Notify: add Lost Copter tone

libraries/AP_Notify/AP_Notify.h

@@ -72,6 +72,7 @@ public:
 
         // additional flags
         uint32_t external_leds      : 1;    // 1 if external LEDs are enabled (normally only used for copter)
+        uint32_t lost_copter        : 1;    // 1 when lost copter tone is requested (normally only used for copter)
     };
 
     /// notify_events_type - bitmask of active events.

libraries/AP_Notify/ToneAlarm_PX4.cpp

@@ -230,6 +230,17 @@ void ToneAlarm_PX4::update()
             play_tone(AP_NOTIFY_PX4_TONE_LOUD_ATTENTION_NEEDED);
         }
     }
+
+
+    if (flags.lost_copter != AP_Notify::flags.lost_copter) {
+        flags.lost_copter = AP_Notify::flags.lost_copter;
+        if(flags.lost_copter) {
+            play_tone(AP_NOTIFY_PX4_TONE_LOUD_LOST_COPTER_CTS);
+        }else{
+            stop_cont_tone();
+        }
+    }
+
 }
 
 #endif // CONFIG_HAL_BOARD == HAL_BOARD_PX4

libraries/AP_Notify/ToneAlarm_PX4.h

@@ -54,6 +54,7 @@ private:
         uint8_t parachute_release     : 1;    // 1 if parachute is being released
         uint8_t pre_arm_check         : 1;    // 0 = failing checks, 1 = passed
         uint8_t failsafe_radio        : 1;    // 1 if radio failsafe
+        uint8_t lost_copter           : 1;    // 1 if lost copter tone requested
     } flags;
 
     int8_t _cont_tone_playing;