Index: firmware/App/Services/SystemComm.h
===================================================================
diff -u -ra303cd4258157a8fbcbd8af4dd2bbaadec1a736c -r7d4711edd7b40cd3e29f43e766f79a8a09586fe9
--- firmware/App/Services/SystemComm.h	(.../SystemComm.h)	(revision a303cd4258157a8fbcbd8af4dd2bbaadec1a736c)
+++ firmware/App/Services/SystemComm.h	(.../SystemComm.h)	(revision 7d4711edd7b40cd3e29f43e766f79a8a09586fe9)
@@ -1,41 +1,65 @@
-/**************************************************************************
- *
- *  Copyright (c) 2019-2020 Diality Inc. - All Rights Reserved.
- *
- *  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 SystemComm.h
- *
- *  @date 08-Oct-2019
- *  @author S. Nash
- *
- *  @brief header file for System Communication service .
- *
- **************************************************************************/
+/**************************************************************************
+*
+* Copyright (c) 2019-2024 Diality Inc. - All Rights Reserved.
+*
+* 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    SystemComm.h
+*
+* @author  (last)      Michael Garthwaite
+* @date    (last)      17-Aug-2023
+*
+* @author  (original)  Dara Navaei
+* @date    (original)  05-Nov-2019
+*
+***************************************************************************/
 
 #ifndef __SYSTEM_COMM_H__
 #define __SYSTEM_COMM_H__
 
-#include "Common.h"
+#include "DGCommon.h"
 #include "CommBuffers.h"
+#include "MsgQueues.h"
 
+/**
+ *  @defgroup SystemComm SystemComm
+ *  @brief System communication module. Manages incoming and outgoing CAN frames.
+ *
+ *  @addtogroup SystemComm
+ *  @{
+ */
+
 // ********** public definitions **********
 
-#define MESSAGE_SYNC_BYTE           0xA5
+#define MESSAGE_SYNC_BYTE                       0xA5                                                                ///< Denali message syncronization byte.
 
-#define CAN_MESSAGE_PAYLOAD_SIZE    8
-#define PC_MESSAGE_PACKET_SIZE      8
+#define CAN_MESSAGE_PAYLOAD_SIZE                8                                                                   ///< CAN frame payload size (in bytes).
 
-typedef COMM_BUFFER_T   CAN_MESSAGE_BOX_T;       // the first 10 comm buffers align with the 10 active CAN message boxes
+#define MSG_ID_ACK_MESSAGE_THAT_REQUIRES_ACK    0xFFFF                                                              ///< Denali message ID for acknowledging received messages (when required).
+#define MSG_ACK_BIT                             0x8000                                                              ///< ACK bit in sequence number that indicates an ACK is required.
+#define MAX_MSG_SEQ_NO                          0x7FFF                                                              ///< Maximum sequence number for Denali message (then wraps to 1).
+#define MIN_MSG_SEQ_NO                          0x0001                                                              ///< Minimum sequence number for Denali message.
+#define MAX_ACK_MSG_SIZE                        ( sizeof( MESSAGE_WRAPPER_T ) + 1 + CAN_MESSAGE_PAYLOAD_SIZE )      ///< Maximum size (in bytes) of Denali message including full (wrapped) message + sync + any CAN padding)
+
+typedef COMM_BUFFER_T   CAN_MESSAGE_BOX_T;                                                                          ///< the CAN comm buffers align with the active CAN message boxes
 
 // ********** public function prototypes **********
 
 void initSystemComm( void );
 void execSystemCommRx( void );
 void execSystemCommTx( void );
 void handleCANMsgInterrupt( CAN_MESSAGE_BOX_T srcCANBox );
-void handleUARTMsgRecvPacketInterrupt( void );
-void handleUARTMsgXmitPacketInterrupt( void );
+BOOL isCANBoxForXmit( CAN_MESSAGE_BOX_T srcCANBox );
+BOOL isCANBoxForRecv( CAN_MESSAGE_BOX_T srcCANBox );
+BOOL isHDCommunicating( void );
+BOOL isDGOnlyCANNode( void );
+BOOL addMsgToPendingACKList( MESSAGE_T *msg, COMM_BUFFER_T channel, U08 *msgData, U32 len );
+BOOL testSetHDCommunicationStatus( U32 value );
+BOOL testResetHDCommuncationStatus( void );
+BOOL testSetPendingACKOverride( U32 value );
+BOOL testResetPendingACKOverride( void );
+
+/**@}*/
 
 #endif