AP_Rangefinder: fixed param handling for Wasp backends

libraries/AP_RangeFinder/RangeFinder.cpp

@@ -539,6 +539,8 @@ const AP_Param::GroupInfo RangeFinder::var_info[] = {
     AP_GROUPEND
 };
 
+const AP_Param::GroupInfo *RangeFinder::backend_var_info[RANGEFINDER_MAX_INSTANCES];
+
 RangeFinder::RangeFinder(AP_SerialManager &_serial_manager, enum Rotation orientation_default) :
     num_instances(0),
     estimated_terrain_height(0),
@@ -739,6 +741,12 @@ void RangeFinder::detect_instance(uint8_t instance, uint8_t& serial_instance)
     default:
         break;
     }
+
+    // if the backend has some local parameters then make those available in the tree
+    if (drivers[instance] && state[instance].var_info) {
+        backend_var_info[instance] = state[instance].var_info;
+        AP_Param::load_object_from_eeprom(drivers[instance], backend_var_info[instance]);
+    }
 }
 
 AP_RangeFinder_Backend *RangeFinder::get_backend(uint8_t id) const {

libraries/AP_RangeFinder/RangeFinder.h

@@ -101,9 +101,11 @@ public:
         AP_Int8  address;
         AP_Vector3f pos_offset; // position offset in body frame
         AP_Int8  orientation;
-        const struct AP_Param::GroupInfo *backend_var_info;
+        const struct AP_Param::GroupInfo *var_info;
     };
 
+    static const struct AP_Param::GroupInfo *backend_var_info[RANGEFINDER_MAX_INSTANCES];
+    
     AP_Int16 _powersave_range;
 
     // parameters for each instance