AP_Beacon_Marvelmind: Record the timestamp once, on success.

libraries/AP_Beacon/AP_Beacon_Marvelmind.cpp

@@ -366,6 +366,7 @@ bool AP_Beacon_Marvelmind::healthy()
 
 void AP_Beacon_Marvelmind::set_stationary_beacons_positions()
 {
+    bool set = false;
     if (vehicle_position_initialized && beacon_position_initialized) {
         if (hedge._have_new_values) {
             vehicle_position_NED__m = Vector3f(hedge.cur_position.y__mm * 0.001f,
@@ -373,6 +374,7 @@ void AP_Beacon_Marvelmind::set_stationary_beacons_positions()
                                               -hedge.cur_position.z__mm * 0.001f); //Transform Marvelmind ENU to Ardupilot NED
             //TODO: Calculate Accuracy of the received signal. Marvelmind *advertises* +/- 2cms
             set_vehicle_position(vehicle_position_NED__m, 0.02f);
+            set = true;
             Debug(2,
                   "Hedge is at N%.2f, E%.2f, D%.2f",
                   vehicle_position_NED__m[0],
@@ -386,6 +388,7 @@ void AP_Beacon_Marvelmind::set_stationary_beacons_positions()
                                                      hedge.positions_beacons.beacons[i].x__mm * 0.001f,
                                                     -hedge.positions_beacons.beacons[i].z__mm * 0.001f); //Transform Marvelmind ENU to Ardupilot NED
                 set_beacon_position(i, beacon_position_NED__m[i]);
+                set = true;
                 Debug(2,
                       "Beacon %d is at N%.2f, E%.2f, D%.2f",
                       i,
@@ -397,6 +400,8 @@ void AP_Beacon_Marvelmind::set_stationary_beacons_positions()
         hedge.positions_beacons.updated = false;
 
     }
+    if (set) {
+        last_update_ms = AP_HAL::millis();
     }
 }