boards: add CONSTRAINED_MEMORY build option

- currently the main change is that it reduces the max number of ORB multi instances to 4, but usage will be expanded as needed
 - limits number of EKF2 multi instances to 2.
 - enabled on all cortex m4 boards

src/modules/ekf2/EKF2Selector.hpp

@@ -53,8 +53,11 @@
 #include <uORB/topics/vehicle_global_position.h>
 #include <uORB/topics/vehicle_odometry.h>
 
-static constexpr uint8_t EKF2_MAX_INSTANCES{9};
-static_assert(EKF2_MAX_INSTANCES <= ORB_MULTI_MAX_INSTANCES, "EKF2_MAX_INSTANCES must be <= ORB_MULTI_MAX_INSTANCES");
+#if CONSTRAINED_MEMORY
+# define EKF2_MAX_INSTANCES 2
+#else
+# define EKF2_MAX_INSTANCES 9
+#endif
 
 using namespace time_literals;
 
@@ -84,6 +87,7 @@ private:
 
 	// Subscriptions (per estimator instance)
 	struct EstimatorInstance {
+
 		EstimatorInstance(EKF2Selector *selector, uint8_t i) :
 			estimator_attitude_sub{selector, ORB_ID(estimator_attitude), i},
 			estimator_status_sub{selector, ORB_ID(estimator_status), i},
@@ -119,13 +123,17 @@ private:
 	EstimatorInstance _instance[EKF2_MAX_INSTANCES] {
 		{this, 0},
 		{this, 1},
+#if EKF2_MAX_INSTANCES > 2
 		{this, 2},
 		{this, 3},
+#if EKF2_MAX_INSTANCES > 4
 		{this, 4},
 		{this, 5},
 		{this, 6},
 		{this, 7},
 		{this, 8},
+#endif
+#endif
 	};
 
 	static constexpr uint8_t IMU_STATUS_SIZE = (sizeof(sensors_status_imu_s::gyro_inconsistency_rad_s) / sizeof(
@@ -136,7 +144,7 @@ private:
 	static_assert(IMU_STATUS_SIZE == sizeof(estimator_selector_status_s::accumulated_accel_error) / sizeof(
 			      estimator_selector_status_s::accumulated_accel_error[0]),
 		      "increase estimator_selector_status_s::accumulated_accel_error size");
-	static_assert(EKF2_MAX_INSTANCES == sizeof(estimator_selector_status_s::combined_test_ratio) / sizeof(
+	static_assert(EKF2_MAX_INSTANCES <= sizeof(estimator_selector_status_s::combined_test_ratio) / sizeof(
 			      estimator_selector_status_s::combined_test_ratio[0]),
 		      "increase estimator_selector_status_s::combined_test_ratio size");
 

src/modules/logger/logged_topics.cpp

@@ -111,7 +111,7 @@ void LoggedTopics::add_default_topics()
 	add_topic("vehicle_status_flags");
 	add_topic("vtol_vehicle_status", 200);
 
-	// Control allocaton topics
+	// Control allocation topics
 	add_topic("vehicle_angular_acceleration_setpoint", 20);
 	add_topic("vehicle_angular_acceleration", 20);
 	add_topic("vehicle_thrust_setpoint", 20);
@@ -126,7 +126,12 @@ void LoggedTopics::add_default_topics()
 	add_topic_multi("telemetry_status", 1000, 4);
 
 	// EKF multi topics (currently max 9 estimators)
-	static constexpr uint8_t MAX_ESTIMATOR_INSTANCES = 4;
+#if CONSTRAINED_MEMORY
+	static constexpr uint8_t MAX_ESTIMATOR_INSTANCES = 2;
+#else
+	static constexpr uint8_t MAX_ESTIMATOR_INSTANCES = 6; // artificailly limited until PlotJuggler fixed
+#endif
+
 	add_topic("estimator_selector_status");
 	add_topic_multi("ekf_gps_drift", 1000, MAX_ESTIMATOR_INSTANCES);
 	add_topic_multi("estimator_attitude", 500, MAX_ESTIMATOR_INSTANCES);

src/modules/uORB/uORB.h

@@ -58,9 +58,13 @@ struct orb_metadata {
 typedef const struct orb_metadata *orb_id_t;
 
 /**
- * Maximum number of multi topic instances
+ * Maximum number of multi topic instances. This must be <= 10 (because it's the last char of the node path)
  */
-#define ORB_MULTI_MAX_INSTANCES	10 // This must be <= 10 (because it's the last char of the node path)
+#if defined(CONSTRAINED_MEMORY)
+# define ORB_MULTI_MAX_INSTANCES 4
+#else
+# define ORB_MULTI_MAX_INSTANCES 10
+#endif
 
 /**
  * Generates a pointer to the uORB metadata structure for

src/modules/uORB/uORB_tests/uORBTest_UnitTest.cpp

@@ -727,12 +727,14 @@ int uORBTest::UnitTest::test_SubscriptionMulti()
 		ORB_ID::orb_test,
 		ORB_ID::orb_test,
 		ORB_ID::orb_test,
+#if ORB_MULTI_MAX_INSTANCES > 4
 		ORB_ID::orb_test,
 		ORB_ID::orb_test,
 		ORB_ID::orb_test,
 		ORB_ID::orb_test,
 		ORB_ID::orb_test,
 		ORB_ID::orb_test,
+#endif
 	};
 
 	uORB::SubscriptionMultiArray<orb_test_s> orb_test_sub_multi_array{ORB_ID::orb_test};