diff --git a/common/app/app.h b/common/app/app.h
index 2777516..71d43b8 100644
--- a/common/app/app.h
+++ b/common/app/app.h
@@ -1,12 +1,10 @@
+#ifndef APP_H
+#define APP_H
+
 /**
  * @defgroup app Application
  * The App Module contains the effective, platform independent application.
  */
-
-
-/**
- * @addtogroup app
- */
 /*@{*/
 
 /**
@@ -21,10 +19,7 @@ void app_init();
  */
 void app_process();
 
-/**
- * @defgroup screens Screens
- * The Screens of the application. \sa Screen
- */
-
 
 /*@}*/
+
+#endif /* APP_H */
diff --git a/common/app/screen_main.h b/common/app/screen_main.h
index 4f25955..1be9ea9 100644
--- a/common/app/screen_main.h
+++ b/common/app/screen_main.h
@@ -1,5 +1,17 @@
 #include "screen.h"
 
+/**
+ * @addtogroup app
+ */
+/*@{*/
+
+/**
+ * @defgroup screens Screens
+ * The Screens of the application. \sa Screen
+ */
+/*@}*/
+
+
 /**
  * @addtogroup screens
  */
diff --git a/common/gui/button.h b/common/gui/button.h
index e451943..b8c6a98 100644
--- a/common/gui/button.h
+++ b/common/gui/button.h
@@ -1,6 +1,19 @@
 #ifndef BUTTON_H
 #define BUTTON_H
 
+/**
+ * @defgroup gui Gui
+ * The Gui Module
+ */
+/*@{*/
+
+/**
+ * @defgroup button Button
+ * The Button Gui-Element
+ */
+/*@{*/
+
+
 
 #include "touch.h"
 
@@ -39,6 +52,6 @@ void guiRemoveBitmapButton(BITMAPBUTTON_STRUCT* button);
 void guiRedrawBitmapButton(BITMAPBUTTON_STRUCT* button);
 */
 
-
+/*@}@}*/
 
 #endif /* BUTTON_H */
diff --git a/common/gui/checkbox.h b/common/gui/checkbox.h
index 1a063ab..7b1b8e2 100644
--- a/common/gui/checkbox.h
+++ b/common/gui/checkbox.h
@@ -1,3 +1,17 @@
+#ifndef CHECKBOX_H
+#define CHECKBOX_H
+
+/**
+ * @addtogroup gui
+ */
+/*@{*/
+
+/**
+ * @defgroup checkbox Checkbox
+ * The Checkbox Gui-Element
+ */
+/*@{*/
+
 
 typedef void (*CHECKBOX_CALLBACK)(void *checkbox, bool checked);	//!< Function pointer used...
 typedef struct {
@@ -13,3 +27,7 @@ void gui_checkbox_remove(CHECKBOX_STRUCT* checkbox);
 void gui_checkbox_update(CHECKBOX_STRUCT* checkbox);
 void gui_checkbox_redraw(CHECKBOX_STRUCT* checkbox);
 #define CHECKBOX_WIN_FG_COLOR RGB(32,161,34)
+
+/*@}@}*/
+
+#endif /* CHECKBOX_H */
diff --git a/common/gui/numupdown.h b/common/gui/numupdown.h
index 09a4abb..fd97667 100644
--- a/common/gui/numupdown.h
+++ b/common/gui/numupdown.h
@@ -1,3 +1,18 @@
+#ifndef NUMUPDOWN_H
+#define NUMUPDOWN_H
+
+/**
+ * @addtogroup gui
+ */
+/*@{*/
+
+/**
+ * @defgroup numupdown NummericUpDown
+ * The NummericUpDown Gui Element
+ */
+/*@{*/
+
+
 #include "button.h"
 
 typedef void (*NUMUPDOWN_CALLBACK)(void *numupdown, int16_t value);	//!< Function pointer used...
@@ -20,3 +35,7 @@ bool gui_numupdown_add(NUMUPDOWN_STRUCT* numupdown);
 void gui_numupdown_remove(NUMUPDOWN_STRUCT* numupdown);
 void gui_numupdown_update(NUMUPDOWN_STRUCT* numupdown);
 void gui_numupdown_redraw(NUMUPDOWN_STRUCT* numupdown);
+
+/*@}@}*/
+
+#endif /* NUMUPDOWN_H */
diff --git a/common/gui/screen.h b/common/gui/screen.h
index 375ccbf..a1e8a32 100644
--- a/common/gui/screen.h
+++ b/common/gui/screen.h
@@ -1,6 +1,16 @@
 #ifndef SCREEN_H
 #define SCREEN_H
 
+/**
+ * @addtogroup gui
+ */
+/*@{*/
+
+/**
+ * @defgroup screen Screen
+ * The Screen Submodule
+ */
+/*@{*/
 
 #include <stdio.h>
 #include <stdbool.h>
@@ -30,4 +40,6 @@ SCREEN_STRUCT* gui_screen_get_current();
 //Updates/switches the screens. Call this from the app main loop, as fast as you can.
 void gui_screen_update();
 
+/*@}@}*/
+
 #endif /* SCREEN_H */
diff --git a/common/system/system.h b/common/system/system.h
index 62b6720..31f7bc9 100644
--- a/common/system/system.h
+++ b/common/system/system.h
@@ -1,7 +1,38 @@
+#ifndef SYSTEM_H
+#define SYSTEM_H
+
+/**
+ * @defgroup system System
+ * The System Module provides access to delay functions, leds and provides a system init function
+ */
+/*@{*/
+
+
 #include <stdbool.h>
 #include <stdint.h>
 
+/**
+ * Initializes the system. Call this method at the start of your app_init() function and before using any system_* functions
+ * @return true on success
+ */
 bool system_init();
+
+/**
+ * Sleeps for a certain amount of time
+ * @param msec The number of milliseconds to sleep
+ */
 void system_delay(uint32_t msec);
+
+/**
+ * Executes pending system events (like handling usb, timers etc). Call this somewhere in app_process().
+ */
 void system_process();
+
+/**
+ * Toggles a Status Led. Use this function for debugging or to show activity
+ */
 void system_toggle_led();
+
+/*@}*/
+
+#endif /* SYSTEM_H */
diff --git a/common/tft/tft.h b/common/tft/tft.h
index 2d13b0e..ea3897b 100644
--- a/common/tft/tft.h
+++ b/common/tft/tft.h
@@ -1,3 +1,5 @@
+#ifndef TFT_H
+#define TFT_H
 
 /**
  * @defgroup tft TFT
@@ -150,3 +152,5 @@ void tft_print_line(uint16_t x, uint16_t y, uint16_t color, uint16_t bgcolor, ui
 void tft_print_formatted(uint16_t x, uint16_t y, uint16_t color, uint16_t bgcolor, uint8_t font, const char* format, ...);
 
 /*@}*/
+
+#endif /* TFT_H */
diff --git a/common/touch/touch.h b/common/touch/touch.h
index 7df8fd2..08eecb1 100644
--- a/common/touch/touch.h
+++ b/common/touch/touch.h
@@ -1,3 +1,5 @@
+#ifndef TOUCH_H
+#define TOUCH_H
 
 /**
  * @defgroup touch Touch
@@ -11,9 +13,6 @@
 /*@{*/
 
 
-#ifndef TOUCH_H
-#define TOUCH_H
-
 #include<stdbool.h>
 #include<stdint.h>
 
@@ -108,6 +107,6 @@ void touch_unregister_area(TOUCH_AREA_STRUCT* area);
 POINT_STRUCT touch_get_last_point();
 
 
-#endif /* TOUCH_H */
-
 /*@}*/
+
+#endif /* TOUCH_H */