +42,6 @@ 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;
@@ -60,6 +60,22 @@ 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;
 }
 
@@ -164,6 +180,7 @@ 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
@@ -212,7 +229,7 @@ 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;
@@ -278,9 +295,16 @@ 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);
+		if (ret != SR_OK)
+			return;
 
 		/* SI unit. */
 		if (buf[14] & 0x08) {
@@ -295,7 +319,7 @@ 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;