diff --git a/drivers/afio.h b/drivers/afio.h
index 961390c..f1a06de 100644
--- a/drivers/afio.h
+++ b/drivers/afio.h
@@ -19,6 +19,13 @@
 
 //--functions-------------------------------------------------------------------
 
+/**
+ * Maps the exti lines to gpio ports. The ExtiLine enum can be used as a
+ * mask to configure multiple lines at the same time. This function is used by
+ * the exti module to configure its line and calling it directly should should
+ * thus normaly not be needed. It could however still be usefull when wanting to
+ * change the port linked to an exti without reconfiguring it entirely
+ */
 void afio_map_exti(enum ExtiLine line_mask, enum GpioPort port);
 
 
diff --git a/drivers/exti.h b/drivers/exti.h
index d2c5089..3349aca 100644
--- a/drivers/exti.h
+++ b/drivers/exti.h
@@ -71,7 +71,10 @@ typedef void (*ExtiCallback)(void);
  * exti 1). When possible, it is recommanded to use the lowest id possible for
  * better performance. The ExtiConfig enum can be used as mask. If no callback
  * is specified, the interrupt won't be enabled, but an event will still be sent
- * to wake the cpu up
+ * to wake the cpu up.
+ *
+ * Note: wich port is linked to a line can be changed atfer the fact using
+ * afio_map_exti()
  */
 void exti_configure(enum ExtiLine line_mask, enum GpioPort port,
 		enum ExtiConfig config_mask, ExtiCallback callback);