diff --git a/df_datalink_sp/src/include/error.h b/df_datalink_sp/src/include/error.h
index f3acc6a..0b878d5 100644
--- a/df_datalink_sp/src/include/error.h
+++ b/df_datalink_sp/src/include/error.h
@@ -25,7 +25,7 @@
 /******************************************************************************/
 
 /**
- * @name ERRORNO)
+ * @name ERRORNO
  * @{
  */
 
diff --git a/df_datalink_sp/src/systembus/systembus.c b/df_datalink_sp/src/systembus/systembus.c
index efb32aa..524cd66 100644
--- a/df_datalink_sp/src/systembus/systembus.c
+++ b/df_datalink_sp/src/systembus/systembus.c
@@ -26,9 +26,13 @@
 #include "common.h"
 #include "error.h"
 #include "circ_queue.h"
-
 #include "../system_monitor.h"
 
+/**
+ * @addtogroup SystemBus_Protocol_Routine
+ * @{
+ */
+
 /************************** Constant Definitions *****************************/
 /**
  * @name SystemBus_MSG_Constants
@@ -498,64 +502,6 @@ static int32_t SystemBus_GenRemoteTestRsp(SYSBUS *instPtr, uint8_t *msg)
 	return SUCCESS;
 }
 
-/*****************************************************************************/
-/**
- * @brief   Initialize System Bus instance.
- *
- * @param   InstPtr A double pointer to System Bus instance.
- * @param   config  A pointer to System Bus configurations.
- *
- * @return  None.
- *
- ******************************************************************************/
-int32_t SystemBus_Init(SYSBUS **instPtr, SYSBUS_CONFIG *config)
-{
-	ASSERT(instPtr != NULL);
-	ASSERT(config != NULL);
-	SYSBUS_UART_CONFIG uartConfig;
-	int32_t Status;
-	(*instPtr) = malloc(sizeof(SYSBUS));
-	if ((*instPtr) == NULL)
-	{
-		return FAILURE;
-	}
-	(*instPtr)->rxQueue = NULL;
-	(*instPtr)->txQueue = NULL;
-	(*instPtr)->uartInst = NULL;
-	memcpy(&((*instPtr)->config), config, sizeof(SYSBUS_CONFIG));
-	memset(&((*instPtr)->sysbusLog), 0x00, sizeof(SYSBUSLOG));
-	memset(&((*instPtr)->linkLog), 0x00, sizeof(LINKLOG));
-	memset(&((*instPtr)->phyLog), 0x00, sizeof(PHYLOG));
-	memset(&((*instPtr)->hwState), 0x00, sizeof(HWSTATE));
-	uartConfig.baseAddr = config->baseAddr;
-	Status = SysbusUart_Init(&((*instPtr)->uartInst), &uartConfig);
-	if (Status != SUCCESS)
-	{
-		Status = ENOMEM;
-		goto sysbus_init_error;
-	}
-	if (CircQueueCreate(&((*instPtr)->txQueue), (*instPtr)->config.txQueueMax) == false)
-	{
-		Status = ENOMEM;
-		goto sysbus_init_error;
-	}
-	if (CircQueueCreate(&((*instPtr)->rxQueue), (*instPtr)->config.rxQueueMax) == false)
-	{
-		Status = ENOMEM;
-		goto sysbus_init_error;
-	}
-	(*instPtr)->isRxDone = false; // nothing received.
-	(*instPtr)->isTxDone = true;  // nothing to be sent.
-	return SUCCESS;
-
-sysbus_init_error:
-	free((*instPtr)->uartInst);
-	free((*instPtr)->txQueue);
-	free((*instPtr)->rxQueue);
-	free(*instPtr);
-	return Status;
-}
-
 /*****************************************************************************/
 /**
  * @brief   A handler function. This handler  evaluate the message from system
@@ -702,6 +648,66 @@ int32_t SystemBus_MakeResp(SYSBUS *instPtr)
 	return Status;
 }
 
+/** @} */
+
+/*****************************************************************************/
+/**
+ * @brief   Initialize System Bus instance.
+ *
+ * @param   InstPtr A double pointer to System Bus instance.
+ * @param   config  A pointer to System Bus configurations.
+ *
+ * @return  None.
+ *
+ ******************************************************************************/
+int32_t SystemBus_Init(SYSBUS **instPtr, SYSBUS_CONFIG *config)
+{
+	ASSERT(instPtr != NULL);
+	ASSERT(config != NULL);
+	SYSBUS_UART_CONFIG uartConfig;
+	int32_t Status;
+	(*instPtr) = malloc(sizeof(SYSBUS));
+	if ((*instPtr) == NULL)
+	{
+		return FAILURE;
+	}
+	(*instPtr)->rxQueue = NULL;
+	(*instPtr)->txQueue = NULL;
+	(*instPtr)->uartInst = NULL;
+	memcpy(&((*instPtr)->config), config, sizeof(SYSBUS_CONFIG));
+	memset(&((*instPtr)->sysbusLog), 0x00, sizeof(SYSBUSLOG));
+	memset(&((*instPtr)->linkLog), 0x00, sizeof(LINKLOG));
+	memset(&((*instPtr)->phyLog), 0x00, sizeof(PHYLOG));
+	memset(&((*instPtr)->hwState), 0x00, sizeof(HWSTATE));
+	uartConfig.baseAddr = config->baseAddr;
+	Status = SysbusUart_Init(&((*instPtr)->uartInst), &uartConfig);
+	if (Status != SUCCESS)
+	{
+		Status = ENOMEM;
+		goto sysbus_init_error;
+	}
+	if (CircQueueCreate(&((*instPtr)->txQueue), (*instPtr)->config.txQueueMax) == false)
+	{
+		Status = ENOMEM;
+		goto sysbus_init_error;
+	}
+	if (CircQueueCreate(&((*instPtr)->rxQueue), (*instPtr)->config.rxQueueMax) == false)
+	{
+		Status = ENOMEM;
+		goto sysbus_init_error;
+	}
+	(*instPtr)->isRxDone = false; // nothing received.
+	(*instPtr)->isTxDone = true;  // nothing to be sent.
+	return SUCCESS;
+
+sysbus_init_error:
+	free((*instPtr)->uartInst);
+	free((*instPtr)->txQueue);
+	free((*instPtr)->rxQueue);
+	free(*instPtr);
+	return Status;
+}
+
 /*****************************************************************************/
 /**
  * @brief   This function handles the systembus tx irq events.
diff --git a/df_datalink_sp/src/systembus/systembus.h b/df_datalink_sp/src/systembus/systembus.h
index 76c0b81..d5eafdc 100644
--- a/df_datalink_sp/src/systembus/systembus.h
+++ b/df_datalink_sp/src/systembus/systembus.h
@@ -61,8 +61,13 @@ typedef struct
 
 int32_t SystemBus_Init(SYSBUS **instPtr, SYSBUS_CONFIG *config);
 
+/**
+ * @defgroup SystemBus_Protocol_Routine
+ * @{
+ */
 int32_t SystemBus_HandleCmd(SYSBUS *instPtr);
 int32_t SystemBus_MakeResp(SYSBUS *instPtr);
+/** @} */
 
 int32_t SystemBus_TxIntrHandler(SYSBUS *instPtr);
 int32_t SystemBus_RxIntrHandler(SYSBUS *instPtr);