Add MavlinkStreamGPSStatus status class stream via GPS_STATUS.hpp and add PRN code to satellite_info.msg.

msg/satellite_info.msg

@@ -1,9 +1,10 @@
 uint64 timestamp		# time since system start (microseconds)
 uint8 SAT_INFO_MAX_SATELLITES = 20
 
-uint8 count			# Number of satellites in satellite info
+uint8 count			# Number of satellites visible to the receiver
 uint8[20] svid	 		# Space vehicle ID [1..255], see scheme below
 uint8[20] used			# 0: Satellite not used, 1: used for navigation
 uint8[20] elevation		# Elevation (0: right on top of receiver, 90: on the horizon) of satellite
 uint8[20] azimuth		# Direction of satellite, 0: 0 deg, 255: 360 deg.
 uint8[20] snr			# dBHz, Signal to noise ratio of satellite C/N0, range 0..99, zero when not tracking this satellite.
+uint8[20] prn                   # Satellite PRN code assignment, (psuedorandom number SBAS, valid codes are 120-144)

src/drivers/gps/definitions.h

@@ -41,8 +41,8 @@
 
 #include <drivers/drv_hrt.h>
 #include <px4_platform_common/defines.h>
-#include <uORB/topics/sensor_gps.h>
 #include <uORB/topics/satellite_info.h>
+#include <uORB/topics/sensor_gps.h>
 
 #define GPS_INFO(...) PX4_INFO(__VA_ARGS__)
 #define GPS_WARN(...) PX4_WARN(__VA_ARGS__)

src/drivers/gps/gps.cpp

@@ -83,7 +83,7 @@ typedef enum {
 
 /* struct for dynamic allocation of satellite info data */
 struct GPS_Sat_Info {
-	struct satellite_info_s 	_data;
+	satellite_info_s _data;
 };
 
 static constexpr int TASK_STACK_SIZE = 1760;

src/modules/mavlink/mavlink_main.cpp

@@ -1582,6 +1582,7 @@ Mavlink::configure_streams_to_default(const char *configure_single_stream)
 		configure_stream_local("GLOBAL_POSITION_INT", 5.0f);
 		configure_stream_local("GPS2_RAW", 1.0f);
 		configure_stream_local("GPS_RAW_INT", 1.0f);
+		configure_stream_local("GPS_STATUS", 1.0f);
 		configure_stream_local("HOME_POSITION", 0.5f);
 		configure_stream_local("LOCAL_POSITION_NED", 1.0f);
 		configure_stream_local("NAMED_VALUE_FLOAT", 1.0f);
@@ -1632,6 +1633,7 @@ Mavlink::configure_streams_to_default(const char *configure_single_stream)
 		configure_stream_local("GLOBAL_POSITION_INT", 50.0f);
 		configure_stream_local("GPS2_RAW", unlimited_rate);
 		configure_stream_local("GPS_RAW_INT", unlimited_rate);
+		configure_stream_local("GPS_STATUS", 1.0f);
 		configure_stream_local("HOME_POSITION", 0.5f);
 		configure_stream_local("NAMED_VALUE_FLOAT", 10.0f);
 		configure_stream_local("NAV_CONTROLLER_OUTPUT", 10.0f);
@@ -1754,6 +1756,7 @@ Mavlink::configure_streams_to_default(const char *configure_single_stream)
 		configure_stream_local("GLOBAL_POSITION_INT", 10.0f);
 		configure_stream_local("GPS2_RAW", unlimited_rate);
 		configure_stream_local("GPS_RAW_INT", unlimited_rate);
+		configure_stream_local("GPS_STATUS", 1.0f);
 		configure_stream_local("HIGHRES_IMU", 50.0f);
 		configure_stream_local("HOME_POSITION", 0.5f);
 		configure_stream_local("MANUAL_CONTROL", 5.0f);

src/modules/mavlink/mavlink_messages.cpp

@@ -118,6 +118,7 @@ using matrix::wrap_2pi;
 #include "streams/ESC_STATUS.hpp"
 #include "streams/EXTENDED_SYS_STATE.hpp"
 #include "streams/FLIGHT_INFORMATION.hpp"
+#include "streams/GPS_STATUS.hpp"
 #include "streams/HIGH_LATENCY2.hpp"
 #include "streams/HIL_STATE_QUATERNION.hpp"
 #include "streams/OBSTACLE_DISTANCE.hpp"
@@ -1761,7 +1762,6 @@ protected:
 	}
 };
 
-
 class MavlinkStreamGPSRawInt : public MavlinkStream
 {
 public:
@@ -5021,6 +5021,9 @@ static const StreamListItem streams_list[] = {
 #if defined(FLIGHT_INFORMATION_HPP)
 	create_stream_list_item<MavlinkStreamFlightInformation>(),
 #endif // FLIGHT_INFORMATION_HPP
+#if defined(GPS_STATUS_HPP)
+	create_stream_list_item<MavlinkStreamGPSStatus>(),
+#endif // GPS_STATUS_HPP
 #if defined(STORAGE_INFORMATION_HPP)
 	create_stream_list_item<MavlinkStreamStorageInformation>(),
 #endif // STORAGE_INFORMATION_HPP

src/modules/mavlink/mavlink_messages.h

@@ -67,7 +67,9 @@ static StreamListItem create_stream_list_item()
 }
 
 const char *get_stream_name(const uint16_t msg_id);
+
 MavlinkStream *create_mavlink_stream(const char *stream_name, Mavlink *mavlink);
+
 MavlinkStream *create_mavlink_stream(const uint16_t msg_id, Mavlink *mavlink);
 
 void get_mavlink_navigation_mode(const struct vehicle_status_s *const status, uint8_t *mavlink_base_mode,

src/modules/mavlink/streams/GPS_STATUS.hpp

@@ -0,0 +1,97 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2020 PX4 Development Team. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+#ifndef GPS_STATUS_HPP
+#define GPS_STATUS_HPP
+
+#include <uORB/topics/satellite_info.h>
+
+class MavlinkStreamGPSStatus : public MavlinkStream
+{
+public:
+	const char *get_name() const override { return MavlinkStreamGPSStatus::get_name_static(); }
+
+	static constexpr const char *get_name_static() { return "GPS_STATUS"; }
+
+	static constexpr uint16_t get_id_static() { return MAVLINK_MSG_ID_GPS_STATUS; }
+
+	uint16_t get_id() override { return get_id_static(); }
+
+	static MavlinkStream *new_instance(Mavlink *mavlink) { return new MavlinkStreamGPSStatus(mavlink); }
+
+	unsigned get_size() override
+	{
+		return _satellite_info_sub.advertised() ? MAVLINK_MSG_ID_GPS_STATUS_LEN + MAVLINK_NUM_NON_PAYLOAD_BYTES : 0;
+	}
+
+private:
+	uORB::Subscription _satellite_info_sub{ORB_ID(satellite_info)};
+
+	// Disallow copy and move construction.
+	MavlinkStreamGPSStatus(MavlinkStreamGPSStatus &) = delete;
+	MavlinkStreamGPSStatus &operator = (const MavlinkStreamGPSStatus &) = delete;
+
+protected:
+	explicit MavlinkStreamGPSStatus(Mavlink *mavlink) : MavlinkStream(mavlink)
+	{}
+
+	bool send() override
+	{
+		satellite_info_s sat {};
+
+		if (_satellite_info_sub.update(&sat)) {
+			mavlink_gps_status_t msg{};
+
+			msg.satellites_visible = sat.count;
+
+			size_t sat_count = math::min(static_cast<size_t>(sat.count),
+						     sizeof(msg.satellite_used) / sizeof(msg.satellite_used[0]));
+
+			for (size_t i = 0; i < sat_count; i++) {
+				msg.satellite_used[i]      = sat.used[i];
+				msg.satellite_elevation[i] = sat.elevation[i];
+				msg.satellite_azimuth[i]   = sat.azimuth[i];
+				msg.satellite_snr[i]       = sat.snr[i];
+				msg.satellite_prn[i]       = sat.prn[i];
+			}
+
+			mavlink_msg_gps_status_send_struct(_mavlink->get_channel(), &msg);
+
+			return true;
+		}
+
+		return false;
+	}
+};
+
+#endif // GPS_STATUS_HPP