AP_NavEKF2: Publish the primary EKF index

libraries/AP_NavEKF2/AP_NavEKF2.cpp

@@ -517,6 +517,18 @@ bool NavEKF2::healthy(void) const
     return core[primary].healthy();
 }
 
+// returns the index of the primary core
+// return false if no primary core selected
+bool NavEKF2::getPrimaryCoreIndex(uint8_t index) const
+{
+    if (!core) {
+        return false;
+    }
+    index = primary;
+    return true;
+}
+
+
 // Return the last calculated NED position relative to the reference point (m).
 // If a calculated solution is not available, use the best available data and return false
 // If false returned, do not use for flight control

libraries/AP_NavEKF2/AP_NavEKF2.h

@@ -57,6 +57,10 @@ public:
     // Check basic filter health metrics and return a consolidated health status
     bool healthy(void) const;
 
+    // returns the index of the primary core
+    // return false if no primary core selected
+    bool getPrimaryCoreIndex(uint8_t index) const;
+
     // Return the last calculated NED position relative to the reference point (m).
     // If a calculated solution is not available, use the best available data and return false
     // If false returned, do not use for flight control