Merge pull request #1505 from mhkabir/timesync

Timesync

src/modules/mavlink/mavlink_main.cpp

@@ -1419,6 +1419,8 @@ Mavlink::task_main(int argc, char *argv[])
 		configure_stream("DISTANCE_SENSOR", 10.0f);
 		configure_stream("OPTICAL_FLOW_RAD", 10.0f);
 		configure_stream("VFR_HUD", 10.0f);
+		configure_stream("SYSTEM_TIME", 1.0f);
+		configure_stream("TIMESYNC", 10.0f);
 		break;
 
 	default:

src/modules/mavlink/mavlink_messages.cpp

@@ -923,6 +923,92 @@ protected:
 	}
 };
 
+class MavlinkStreamSystemTime : public MavlinkStream
+{
+public:
+	const char *get_name() const {
+		return MavlinkStreamSystemTime::get_name_static();
+	}
+
+	static const char *get_name_static() {
+		return "SYSTEM_TIME";
+	}
+
+	uint8_t get_id() {
+		return MAVLINK_MSG_ID_SYSTEM_TIME;
+	}
+
+	static MavlinkStream *new_instance(Mavlink *mavlink) {
+		return new MavlinkStreamSystemTime(mavlink);
+	}
+
+	unsigned get_size() {
+		return MAVLINK_MSG_ID_SYSTEM_TIME_LEN + MAVLINK_NUM_NON_PAYLOAD_BYTES;
+	}
+
+private:
+	/* do not allow top copying this class */
+	MavlinkStreamSystemTime(MavlinkStreamSystemTime &);
+	MavlinkStreamSystemTime &operator = (const MavlinkStreamSystemTime &);
+
+protected:
+	explicit MavlinkStreamSystemTime(Mavlink *mavlink) : MavlinkStream(mavlink)
+	{}
+
+	void send(const hrt_abstime t) {
+		mavlink_system_time_t msg;
+		timespec tv;
+
+		clock_gettime(CLOCK_REALTIME, &tv);
+
+		msg.time_boot_ms = hrt_absolute_time() / 1000;
+		msg.time_unix_usec = (uint64_t)tv.tv_sec * 1000000 + tv.tv_nsec / 1000;
+
+		_mavlink->send_message(MAVLINK_MSG_ID_SYSTEM_TIME, &msg);
+	}
+};
+
+class MavlinkStreamTimesync : public MavlinkStream
+{
+public:
+	const char *get_name() const {
+		return MavlinkStreamTimesync::get_name_static();
+	}
+
+	static const char *get_name_static() {
+		return "TIMESYNC";
+	}
+
+	uint8_t get_id() {
+		return MAVLINK_MSG_ID_TIMESYNC;
+	}
+
+	static MavlinkStream *new_instance(Mavlink *mavlink) {
+		return new MavlinkStreamTimesync(mavlink);
+	}
+
+	unsigned get_size() {
+		return MAVLINK_MSG_ID_TIMESYNC_LEN + MAVLINK_NUM_NON_PAYLOAD_BYTES;
+	}
+
+private:
+	/* do not allow top copying this class */
+	MavlinkStreamTimesync(MavlinkStreamTimesync &);
+	MavlinkStreamTimesync &operator = (const MavlinkStreamTimesync &);
+
+protected:
+	explicit MavlinkStreamTimesync(Mavlink *mavlink) : MavlinkStream(mavlink)
+	{}
+
+	void send(const hrt_abstime t) {
+		mavlink_timesync_t msg;
+
+		msg.tc1 = 0;
+		msg.ts1 = hrt_absolute_time() * 1000; // boot time in nanoseconds
+
+		_mavlink->send_message(MAVLINK_MSG_ID_TIMESYNC, &msg);
+	}
+};
 
 class MavlinkStreamGlobalPositionInt : public MavlinkStream
 {
@@ -2197,6 +2283,8 @@ StreamListItem *streams_list[] = {
 	new StreamListItem(&MavlinkStreamAttitudeQuaternion::new_instance, &MavlinkStreamAttitudeQuaternion::get_name_static),
 	new StreamListItem(&MavlinkStreamVFRHUD::new_instance, &MavlinkStreamVFRHUD::get_name_static),
 	new StreamListItem(&MavlinkStreamGPSRawInt::new_instance, &MavlinkStreamGPSRawInt::get_name_static),
+	new StreamListItem(&MavlinkStreamSystemTime::new_instance, &MavlinkStreamSystemTime::get_name_static),
+	new StreamListItem(&MavlinkStreamTimesync::new_instance, &MavlinkStreamTimesync::get_name_static),
 	new StreamListItem(&MavlinkStreamGlobalPositionInt::new_instance, &MavlinkStreamGlobalPositionInt::get_name_static),
 	new StreamListItem(&MavlinkStreamLocalPositionNED::new_instance, &MavlinkStreamLocalPositionNED::get_name_static),
 	new StreamListItem(&MavlinkStreamViconPositionEstimate::new_instance, &MavlinkStreamViconPositionEstimate::get_name_static),

src/modules/mavlink/mavlink_receiver.cpp

@@ -123,7 +123,9 @@ MavlinkReceiver::MavlinkReceiver(Mavlink *parent) :
 	_old_timestamp(0),
 	_hil_local_proj_inited(0),
 	_hil_local_alt0(0.0f),
-	_hil_local_proj_ref{}
+	_hil_local_proj_ref{},
+	_time_offset_avg_alpha(0.6),
+	_time_offset(0)
 {
 
 	// make sure the FTP server is started
@@ -190,6 +192,14 @@ MavlinkReceiver::handle_message(mavlink_message_t *msg)
 		MavlinkFTP::get_server()->handle_message(_mavlink, msg);
 		break;
 
+	case MAVLINK_MSG_ID_SYSTEM_TIME:
+		handle_message_system_time(msg);
+		break;
+
+	case MAVLINK_MSG_ID_TIMESYNC:
+		handle_message_timesync(msg);
+		break;
+
 	default:
 		break;
 	}
@@ -698,7 +708,7 @@ MavlinkReceiver::handle_message_vision_position_estimate(mavlink_message_t *msg)
 	// Use the component ID to identify the vision sensor
 	vision_position.id = msg->compid;
 
-	vision_position.timestamp_boot = hrt_absolute_time();
+	vision_position.timestamp_boot = to_hrt(pos.usec); // Synced time
 	vision_position.timestamp_computer = pos.usec;
 	vision_position.x = pos.x;
 	vision_position.y = pos.y;
@@ -927,6 +937,63 @@ MavlinkReceiver::handle_message_request_data_stream(mavlink_message_t *msg)
 	}
 }
 
+void
+MavlinkReceiver::handle_message_system_time(mavlink_message_t *msg)
+{
+	mavlink_system_time_t time;
+	mavlink_msg_system_time_decode(msg, &time);
+
+	timespec tv;
+	clock_gettime(CLOCK_REALTIME, &tv);
+
+	// date -d @1234567890: Sat Feb 14 02:31:30 MSK 2009
+	bool onb_unix_valid = tv.tv_sec > 1234567890L;
+	bool ofb_unix_valid = time.time_unix_usec > 1234567890L * 1000;
+
+	if (!onb_unix_valid && ofb_unix_valid) {
+		tv.tv_sec = time.time_unix_usec / 1000000;
+		tv.tv_nsec = (time.time_unix_usec % 1000000) * 1000;
+		clock_settime(CLOCK_REALTIME, &tv);
+		warnx("[timesync] Set system time from SYSTEM_TIME message");
+	}
+
+}
+
+void
+MavlinkReceiver::handle_message_timesync(mavlink_message_t *msg)
+{
+	mavlink_timesync_t tsync;
+	mavlink_msg_timesync_decode(msg, &tsync);
+
+	uint64_t now_ns = hrt_absolute_time() * 1000 ;
+
+	if (tsync.tc1 == 0) {
+
+		mavlink_timesync_t rsync; // return timestamped sync message
+
+		rsync.tc1 = now_ns;
+		rsync.ts1 = tsync.ts1;
+
+		_mavlink->send_message(MAVLINK_MSG_ID_TIMESYNC, &rsync);
+
+		return;
+
+	} else if (tsync.tc1 > 0) {
+
+		int64_t offset_ns = (9*_time_offset + (tsync.ts1 + now_ns - tsync.tc1*2)/2 )/10; // average offset
+		int64_t dt = _time_offset - offset_ns;
+
+		if (dt > 10000000 || dt < -1000000) { // 10 millisecond skew 
+			_time_offset = (tsync.ts1 + now_ns - tsync.tc1*2)/2; 
+			warnx("[timesync] Companion clock offset is skewed. Hard-setting offset");
+
+		} else {
+			smooth_time_offset(offset_ns);
+		}
+	}
+
+}
+
 void
 MavlinkReceiver::handle_message_hil_sensor(mavlink_message_t *msg)
 {
@@ -1394,6 +1461,23 @@ void MavlinkReceiver::print_status()
 
 }
 
+uint64_t MavlinkReceiver::to_hrt(uint64_t usec)
+{
+	return usec - (_time_offset / 1000) ;
+}
+
+
+void MavlinkReceiver::smooth_time_offset(uint64_t offset_ns)
+{
+	/* alpha = 0.75 fixed for now. The closer alpha is to 1.0,
+         * the faster the moving average updates in response to
+	 * new offset samples.
+	 */
+
+ 	_time_offset = (_time_offset_avg_alpha * offset_ns) + (1.0 - _time_offset_avg_alpha) * _time_offset;
+}
+
+
 void *MavlinkReceiver::start_helper(void *context)
 {
 	MavlinkReceiver *rcv = new MavlinkReceiver((Mavlink *)context);

src/modules/mavlink/mavlink_receiver.h

@@ -124,12 +124,23 @@ private:
 	void handle_message_manual_control(mavlink_message_t *msg);
 	void handle_message_heartbeat(mavlink_message_t *msg);
 	void handle_message_request_data_stream(mavlink_message_t *msg);
+	void handle_message_system_time(mavlink_message_t *msg);
+	void handle_message_timesync(mavlink_message_t *msg);
 	void handle_message_hil_sensor(mavlink_message_t *msg);
 	void handle_message_hil_gps(mavlink_message_t *msg);
 	void handle_message_hil_state_quaternion(mavlink_message_t *msg);
 
 	void *receive_thread(void *arg);
 
+	/**
+	* Convert remote nsec timestamp to local hrt time (usec)
+	*/
+	uint64_t to_hrt(uint64_t nsec);
+	/**
+	* Exponential moving average filter to smooth time offset
+	*/
+	void smooth_time_offset(uint64_t offset_ns);	
+
 	mavlink_status_t status;
 	struct vehicle_local_position_s hil_local_pos;
 	struct vehicle_control_mode_s _control_mode;
@@ -164,6 +175,8 @@ private:
 	bool _hil_local_proj_inited;
 	float _hil_local_alt0;
 	struct map_projection_reference_s _hil_local_proj_ref;
+	double _time_offset_avg_alpha;
+	uint64_t _time_offset;
 
 	/* do not allow copying this class */
 	MavlinkReceiver(const MavlinkReceiver&);