Merge pull request #936 from PX4/gps_logging

GPS Satellite SNR logging

src/modules/sdlog2/sdlog2.c

@@ -684,7 +684,7 @@ int sdlog2_thread_main(int argc, char *argv[])
 		case 'r': {
 				unsigned long r = strtoul(optarg, NULL, 10);
 
-				if (r <= 0) {
+				if (r == 0) {
 					r = 1;
 				}
 
@@ -834,6 +834,8 @@ int sdlog2_thread_main(int argc, char *argv[])
 			struct log_ESTM_s log_ESTM;
 			struct log_PWR_s log_PWR;
 			struct log_VICN_s log_VICN;
+			struct log_GSN0_s log_GSN0;
+			struct log_GSN1_s log_GSN1;
 		} body;
 	} log_msg = {
 		LOG_PACKET_HEADER_INIT(0)
@@ -982,6 +984,18 @@ int sdlog2_thread_main(int argc, char *argv[])
 			log_msg.body.log_GPS.vel_d = buf_gps_pos.vel_d_m_s;
 			log_msg.body.log_GPS.cog = buf_gps_pos.cog_rad;
 			LOGBUFFER_WRITE_AND_COUNT(GPS);
+
+			/* log the SNR of each satellite for a detailed view of signal quality */
+			log_msg.msg_type = LOG_GSN0_MSG;
+			/* pick the smaller number so we do not overflow any of the arrays */
+			unsigned gps_msg_max_snr = sizeof(buf_gps_pos.satellite_snr) / sizeof(buf_gps_pos.satellite_snr[0]);
+			unsigned log_max_snr = sizeof(log_msg.body.log_GSN0.satellite_snr) / sizeof(log_msg.body.log_GSN0.satellite_snr[0]);
+			unsigned sat_max_snr = (gps_msg_max_snr < log_max_snr) ? gps_msg_max_snr : log_max_snr;
+
+			for (unsigned i = 0; i < sat_max_snr; i++) {
+				log_msg.body.log_GSN0.satellite_snr[i] = buf_gps_pos.satellite_snr[i];
+			}
+			LOGBUFFER_WRITE_AND_COUNT(GSN0);
 		}
 
 		/* --- SENSOR COMBINED --- */

src/modules/sdlog2/sdlog2_messages.h

@@ -317,6 +317,18 @@ struct log_VICN_s {
 	float yaw;
 };
 
+/* --- GSN0 - GPS SNR #0 --- */
+#define LOG_GSN0_MSG 26
+struct log_GSN0_s {
+	uint8_t satellite_snr[16];			/**< Signal to noise ratio of satellite. 0 for none, 255 for max. */
+};
+
+/* --- GSN1 - GPS SNR #1 --- */
+#define LOG_GSN1_MSG 27
+struct log_GSN1_s {
+	uint8_t satellite_snr[16];			/**< Signal to noise ratio of satellite. 0 for none, 255 for max. */
+};
+
 /********** SYSTEM MESSAGES, ID > 0x80 **********/
 
 /* --- TIME - TIME STAMP --- */
@@ -368,6 +380,8 @@ static const struct log_format_s log_formats[] = {
 	LOG_FORMAT(ESTM, "ffffffffffBBBB",	"s0,s1,s2,s3,s4,s5,s6,s7,s8,s9,nStat,statNaN,covNaN,kGainNaN"),
 	LOG_FORMAT(PWR, "fffBBBBB",		"Periph5V,Servo5V,RSSI,UsbOk,BrickOk,ServoOk,PeriphOC,HipwrOC"),
 	LOG_FORMAT(VICN, "ffffff",		"X,Y,Z,Roll,Pitch,Yaw"),
+	LOG_FORMAT(GSN0, "BBBBBBBBBBBBBBBB",	"s0,s1,s2,s3,s4,s5,s6,s7,s8,s9,s10,s11,s12,s13,s14,s15"),
+	LOG_FORMAT(GSN1, "BBBBBBBBBBBBBBBB",	"s0,s1,s2,s3,s4,s5,s6,s7,s8,s9,s10,s11,s12,s13,s14,s15"),
 
 	/* system-level messages, ID >= 0x80 */
 	/* FMT: don't write format of format message, it's useless */