AP_Camera: Support for camera feedback signal

Added _feedback_pin;
Added _camera_triggered;
Included FEEDBACK_PIN parameter and his default definition

libraries/AP_Camera/AP_Camera.cpp

@@ -71,6 +71,13 @@ const AP_Param::GroupInfo AP_Camera::var_info[] = {
     // @Units: Degrees
     // @Range: 0 180
     AP_GROUPINFO("MAX_ROLL",  7, AP_Camera, _max_roll, 0),
+ 
+    // @Param: FEEDBACK_PIN
+    // @DisplayName: Camera feedback pin
+    // @Description: pin number to use for save accurate camera feedback messages. If set to -1 then don't use a pin flag for this, otherwise this is a pin number which if held high after a picture trigger order, will save camera messages when camera really takes a picture. An universal camera hot shoe is needed
+    // @Values: -1:Disabled, 0-8:APM FeedbackPin, 50-55:PixHawk FeedbackPin
+    // @User: Standard
+    AP_GROUPINFO("FEEDBACK_PIN",  8, AP_Camera, _feedback_pin, AP_CAMERA_FEEDBACK_DEFAULT_FEEDBACK_PIN),
 
     AP_GROUPEND
 };
@@ -276,4 +283,4 @@ bool AP_Camera::update_location(const struct Location &loc, const AP_AHRS &ahrs)
         _last_photo_time = tnow;
         return true;
     }
-}
+}

libraries/AP_Camera/AP_Camera.h

@@ -25,6 +25,8 @@
 #define AP_CAMERA_SERVO_ON_PWM              1300    // default PWM value to move servo to when shutter is activated
 #define AP_CAMERA_SERVO_OFF_PWM             1100    // default PWM value to move servo to when shutter is deactivated
 
+#define AP_CAMERA_FEEDBACK_DEFAULT_FEEDBACK_PIN -1  // default is to not use camera feedback pin
+
 /// @class	Camera
 /// @brief	Object managing a Photo or video camera
 class AP_Camera {
@@ -40,6 +42,12 @@ public:
         _apm_relay = obj_relay;
     }
 
+    // pin number for accurate camera feedback messages
+    AP_Int8         _feedback_pin;
+    
+    // this is set to 1 when camera really has been triggered    
+    AP_Int8         _camera_triggered;
+    
     // single entry point to take pictures
     //  set send_mavlink_msg to true to send DO_DIGICAM_CONTROL message to all components
     void            trigger_pic(bool send_mavlink_msg);
@@ -85,4 +93,4 @@ private:
 
 };
 
-#endif /* AP_CAMERA_H */
+#endif /* AP_CAMERA_H */