mavlink_messages: add GPS_GLOBAL_ORIGIN

sending out local position reference.
Only send as anser to a request message command or
when the origin was changed from externally to verify.

src/modules/mavlink/mavlink_messages.cpp

@@ -113,6 +113,7 @@ using matrix::wrap_2pi;
 #include "streams/ESC_STATUS.hpp"
 #include "streams/EXTENDED_SYS_STATE.hpp"
 #include "streams/FLIGHT_INFORMATION.hpp"
+#include "streams/GPS_GLOBAL_ORIGIN.hpp"
 #include "streams/GPS_STATUS.hpp"
 #include "streams/HIGH_LATENCY2.hpp"
 #include "streams/HIL_STATE_QUATERNION.hpp"
@@ -4301,6 +4302,9 @@ static const StreamListItem streams_list[] = {
 	create_stream_list_item<MavlinkStreamAttitude>(),
 	create_stream_list_item<MavlinkStreamAttitudeQuaternion>(),
 	create_stream_list_item<MavlinkStreamVFRHUD>(),
+#if defined(GPS_GLOBAL_ORIGIN_HPP)
+	create_stream_list_item<MavlinkStreamGpsGlobalOrigin>(),
+#endif // GPS_GLOBAL_ORIGIN_HPP
 	create_stream_list_item<MavlinkStreamGPSRawInt>(),
 	create_stream_list_item<MavlinkStreamGPS2Raw>(),
 	create_stream_list_item<MavlinkStreamSystemTime>(),

src/modules/mavlink/mavlink_receiver.cpp

@@ -1229,6 +1229,8 @@ MavlinkReceiver::handle_message_set_gps_global_origin(mavlink_message_t *msg)
 					  (float)origin.altitude * 1.0e-3f, hrt_absolute_time());
 		_global_ref_timestamp = hrt_absolute_time();
 	}
+
+	handle_request_message_command(MAVLINK_MSG_ID_GPS_GLOBAL_ORIGIN);
 }
 
 void

src/modules/mavlink/streams/GPS_GLOBAL_ORIGIN.hpp

@@ -0,0 +1,106 @@
+/****************************************************************************
+ *
+ *   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_GLOBAL_ORIGIN_HPP
+#define GPS_GLOBAL_ORIGIN_HPP
+
+#include <uORB/topics/vehicle_local_position.h>
+
+class MavlinkStreamGpsGlobalOrigin : public MavlinkStream
+{
+public:
+	const char *get_name() const override
+	{
+		return MavlinkStreamGpsGlobalOrigin::get_name_static();
+	}
+
+	static constexpr const char *get_name_static()
+	{
+		return "GPS_GLOBAL_ORIGIN";
+	}
+
+	static constexpr uint16_t get_id_static()
+	{
+		return MAVLINK_MSG_ID_GPS_GLOBAL_ORIGIN;
+	}
+
+	uint16_t get_id() override
+	{
+		return get_id_static();
+	}
+
+	static MavlinkStream *new_instance(Mavlink *mavlink)
+	{
+		return new MavlinkStreamGpsGlobalOrigin(mavlink);
+	}
+
+	unsigned get_size() override
+	{
+		return _vehicle_local_position_sub.advertised() ?
+		       (MAVLINK_MSG_ID_GPS_GLOBAL_ORIGIN_LEN + MAVLINK_NUM_NON_PAYLOAD_BYTES) : 0;
+	}
+
+private:
+	uORB::Subscription _vehicle_local_position_sub{ORB_ID(vehicle_local_position)};
+
+	/* do not allow top copying this class */
+	MavlinkStreamGpsGlobalOrigin(MavlinkStreamGpsGlobalOrigin &) = delete;
+	MavlinkStreamGpsGlobalOrigin &operator = (const MavlinkStreamGpsGlobalOrigin &) = delete;
+
+protected:
+	explicit MavlinkStreamGpsGlobalOrigin(Mavlink *mavlink) : MavlinkStream(mavlink)
+	{}
+
+	bool send() override
+	{
+		vehicle_local_position_s vehicle_local_position;
+
+		if (_vehicle_local_position_sub.update(&vehicle_local_position)) {
+			mavlink_gps_global_origin_t msg{};
+
+			if (vehicle_local_position.ref_timestamp > 0) {
+				msg.latitude = static_cast<int32_t>(vehicle_local_position.ref_lat * 1e7); // double degree -> int32 degreeE7
+				msg.longitude = static_cast<int32_t>(vehicle_local_position.ref_lon * 1e7); // double degree -> int32 degreeE7
+				msg.altitude = static_cast<int32_t>(vehicle_local_position.ref_alt * 1e3f); // float m -> int32 mm
+				msg.time_usec = vehicle_local_position.timestamp; // int64 time since system boot
+			}
+
+			mavlink_msg_gps_global_origin_send_struct(_mavlink->get_channel(), &msg);
+			return true;
+		}
+
+		return false;
+	}
+};
+
+#endif // GPS_GLOBAL_ORIGIN_HPP