Index: firmware/App/Controllers/BalancingChamber.c
===================================================================
diff -u -r2a1296e1269e7c36dd07cb0f39b70b742f6de405 -r977f03e20990ed5579160b9b927df1c0f2428101
--- firmware/App/Controllers/BalancingChamber.c	(.../BalancingChamber.c)	(revision 2a1296e1269e7c36dd07cb0f39b70b742f6de405)
+++ firmware/App/Controllers/BalancingChamber.c	(.../BalancingChamber.c)	(revision 977f03e20990ed5579160b9b927df1c0f2428101)
@@ -846,6 +846,19 @@
 
 /*********************************************************************//**
  * @brief
+ * The getBalChamberSwitchingPeriod function gets the balancing chamber
+ * switching period.
+ * @details \b Inputs: balChamberSwitchingPeriod
+ * @details \b Outputs: none
+ * @return balancing chamber switching period
+ *************************************************************************/
+U32 getBalChamberSwitchingPeriod( void )
+{
+    return balChamberSwitchingPeriod;
+}
+
+/*********************************************************************//**
+ * @brief
  * The getBalChamberDataPublishInterval function gets the balancing chamber
  * data publish interval.
  * @details \b Inputs: balChamberDataPublishInterval
Index: firmware/App/Controllers/BalancingChamber.h
===================================================================
diff -u -rb13fc4db3591da73c3c63e81a69be3f9d0de2c3f -r977f03e20990ed5579160b9b927df1c0f2428101
--- firmware/App/Controllers/BalancingChamber.h	(.../BalancingChamber.h)	(revision b13fc4db3591da73c3c63e81a69be3f9d0de2c3f)
+++ firmware/App/Controllers/BalancingChamber.h	(.../BalancingChamber.h)	(revision 977f03e20990ed5579160b9b927df1c0f2428101)
@@ -68,6 +68,7 @@
 void valveControlForBCFreshSideOnlyOpenState( void );                    // Open only fresh side balancing chamber valves
 BOOL getBalChamberSwitchingOnlyStatus( void );                           // Get balancing chamber switching only status
 void setBalChamberSwitchingOnlyStatus( BOOL OnOff );                     // Set balancing chamber switching only status
+U32 getBalChamberSwitchingPeriod( void );                                // Get balancing chamber switching period
 
 BOOL testDDBalChamberDataPublishIntervalOverride( MESSAGE_T *message );  // To override the balancing chamber data publish interval
 BOOL testBalChamberSwFreqOverride( MESSAGE_T *message );                 // To override the balancing chamber switching frequency
Index: firmware/App/DDCommon.h
===================================================================
diff -u -r2a1296e1269e7c36dd07cb0f39b70b742f6de405 -r977f03e20990ed5579160b9b927df1c0f2428101
--- firmware/App/DDCommon.h	(.../DDCommon.h)	(revision 2a1296e1269e7c36dd07cb0f39b70b742f6de405)
+++ firmware/App/DDCommon.h	(.../DDCommon.h)	(revision 977f03e20990ed5579160b9b927df1c0f2428101)
@@ -54,6 +54,9 @@
 //Uncomment below once characterization/study completed
 //#define ENABLE_ALARM_2
 
+//Uncomment below for spent chamber filling
+#define __SPENT_CHAMBER_FILL__    1
+
 //Uncomment below if balancing chamber pressure alarm is required
 #define __BC_PRESSURE_ALARM__     1
 
Index: firmware/App/Modes/ModeGenDialysate.c
===================================================================
diff -u -r573a26b2a0273a4983b1de1cbff5bed63e01dce0 -r977f03e20990ed5579160b9b927df1c0f2428101
--- firmware/App/Modes/ModeGenDialysate.c	(.../ModeGenDialysate.c)	(revision 573a26b2a0273a4983b1de1cbff5bed63e01dce0)
+++ firmware/App/Modes/ModeGenDialysate.c	(.../ModeGenDialysate.c)	(revision 977f03e20990ed5579160b9b927df1c0f2428101)
@@ -28,6 +28,7 @@
 #include "OperationModes.h"
 #include "PersistentAlarm.h"
 #include "Pressure.h"
+#include "SpentChamberFill.h"
 #include "TaskGeneral.h"
 #include "TDInterface.h"
 #include "Temperature.h"
@@ -87,10 +88,9 @@
 static DD_GEND_MODE_STATE_T handleGenDDialysateBypassState( void );
 static DD_GEND_MODE_STATE_T handleGenDDialysateDeliveryState( void );
 static DD_GEND_MODE_STATE_T handleGenDDialysateDeliveryPauseState( void );
-static DD_GEND_MODE_STATE_T handleGenDDialysateIsolatedUFState( void );
-static F32 getGenDialysateTargetTemperature( void );
+static DD_GEND_MODE_STATE_T handleGenDSpentChamberFillState(void);
+static DD_GEND_MODE_STATE_T handleGenDIsolatedUFState( void );
 static void checkDialysateTemperature( void );
-static void calculateTargetDialysateTemp( void );
 static void publishGenDialysateModeData( void );
 
 /*********************************************************************//**
@@ -319,12 +319,16 @@
                 genDialysateState = handleGenDDialysateDeliveryState();
                 break;
 
+            case DD_GEND_SPENT_CHAMBER_FILL_STATE:
+                 genDialysateState = handleGenDSpentChamberFillState();
+                 break;
+
             case DD_GEND_DIALYSATE_DELIVERY_PAUSE:
                 genDialysateState = handleGenDDialysateDeliveryPauseState();
                 break;
 
             case DD_GEND_ISOLATED_UF_STATE:
-                genDialysateState = handleGenDDialysateIsolatedUFState();
+                genDialysateState = handleGenDIsolatedUFState();
                 break;
 
             default:
@@ -383,7 +387,7 @@
  * @details \b Outputs: Adjusted Target temperature
  * @return none.
  *************************************************************************/
-static void calculateTargetDialysateTemp( void )
+void calculateTargetDialysateTemp( void )
 {
     // Get the dialysate flow rate from TD
     F32 dialFlowrate = getTDDialysateFlowrate();
@@ -414,7 +418,7 @@
  * @details \b Outputs: none
  * @return the current state of gen dialysate mode
  *************************************************************************/
-static DD_GEND_MODE_STATE_T handleGenDDialysateIsolatedUFState( void )
+static DD_GEND_MODE_STATE_T handleGenDIsolatedUFState( void )
 {
     DD_GEND_MODE_STATE_T state  = DD_GEND_ISOLATED_UF_STATE;
 
@@ -491,7 +495,37 @@
 
     return state;
 }
+/*********************************************************************//**
+ * @brief
+ * The handleGenDSpentChamberFillState function performing spent
+ * chamber filling/degassing by executing balancing chamber.
+ * @details \b Inputs: none
+ * @details \b Outputs: balancing chamber state.
+ * @return the current state of gen dialysate mode
+ *************************************************************************/
+static DD_GEND_MODE_STATE_T handleGenDSpentChamberFillState( void )
+{
+    DD_GEND_MODE_STATE_T state  = DD_GEND_SPENT_CHAMBER_FILL_STATE;
 
+    LEVEL_STATE_T spentChamberLevel = getLevelStatus( D46_LEVL );
+
+    // High level is met
+    if ( LEVEL_STATE_HIGH == spentChamberLevel )
+    {
+        setModeGenDStateTransition( DD_GEND_DIALYSATE_BYPASS_STATE );
+        isDialDeliveryInProgress.data = FALSE;
+        state = DD_GEND_DIALYSATE_BYPASS_STATE;
+    }
+    else
+    {
+        //Execute Spent chamber fill
+        execSpentChamberFillControl();
+    }
+
+    return state;
+
+}
+
 /*********************************************************************//**
  * @brief
  * The requestDDGenDialyasteStop function handles an TD request to stop
@@ -644,7 +678,7 @@
  * @details \b Outputs: none
  * @return the target dialysate temperature for the treatment.
  *************************************************************************/
-static F32 getGenDialysateTargetTemperature( void )
+F32 getGenDialysateTargetTemperature( void )
 {
     F32 temp = getF32OverrideValue( &targetHydChamberFluidTemp );
 
Index: firmware/App/Modes/ModeGenDialysate.h
===================================================================
diff -u -rf6fb03f1e20395a61a5d5996f11f802ab8eacb2f -r977f03e20990ed5579160b9b927df1c0f2428101
--- firmware/App/Modes/ModeGenDialysate.h	(.../ModeGenDialysate.h)	(revision f6fb03f1e20395a61a5d5996f11f802ab8eacb2f)
+++ firmware/App/Modes/ModeGenDialysate.h	(.../ModeGenDialysate.h)	(revision 977f03e20990ed5579160b9b927df1c0f2428101)
@@ -33,6 +33,7 @@
 
 #define FRESH_DIAL_PUMP_INITIAL_RPM             2500                                        ///< Nominal RPM target for fresh dialysate pump to maintain required pressure.
 #define SPENT_DIAL_PUMP_INITIAL_RPM             2300                                        ///< Nominal RPM target for spent dialysate pump to maintain required pressure.
+#define SPENT_DIAL_PUMP_FILL_RPM                1500                                        ///< Nominal RPM target for spent chamber fill operations.
 
 /// Generate dialysate mode data structure
 typedef struct
@@ -61,6 +62,8 @@
 void setTreatmentParamUpdate( void );                       // To indicate one or more treatment parameters updated
 void updateTreatmentSettings( void );                       // Process the recent treatment parameters changes
 BOOL requestDDGenDialyasteStop( void );                     // Stop generate dialysate
+void calculateTargetDialysateTemp( void );                  // Update target dialysate temmperature with Delta Temp
+F32 getGenDialysateTargetTemperature( void );               // Get the target dialysate temperature
 
 BOOL testDDGenDialysateDataPublishIntervalOverride( MESSAGE_T *message );   // GenD Mode data publish interval override
 BOOL testDialDeliveryInProgressOverride( MESSAGE_T *message );              // To override the dialysate delivery in progress flag
Index: firmware/App/Services/AlarmMgmtSWFaults.h
===================================================================
diff -u -r4b09605126f35b80406e95d079f3822c51a3ba25 -r977f03e20990ed5579160b9b927df1c0f2428101
--- firmware/App/Services/AlarmMgmtSWFaults.h	(.../AlarmMgmtSWFaults.h)	(revision 4b09605126f35b80406e95d079f3822c51a3ba25)
+++ firmware/App/Services/AlarmMgmtSWFaults.h	(.../AlarmMgmtSWFaults.h)	(revision 977f03e20990ed5579160b9b927df1c0f2428101)
@@ -138,6 +138,7 @@
     SW_FAULT_ID_PRE_GEND_WET_SELF_TEST_INVALID_EXEC_STATE = 107,
     SW_FAULT_ID_PRE_GEND_WET_SELF_TEST_INVALID_EXEC_STATE1 = 108,
     SW_FAULT_ID_UF_INVALID_EXEC_STATE = 109,
+    SW_FAULT_ID_SPENT_CHAMBER_FILL_INVALID_EXEC_STATE = 110,
 #ifdef __PUMPTEST__
     // Assigning high value to separate from actual fault id from test fault ids.
     SW_FAULT_ID_PISTON_PUMP_EXEC_INVALID_STATE = 9000,