fix HID headers

facchinm · cmaglie · commit 41254db5361c · 2015-07-16T13:13:51.000+02:00
diff --git a/Keyboard.h b/Keyboard.h
@@ -19,6 +19,9 @@
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
 
+#ifndef KEYBOARD_h
+#define KEYBOARD_h
+
 #if defined(_USING_HID)
 
 #error "Can only attach one submodule to HID module"
