Added uORB tiny pub/sub for usage without struct on stack.

9 files changed, 232 insertions, 239 deletions

diff --git a/src/drivers/roboclaw/RoboClaw.cpp b/src/drivers/roboclaw/RoboClaw.cpp
index dd5e4d3e0..280f6c831 100644
--- a/src/drivers/roboclaw/RoboClaw.cpp
+++ b/src/drivers/roboclaw/RoboClaw.cpp
@@ -65,7 +65,7 @@ RoboClaw::RoboClaw(const char *deviceName, uint16_t address,
 	_pulsesPerRev(pulsesPerRev),
 	_uart(0),
 	_controlPoll(),
-	_actuators(NULL, ORB_ID(actuator_controls_0), 20),
+	_actuators(ORB_ID(actuator_controls_0), 20),
 	_motor1Position(0),
 	_motor1Speed(0),
 	_motor1Overflow(0),
diff --git a/src/modules/controllib/block/Block.cpp b/src/modules/controllib/block/Block.cpp
index 6768bfa7e..f3cd87728 100644
--- a/src/modules/controllib/block/Block.cpp
+++ b/src/modules/controllib/block/Block.cpp
@@ -101,7 +101,7 @@ void Block::updateParams()
 
 void Block::updateSubscriptions()
 {
-	uORB::SubscriptionBase *sub = getSubscriptions().getHead();
+	uORB::SubscriptionNode *sub = getSubscriptions().getHead();
 	int count = 0;
 
 	while (sub != NULL) {
@@ -119,7 +119,7 @@ void Block::updateSubscriptions()
 
 void Block::updatePublications()
 {
-	uORB::PublicationBase *pub = getPublications().getHead();
+	uORB::PublicationNode *pub = getPublications().getHead();
 	int count = 0;
 
 	while (pub != NULL) {
diff --git a/src/modules/controllib/block/Block.hpp b/src/modules/controllib/block/Block.hpp
index 736698e21..42ca3a742 100644
--- a/src/modules/controllib/block/Block.hpp
+++ b/src/modules/controllib/block/Block.hpp
@@ -46,8 +46,8 @@
 
 // forward declaration
 namespace uORB {
-	class SubscriptionBase;
-	class PublicationBase;
+	class SubscriptionNode;
+	class PublicationNode;
 }
 
 namespace control
@@ -83,15 +83,15 @@ public:
 protected:
 // accessors
 	SuperBlock *getParent() { return _parent; }
-	List<uORB::SubscriptionBase *> & getSubscriptions() { return _subscriptions; }
-	List<uORB::PublicationBase *> & getPublications() { return _publications; }
+	List<uORB::SubscriptionNode *> & getSubscriptions() { return _subscriptions; }
+	List<uORB::PublicationNode *> & getPublications() { return _publications; }
 	List<BlockParamBase *> & getParams() { return _params; }
 // attributes
 	const char *_name;
 	SuperBlock *_parent;
 	float _dt;
-	List<uORB::SubscriptionBase *> _subscriptions;
-	List<uORB::PublicationBase *> _publications;
+	List<uORB::SubscriptionNode *> _subscriptions;
+	List<uORB::PublicationNode *> _publications;
 	List<BlockParamBase *> _params;
 };
 
diff --git a/src/modules/controllib/uorb/blocks.cpp b/src/modules/controllib/uorb/blocks.cpp
index e8fecef0d..454d0db19 100644
--- a/src/modules/controllib/uorb/blocks.cpp
+++ b/src/modules/controllib/uorb/blocks.cpp
@@ -82,16 +82,16 @@ void BlockWaypointGuidance::update(vehicle_global_position_s &pos,
 BlockUorbEnabledAutopilot::BlockUorbEnabledAutopilot(SuperBlock *parent, const char *name) :
 	SuperBlock(parent, name),
 	// subscriptions
-	_att(&getSubscriptions(), ORB_ID(vehicle_attitude), 20),
-	_attCmd(&getSubscriptions(), ORB_ID(vehicle_attitude_setpoint), 20),
-	_ratesCmd(&getSubscriptions(), ORB_ID(vehicle_rates_setpoint), 20),
-	_pos(&getSubscriptions() , ORB_ID(vehicle_global_position), 20),
-	_missionCmd(&getSubscriptions(), ORB_ID(position_setpoint_triplet), 20),
-	_manual(&getSubscriptions(), ORB_ID(manual_control_setpoint), 20),
-	_status(&getSubscriptions(), ORB_ID(vehicle_status), 20),
-	_param_update(&getSubscriptions(), ORB_ID(parameter_update), 1000), // limit to 1 Hz
+	_att(ORB_ID(vehicle_attitude), 20, &getSubscriptions()),
+	_attCmd(ORB_ID(vehicle_attitude_setpoint), 20, &getSubscriptions()),
+	_ratesCmd(ORB_ID(vehicle_rates_setpoint), 20, &getSubscriptions()),
+	_pos(ORB_ID(vehicle_global_position), 20, &getSubscriptions()),
+	_missionCmd(ORB_ID(position_setpoint_triplet), 20, &getSubscriptions()),
+	_manual(ORB_ID(manual_control_setpoint), 20, &getSubscriptions()),
+	_status(ORB_ID(vehicle_status), 20, &getSubscriptions()),
+	_param_update(ORB_ID(parameter_update), 1000, &getSubscriptions()), // limit to 1 Hz
 	// publications
-	_actuators(&getPublications(), ORB_ID(actuator_controls_0))
+	_actuators(ORB_ID(actuator_controls_0), &getPublications())
 {
 }
 
diff --git a/src/modules/mc_att_control/mc_att_control_main.cpp b/src/modules/mc_att_control/mc_att_control_main.cpp
index 20e016da3..b024589a6 100644
--- a/src/modules/mc_att_control/mc_att_control_main.cpp
+++ b/src/modules/mc_att_control/mc_att_control_main.cpp
@@ -60,6 +60,8 @@
 #include <drivers/drv_hrt.h>
 #include <arch/board/board.h>
 #include <uORB/uORB.h>
+#include <uORB/Subscription.hpp>
+#include <uORB/Publication.hpp>
 #include <uORB/topics/vehicle_attitude_setpoint.h>
 #include <uORB/topics/manual_control_setpoint.h>
 #include <uORB/topics/actuator_controls.h>
@@ -111,17 +113,17 @@ private:
 	bool	_task_should_exit;		/**< if true, sensor task should exit */
 	int		_control_task;			/**< task handle for sensor task */
 
-	int		_v_att_sub;				/**< vehicle attitude subscription */
-	int		_v_att_sp_sub;			/**< vehicle attitude setpoint subscription */
-	int		_v_rates_sp_sub;		/**< vehicle rates setpoint subscription */
-	int		_v_control_mode_sub;	/**< vehicle control mode subscription */
-	int		_params_sub;			/**< parameter updates subscription */
-	int		_manual_control_sp_sub;	/**< manual control setpoint subscription */
-	int		_armed_sub;				/**< arming status subscription */
+	uORB::SubscriptionTiny		_v_att_sub;				/**< vehicle attitude subscription */
+	uORB::SubscriptionTiny		_v_att_sp_sub;			/**< vehicle attitude setpoint subscription */
+	uORB::SubscriptionTiny		_v_rates_sp_sub;		/**< vehicle rates setpoint subscription */
+	uORB::SubscriptionTiny		_v_control_mode_sub;	/**< vehicle control mode subscription */
+	uORB::SubscriptionTiny		_params_sub;			/**< parameter updates subscription */
+	uORB::SubscriptionTiny		_manual_control_sp_sub;	/**< manual control setpoint subscription */
+	uORB::SubscriptionTiny		_armed_sub;				/**< arming status subscription */
 
-	orb_advert_t	_att_sp_pub;			/**< attitude setpoint publication */
-	orb_advert_t	_v_rates_sp_pub;		/**< rate setpoint publication */
-	orb_advert_t	_actuators_0_pub;		/**< attitude actuator controls publication */
+	uORB::PublicationTiny	_att_sp_pub;			/**< attitude setpoint publication */
+	uORB::PublicationTiny	_v_rates_sp_pub;		/**< rate setpoint publication */
+	uORB::PublicationTiny	_actuators_0_pub;		/**< attitude actuator controls publication */
 
 	struct vehicle_attitude_s			_v_att;				/**< vehicle attitude */
 	struct vehicle_attitude_setpoint_s	_v_att_sp;			/**< vehicle attitude setpoint */
@@ -187,36 +189,6 @@ private:
 	int			parameters_update();
 
 	/**
-	 * Check for parameter update and handle it.
-	 */
-	void		parameter_update_poll();
-
-	/**
-	 * Check for changes in vehicle control mode.
-	 */
-	void		vehicle_control_mode_poll();
-
-	/**
-	 * Check for changes in manual inputs.
-	 */
-	void		vehicle_manual_poll();
-
-	/**
-	 * Check for attitude setpoint updates.
-	 */
-	void		vehicle_attitude_setpoint_poll();
-
-	/**
-	 * Check for rates setpoint updates.
-	 */
-	void		vehicle_rates_setpoint_poll();
-
-	/**
-	 * Check for arming status updates.
-	 */
-	void		arming_status_poll();
-
-	/**
 	 * Attitude controller.
 	 */
 	void		control_attitude(float dt);
@@ -255,17 +227,18 @@ MulticopterAttitudeControl::MulticopterAttitudeControl() :
 	_control_task(-1),
 
 /* subscriptions */
-	_v_att_sub(-1),
-	_v_att_sp_sub(-1),
-	_v_control_mode_sub(-1),
-	_params_sub(-1),
-	_manual_control_sp_sub(-1),
-	_armed_sub(-1),
+	_v_att_sub(ORB_ID(vehicle_attitude)),
+	_v_att_sp_sub(ORB_ID(vehicle_attitude_setpoint)),
+	_v_rates_sp_sub(ORB_ID(vehicle_rates_setpoint)),
+	_v_control_mode_sub(ORB_ID(vehicle_control_mode)),
+	_params_sub(ORB_ID(parameter_update)),
+	_manual_control_sp_sub(ORB_ID(manual_control_setpoint)),
+	_armed_sub(ORB_ID(actuator_armed)),
 
 /* publications */
-	_att_sp_pub(-1),
-	_v_rates_sp_pub(-1),
-	_actuators_0_pub(-1),
+	_att_sp_pub(ORB_ID(vehicle_attitude_setpoint)),
+	_v_rates_sp_pub(ORB_ID(vehicle_rates_setpoint)),
+	_actuators_0_pub(ORB_ID_VEHICLE_ATTITUDE_CONTROLS),
 
 /* performance counters */
 	_loop_perf(perf_alloc(PC_ELAPSED, "mc_att_control"))
@@ -405,83 +378,6 @@ MulticopterAttitudeControl::parameters_update()
 	return OK;
 }
 
-void
-MulticopterAttitudeControl::parameter_update_poll()
-{
-	bool updated;
-
-	/* Check HIL state if vehicle status has changed */
-	orb_check(_params_sub, &updated);
-
-	if (updated) {
-		struct parameter_update_s param_update;
-		orb_copy(ORB_ID(parameter_update), _params_sub, &param_update);
-		parameters_update();
-	}
-}
-
-void
-MulticopterAttitudeControl::vehicle_control_mode_poll()
-{
-	bool updated;
-
-	/* Check HIL state if vehicle status has changed */
-	orb_check(_v_control_mode_sub, &updated);
-
-	if (updated) {
-		orb_copy(ORB_ID(vehicle_control_mode), _v_control_mode_sub, &_v_control_mode);
-	}
-}
-
-void
-MulticopterAttitudeControl::vehicle_manual_poll()
-{
-	bool updated;
-
-	/* get pilots inputs */
-	orb_check(_manual_control_sp_sub, &updated);
-
-	if (updated) {
-		orb_copy(ORB_ID(manual_control_setpoint), _manual_control_sp_sub, &_manual_control_sp);
-	}
-}
-
-void
-MulticopterAttitudeControl::vehicle_attitude_setpoint_poll()
-{
-	/* check if there is a new setpoint */
-	bool updated;
-	orb_check(_v_att_sp_sub, &updated);
-
-	if (updated) {
-		orb_copy(ORB_ID(vehicle_attitude_setpoint), _v_att_sp_sub, &_v_att_sp);
-	}
-}
-
-void
-MulticopterAttitudeControl::vehicle_rates_setpoint_poll()
-{
-	/* check if there is a new setpoint */
-	bool updated;
-	orb_check(_v_rates_sp_sub, &updated);
-
-	if (updated) {
-		orb_copy(ORB_ID(vehicle_rates_setpoint), _v_rates_sp_sub, &_v_rates_sp);
-	}
-}
-
-void
-MulticopterAttitudeControl::arming_status_poll()
-{
-	/* check if there is a new setpoint */
-	bool updated;
-	orb_check(_armed_sub, &updated);
-
-	if (updated) {
-		orb_copy(ORB_ID(actuator_armed), _armed_sub, &_armed);
-	}
-}
-
 /*
  * Attitude controller.
  * Input: 'manual_control_setpoint' and 'vehicle_attitude_setpoint' topics (depending on mode)
@@ -498,7 +394,7 @@ MulticopterAttitudeControl::control_attitude(float dt)
 
 		if (_v_control_mode.flag_control_velocity_enabled || _v_control_mode.flag_control_climb_rate_enabled) {
 			/* in assisted modes poll 'vehicle_attitude_setpoint' topic and modify it */
-			vehicle_attitude_setpoint_poll();
+			(void) _v_att_sp_sub.update(&_v_att_sp);
 		}
 
 		if (!_v_control_mode.flag_control_climb_rate_enabled) {
@@ -553,7 +449,7 @@ MulticopterAttitudeControl::control_attitude(float dt)
 
 	} else {
 		/* in non-manual mode use 'vehicle_attitude_setpoint' topic */
-		vehicle_attitude_setpoint_poll();
+		(void) _v_att_sp_sub.update(&_v_att_sp);
 
 		/* reset yaw setpoint after non-manual control mode */
 		_reset_yaw_sp = true;
@@ -581,12 +477,7 @@ MulticopterAttitudeControl::control_attitude(float dt)
 	if (publish_att_sp) {
 		_v_att_sp.timestamp = hrt_absolute_time();
 
-		if (_att_sp_pub > 0) {
-			orb_publish(ORB_ID(vehicle_attitude_setpoint), _att_sp_pub, &_v_att_sp);
-
-		} else {
-			_att_sp_pub = orb_advertise(ORB_ID(vehicle_attitude_setpoint), &_v_att_sp);
-		}
+		_att_sp_pub.update(&_v_att_sp);
 	}
 
 	/* rotation matrix for current state */
@@ -717,24 +608,13 @@ MulticopterAttitudeControl::task_main()
 	warnx("started");
 	fflush(stdout);
 
-	/*
-	 * do subscriptions
-	 */
-	_v_att_sp_sub = orb_subscribe(ORB_ID(vehicle_attitude_setpoint));
-	_v_rates_sp_sub = orb_subscribe(ORB_ID(vehicle_rates_setpoint));
-	_v_att_sub = orb_subscribe(ORB_ID(vehicle_attitude));
-	_v_control_mode_sub = orb_subscribe(ORB_ID(vehicle_control_mode));
-	_params_sub = orb_subscribe(ORB_ID(parameter_update));
-	_manual_control_sp_sub = orb_subscribe(ORB_ID(manual_control_setpoint));
-	_armed_sub = orb_subscribe(ORB_ID(actuator_armed));
-
 	/* initialize parameters cache */
 	parameters_update();
 
 	/* wakeup source: vehicle attitude */
 	struct pollfd fds[1];
 
-	fds[0].fd = _v_att_sub;
+	fds[0].fd = _v_att_sub.getHandle();
 	fds[0].events = POLLIN;
 
 	while (!_task_should_exit) {
@@ -771,13 +651,15 @@ MulticopterAttitudeControl::task_main()
 			}
 
 			/* copy attitude topic */
-			orb_copy(ORB_ID(vehicle_attitude), _v_att_sub, &_v_att);
+			_v_att_sub.update(&_v_att);
 
 			/* check for updates in other topics */
-			parameter_update_poll();
-			vehicle_control_mode_poll();
-			arming_status_poll();
-			vehicle_manual_poll();
+			if (_params_sub.updated()) {
+				parameters_update();
+			}
+			(void) _v_control_mode_sub.update(&_v_control_mode);
+			(void) _armed_sub.update(&_armed);
+			(void) _manual_control_sp_sub.update(&_manual_control_sp);
 
 			if (_v_control_mode.flag_control_attitude_enabled) {
 				control_attitude(dt);
@@ -789,12 +671,7 @@ MulticopterAttitudeControl::task_main()
 				_v_rates_sp.thrust = _thrust_sp;
 				_v_rates_sp.timestamp = hrt_absolute_time();
 
-				if (_v_rates_sp_pub > 0) {
-					orb_publish(ORB_ID(vehicle_rates_setpoint), _v_rates_sp_pub, &_v_rates_sp);
-
-				} else {
-					_v_rates_sp_pub = orb_advertise(ORB_ID(vehicle_rates_setpoint), &_v_rates_sp);
-				}
+				_v_rates_sp_pub.update(&_v_rates_sp);
 
 			} else {
 				/* attitude controller disabled, poll rates setpoint topic */
@@ -813,16 +690,11 @@ MulticopterAttitudeControl::task_main()
 					_v_rates_sp.thrust = _thrust_sp;
 					_v_rates_sp.timestamp = hrt_absolute_time();
 
-					if (_v_rates_sp_pub > 0) {
-						orb_publish(ORB_ID(vehicle_rates_setpoint), _v_rates_sp_pub, &_v_rates_sp);
-
-					} else {
-						_v_rates_sp_pub = orb_advertise(ORB_ID(vehicle_rates_setpoint), &_v_rates_sp);
-					}
+					_v_rates_sp_pub.update(&_v_rates_sp);
 
 				} else {
 					/* attitude controller disabled, poll rates setpoint topic */
-					vehicle_rates_setpoint_poll();
+					_v_rates_sp_sub.update(&_v_rates_sp);
 					_rates_sp(0) = _v_rates_sp.roll;
 					_rates_sp(1) = _v_rates_sp.pitch;
 					_rates_sp(2) = _v_rates_sp.yaw;
@@ -840,12 +712,7 @@ MulticopterAttitudeControl::task_main()
 				_actuators.control[3] = (isfinite(_thrust_sp)) ? _thrust_sp : 0.0f;
 				_actuators.timestamp = hrt_absolute_time();
 
-				if (_actuators_0_pub > 0) {
-					orb_publish(ORB_ID(actuator_controls_0), _actuators_0_pub, &_actuators);
-
-				} else {
-					_actuators_0_pub = orb_advertise(ORB_ID(actuator_controls_0), &_actuators);
-				}
+				_actuators_0_pub.update(&_actuators);
 			}
 		}
 
diff --git a/src/modules/uORB/Publication.cpp b/src/modules/uORB/Publication.cpp
index 5a5981617..e9398a625 100644
--- a/src/modules/uORB/Publication.cpp
+++ b/src/modules/uORB/Publication.cpp
@@ -52,10 +52,10 @@ namespace uORB {
 
 template<class T>
 Publication<T>::Publication(
-	List<PublicationBase *> * list,
-	const struct orb_metadata *meta) :
+	const struct orb_metadata *meta,
+	List<PublicationNode *> * list) :
 	T(), // initialize data structure to zero
-	PublicationBase(list, meta) {
+	PublicationNode(meta, list) {
 }
 
 template<class T>
diff --git a/src/modules/uORB/Publication.hpp b/src/modules/uORB/Publication.hpp
index 8650b3df8..1c48929e4 100644
--- a/src/modules/uORB/Publication.hpp
+++ b/src/modules/uORB/Publication.hpp
@@ -38,6 +38,8 @@
 
 #pragma once
 
+#include <assert.h>
+
 #include <uORB/uORB.h>
 #include <containers/List.hpp>
 
@@ -49,55 +51,112 @@ namespace uORB
  * Base publication warapper class, used in list traversal
  * of various publications.
  */
-class __EXPORT PublicationBase : public ListNode<uORB::PublicationBase *>
+class __EXPORT PublicationBase
 {
 public:
 
-	PublicationBase(
-		List<PublicationBase *> * list,
-		const struct orb_metadata *meta) :
+	/**
+	 * Constructor
+	 *
+	 *
+	 * @param meta The uORB metadata (usually from the ORB_ID() 
+	 * 	macro) for the topic.
+	 */
+	PublicationBase(const struct orb_metadata *meta) :
 		_meta(meta),
 		_handle(-1) {
-		if (list != NULL) list->add(this);
 	}
-	void update() {
+
+	/**
+	 * Update the struct
+	 * @param data The uORB message struct we are updating.
+	 */
+	void update(void * data) {
 		if (_handle > 0) {
-			orb_publish(getMeta(), getHandle(), getDataVoidPtr());
+			orb_publish(getMeta(), getHandle(), data);
 		} else {
-			setHandle(orb_advertise(getMeta(), getDataVoidPtr()));
+			setHandle(orb_advertise(getMeta(), data));
 		}
 	}
-	virtual void *getDataVoidPtr() = 0;
+
+	/**
+	 * Deconstructor
+	 */
 	virtual ~PublicationBase() {
 		orb_unsubscribe(getHandle());
 	}
+// accessors
 	const struct orb_metadata *getMeta() { return _meta; }
 	int getHandle() { return _handle; }
 protected:
+// accessors
 	void setHandle(orb_advert_t handle) { _handle = handle; }
+// attributes
 	const struct orb_metadata *_meta;
 	orb_advert_t _handle;
 };
 
+/** 
+ * alias class name so it is clear that the base class
+ * can be used by itself if desired
+ */
+typedef PublicationBase PublicationTiny;
+
+/**
+ * The publication base class as a list node.
+ */
+class __EXPORT PublicationNode :
+	public PublicationBase,
+	public ListNode<PublicationNode *>
+{
+public:
+	/**
+	 * Constructor
+	 *
+	 *
+	 * @param meta The uORB metadata (usually from the ORB_ID() 
+	 * 	macro) for the topic.
+	 * @param list 	A pointer to a list of subscriptions 
+	 * 	that this should be appended to.
+	 */
+	PublicationNode(const struct orb_metadata *meta,
+		List<PublicationNode *> * list=nullptr) :
+		PublicationBase(meta) {
+		if (list != nullptr) list->add(this);
+	}
+
+	/**
+	 * This function is the callback for list traversal
+	 * updates, a child class must implement it.
+	 */
+	virtual void update() = 0;
+};
+
 /**
  * Publication wrapper class
  */
 template<class T>
 class Publication :
 	public T, // this must be first!
-	public PublicationBase
+	public PublicationNode
 {
 public:
 	/**
 	 * Constructor
 	 *
-	 * @param list      A list interface for adding to list during construction
-	 * @param meta		The uORB metadata (usually from the ORB_ID() macro)
-	 *			for the topic.
+	 * @param meta The uORB metadata (usually from 
+	 * 	the ORB_ID() macro) for the topic.
+	 * @param list A list interface for adding to
+	 * 	list during construction
 	 */
-	Publication(List<PublicationBase *> * list,
-		const struct orb_metadata *meta);
+	Publication(const struct orb_metadata *meta,
+		List<PublicationNode *> * list=nullptr);
+
+	/**
+	 * Deconstructor
+	 **/
 	virtual ~Publication();
+
 	/*
 	 * XXX
 	 * This function gets the T struct, assuming
@@ -106,6 +165,13 @@ public:
 	 * seem to be available
 	 */
 	void *getDataVoidPtr();
+
+	/**
+	 * Create an update function that uses the embedded struct.
+	 */
+	void update() {
+		PublicationBase::update(getDataVoidPtr());
+	}
 };
 
 } // namespace uORB
diff --git a/src/modules/uORB/Subscription.cpp b/src/modules/uORB/Subscription.cpp
index c1d1a938f..1a4867c85 100644
--- a/src/modules/uORB/Subscription.cpp
+++ b/src/modules/uORB/Subscription.cpp
@@ -55,21 +55,13 @@
 namespace uORB
 {
 
-bool __EXPORT SubscriptionBase::updated()
-{
-	bool isUpdated = false;
-	orb_check(_handle, &isUpdated);
-	return isUpdated;
-}
-
 template<class T>
 Subscription<T>::Subscription(
-	List<SubscriptionBase *> * list,
-	const struct orb_metadata *meta, unsigned interval) :
+	const struct orb_metadata *meta,
+	unsigned interval,
+	List<SubscriptionNode *> * list) :
 	T(), // initialize data structure to zero
-	SubscriptionBase(list, meta) {
-	setHandle(orb_subscribe(getMeta()));
-	orb_set_interval(getHandle(), interval);
+	SubscriptionNode(meta, interval, list) {
 }
 
 template<class T>
diff --git a/src/modules/uORB/Subscription.hpp b/src/modules/uORB/Subscription.hpp
index 34e9a83e0..bab1ef2ea 100644
--- a/src/modules/uORB/Subscription.hpp
+++ b/src/modules/uORB/Subscription.hpp
@@ -38,10 +38,11 @@
 
 #pragma once
 
+#include <assert.h>
+
 #include <uORB/uORB.h>
 #include <containers/List.hpp>
 
-
 namespace uORB
 {
 
@@ -49,8 +50,7 @@ namespace uORB
  * Base subscription warapper class, used in list traversal
  * of various subscriptions.
  */
-class __EXPORT SubscriptionBase :
-	public ListNode<SubscriptionBase *>
+class __EXPORT SubscriptionBase
 {
 public:
 // methods
@@ -58,23 +58,42 @@ public:
 	/**
 	 * Constructor
 	 *
-	 * @param meta		The uORB metadata (usually from the ORB_ID() macro)
-	 *			for the topic.
+	 * @param meta The uORB metadata (usually from the ORB_ID() 
+	 * 	macro) for the topic.
+	 *
+	 * @param interval  The minimum interval in milliseconds 
+	 * 	between updates
 	 */
-	SubscriptionBase(
-		List<SubscriptionBase *> * list,
-		const struct orb_metadata *meta) :
+	SubscriptionBase(const struct orb_metadata *meta,
+		unsigned interval=0) :
 		_meta(meta),
 		_handle() {
-		if (list != NULL) list->add(this);
+		setHandle(orb_subscribe(getMeta()));
+		orb_set_interval(getHandle(), interval);
 	}
-	bool updated();
-	void update() {
+
+	/**
+	 * Check if there is a new update.
+	 * */
+	bool updated() {
+		bool isUpdated = false;
+		orb_check(_handle, &isUpdated);
+		return isUpdated;
+	}
+
+	/**
+	 * Update the struct
+	 * @param data The uORB message struct we are updating.
+	 */
+	void update(void * data) {
 		if (updated()) {
-			orb_copy(_meta, _handle, getDataVoidPtr());
+			orb_copy(_meta, _handle, data);
 		}
 	}
-	virtual void *getDataVoidPtr() = 0;
+
+	/**
+	 * Deconstructor
+	 */
 	virtual ~SubscriptionBase() {
 		orb_unsubscribe(_handle);
 	}
@@ -90,30 +109,79 @@ protected:
 };
 
 /**
+ * alias class name so it is clear that the base class
+ */
+typedef SubscriptionBase SubscriptionTiny;
+
+/**
+ * The publication base class as a list node.
+ */
+class __EXPORT SubscriptionNode :
+
+	public SubscriptionBase,
+	public ListNode<SubscriptionNode *>
+{
+public:
+	/**
+	 * Constructor
+	 *
+	 *
+	 * @param meta The uORB metadata (usually from the ORB_ID() 
+	 * 	macro) for the topic.
+	 * @param interval  The minimum interval in milliseconds 
+	 * 	between updates
+	 * @param list 	A pointer to a list of subscriptions 
+	 * 	that this should be appended to.
+	 */
+	SubscriptionNode(const struct orb_metadata *meta,
+		unsigned interval=0,
+		List<SubscriptionNode *> * list=nullptr) :
+		SubscriptionBase(meta, interval) {
+		if (list != nullptr) list->add(this);
+	}
+
+	/**
+	 * This function is the callback for list traversal
+	 * updates, a child class must implement it.
+	 */
+	virtual void update() = 0;
+};
+
+/**
  * Subscription wrapper class
  */
 template<class T>
 class __EXPORT Subscription :
 	public T, // this must be first!
-	public SubscriptionBase
+	public SubscriptionNode
 {
 public:
 	/**
 	 * Constructor
 	 *
-	 * @param list      A list interface for adding to list during construction
-	 * @param meta		The uORB metadata (usually from the ORB_ID() macro)
-	 *			for the topic.
-	 * @param interval  The minimum interval in milliseconds between updates
+	 * @param meta The uORB metadata (usually from 
+	 * 	the ORB_ID() macro) for the topic.
+	 * @param interval  The minimum interval in milliseconds 
+	 * 	between updates
+	 * @param list A list interface for adding to 
+	 * 	list during construction
 	 */
-	Subscription(
-		List<SubscriptionBase *> * list,
-		const struct orb_metadata *meta, unsigned interval);
+	Subscription(const struct orb_metadata *meta, 
+		unsigned interval=0,
+		List<SubscriptionNode *> * list=nullptr);
 	/**
 	 * Deconstructor
 	 */
 	virtual ~Subscription();
 
+
+	/**
+	 * Create an update function that uses the embedded struct.
+	 */
+	void update() {
+		SubscriptionBase::update(getDataVoidPtr());
+	}
+
 	/*
 	 * XXX
 	 * This function gets the T struct, assuming