Index: sources/canbus/messagehandler.h
===================================================================
diff -u -r1732e83d2a0308b9c706f37d6d7724a364bbff2a -rfee7fabf49befb065c89248c19e15efc9ca194e4
--- sources/canbus/messagehandler.h	(.../messagehandler.h)	(revision 1732e83d2a0308b9c706f37d6d7724a364bbff2a)
+++ sources/canbus/messagehandler.h	(.../messagehandler.h)	(revision fee7fabf49befb065c89248c19e15efc9ca194e4)
@@ -1,14 +1,10 @@
 /*!
  *
- * Copyright (c) 2019-2020 Diality Inc. - All Rights Reserved.
+ * Copyright (c) 2019-2019 Diality Inc. - All Rights Reserved.
  * copyright
-
  *          THIS CODE MAY NOT BE COPIED OR REPRODUCED IN ANY FORM,
-
  *          IN PART OR IN WHOLE,
-
  *          WITHOUT THE EXPLICIT PERMISSION OF THE COPYRIGHT OWNER.
-
  *
  * file    messagehandler.h
  * date    10/26/2019
@@ -38,18 +34,28 @@
 using namespace Gui;
 namespace Can {
 
+/*!
+ * \brief   The MessageHandler class                                                    \n
+ * \details This class is an adapter or translator from QByteArray and QCanBusFrame     \n
+ *          So this class gets the data for the frame as QByteArray and creates a frame \n
+ *          and send it to the CanInterface to deal with the CANBUS.                    \n
+ */
 class MessageHandler : public QObject
 {
     Q_OBJECT
 
     // friends
     friend class ::unittests;
 
+    /*!
+     * \brief   The ChannelGroup enum
+     * \details The enum which represent the categories of the CANBUS channel
+     */
     enum class ChannelGroup {
-        eChannel_Unknown,
-        eChannel_Ignores,
-        eChannel_Listens,
-        eChannel_Outputs,
+        eChannel_Unknown, ///< An Unknown channels category
+        eChannel_Ignores, ///< The Channels which will be ignored by UI
+        eChannel_Listens, ///< The Channels that UI is listening to
+        eChannel_Outputs, ///< The Channels that are related to UI frames out.
     };
 
     // Singleton
@@ -59,17 +65,37 @@
 
 private:
     void initConnections();
-
     void transmitFrame(Can_Id vCan_Id, const QByteArray &vData = 0);
-
     ChannelGroup checkChannel(quint32 vFrameId, bool *vOK = nullptr);
 
 private slots: // Should be private for thread safety and is connected internally.
     void  onFrameTransmit(Can_Id vCan_ID, const QByteArray   &vData   ); // GUI => CAN
     void  onFrameReceive (                const QCanBusFrame &vFrame  ); // GUI <= CAN
 
 signals:
-    void didFrameReceive (Can_Id vCan_ID, const QByteArray   &vPayload); // GUI <= CAN
+    /*!
+     * \brief   didFrameReceive
+     * \details After CanInterface receives a frame notifies MessageHandler
+     *          by emitting CanInterface::didFrameReceive signal,
+     *          then Message Handler calls its slot MessageHandler::onFrameReceive to handle the message,
+     *          And when the message has been processed vCan_Id of type Can_Id which is the Channel ID of the frame
+     *          and vPayload of the frame of type QByteArray has been extracted,
+     *          This signal will be emitted to notify MessageDispatcher to start collecting data
+     *          for this message over this channel.
+     * \param   vCan_ID  - Channel Id of the frame.
+     * \param   vPayload - Payload of the frame.
+     */
+    void didFrameReceive (Can_Id vCan_Id, const QByteArray   &vPayload); // GUI <= CAN
+
+    /*!
+     * \brief   didFrameTransmit
+     * \details After MessageDispatcher requests MessageHandler to transmit a message,
+     *          And MessageHandler calls its slot MessageHandler::onFrameTransmit to handle the message,
+     *          And when the message has been processed and a Frame has been created,
+     *          this signal will be emitted to notify CanInterface to send the frame.
+     * \ref     CanInterface::onFrameTransmit
+     * \param vFrame - The frame which has been created to be transmitted.
+     */
     void didFrameTransmit(                const QCanBusFrame &vFrame  ); // GUI => CAN
 };
 }