Index: firmware/App/Modes/ModeRecirculate.c
===================================================================
diff -u -r138efd92a8645e0d2fe422409ef5a33dd2929a25 -rc48a99d2d1c852adcc986253b6c420a90dab7bfe
--- firmware/App/Modes/ModeRecirculate.c	(.../ModeRecirculate.c)	(revision 138efd92a8645e0d2fe422409ef5a33dd2929a25)
+++ firmware/App/Modes/ModeRecirculate.c	(.../ModeRecirculate.c)	(revision c48a99d2d1c852adcc986253b6c420a90dab7bfe)
@@ -14,7 +14,10 @@
  *
  **************************************************************************/
 
+#include "FPGA.h"
 #include "OperationModes.h"
+#include "ROPump.h"
+#include "TaskGeneral.h"
 #include "Timers.h"
 #include "ModeRecirculate.h"
 
@@ -29,27 +32,23 @@
 
 // ********** private definitions **********
 
-/// Enumberation of re-circulation mode states.
-typedef enum Recirculate_Mode_States
-{
-    RECIRCULATE_MODE_STATE_START = 0,                          ///< Start re-circulation mode state.
-    RECIRCULATE_MODE_STATE_CHECK_INLET_WATER,                  ///< Check inlet water state.
-    RECIRCULATE_MODE_STATE_RECIRC_PRODUCT_WATER,               ///< Re-circulate product water state.
-    NUM_OF_RECIRCULATE_MODE_STATES                             ///< Number of fill mode states.
-} RECIRCULATE_MODE_STATE_T;
+#define TARGET_RO_PRESSURE_PSI          120                    ///< Target pressure for RO pump.
+#define FLUSH_LINES_VOLUME_ML           100.0                  ///< Water volume to flush when starting re-circulate mode.
 
 // ********** private data **********
 
 static RECIRCULATE_MODE_STATE_T recircState;                   ///< Currently active re-circulation state.
+static F32 flushLinesVolume = 0.0;                             ///< Volume of water pumped by RO pump during flush lines state.
 
 // ********** private function prototypes **********
 
-static RECIRCULATE_MODE_STATE_T handleCheckInletWaterState( void );
-static RECIRCULATE_MODE_STATE_T handleRecircProductWaterState( void );
+static RECIRCULATE_MODE_STATE_T handleFlushLinesState( void );
+static RECIRCULATE_MODE_STATE_T handleRecircWaterState( void );
+static RECIRCULATE_MODE_STATE_T handleRecircPauseState( void );
 
 /*********************************************************************//**
- * @brief initFillMode
- * The initFillMode function initializes the Fill Mode module.
+ * @brief
+ * The initRecirculateMode function initializes the Fill Mode module.
  * @details
  * Inputs : none
  * Outputs : Fill Mode module initialized.
@@ -58,47 +57,60 @@
 void initRecirculateMode( void )
 {
     recircState = RECIRCULATE_MODE_STATE_START;
+    flushLinesVolume = 0.0;
 }
 
 /*********************************************************************//**
- * @brief transitionToFillMode
- * The transitionToFillMode function prepares for transition to \n
+ * @brief
+ * The transitionToRecirculateMode function prepares for transition to \n
  * fill mode.
  * @details
  * Inputs : none
- * Outputs : fillState
+ * Outputs : recircState
  * @return none
  *************************************************************************/
 void transitionToRecirculateMode( void )
 {
-    recircState = RECIRCULATE_MODE_STATE_START;
+    // re-initialize each time we transition to re-circulate mode
+    initRecirculateMode();
+
+    // TODO - set initial actuator states
+    setFPGAValveStates(0x014F);
+    // VPi open, VRc re-circ, VDr and VPo to drain
+    // UV on
+    // Primary heater on
 }
 
 /*********************************************************************//**
- * @brief execFillMode
- * The execFillMode function executes the Fill Mode state machine.
+ * @brief
+ * The execRecirculateMode function executes the Re-circulate Mode state machine.
  * @details
- * Inputs : fillState
- * Outputs : fillState
+ * Inputs : recircState
+ * Outputs : recircState
  * @return none
  *************************************************************************/
 void execRecirculateMode( void )
 {
-    // execute current Fill state
+    // execute current re-circulate state
     switch ( recircState )
     {
         case RECIRCULATE_MODE_STATE_START:
-            recircState = RECIRCULATE_MODE_STATE_CHECK_INLET_WATER;
+            setROPumpTargetPressure( TARGET_RO_PRESSURE_PSI, PUMP_CONTROL_MODE_CLOSED_LOOP );
+            recircState = RECIRCULATE_MODE_STATE_FLUSH_LINES;
             break;
 
-        case RECIRCULATE_MODE_STATE_CHECK_INLET_WATER:
-            recircState = handleCheckInletWaterState();
+        case RECIRCULATE_MODE_STATE_FLUSH_LINES:
+            recircState = handleFlushLinesState();
             break;
 
-        case RECIRCULATE_MODE_STATE_RECIRC_PRODUCT_WATER:
-            recircState = handleRecircProductWaterState();
+        case RECIRCULATE_MODE_STATE_RECIRC_WATER:
+            recircState = handleRecircWaterState();
             break;
 
+        case RECIRCULATE_MODE_STATE_PAUSE:
+            recircState = handleRecircPauseState();
+            break;
+
         default:
             SET_ALARM_WITH_2_U32_DATA( ALARM_ID_SOFTWARE_FAULT, 0, recircState )     // TODO - add s/w fault enum to 1st data param
             recircState = RECIRCULATE_MODE_STATE_START;
@@ -108,36 +120,92 @@
 
 /*********************************************************************//**
  * @brief
- * The handleCheckInletWaterState function executes the Check Inlet Water \n
- * state of the Fill Mode state machine.
+ * The handleCheckInletWaterState function executes the flush lines \n
+ * state of the Re-circulate Mode state machine.
  * @details
  * Inputs : none
  * Outputs :
- * @param none
  * @return the next state
  *************************************************************************/
-static RECIRCULATE_MODE_STATE_T handleCheckInletWaterState( void )
+static RECIRCULATE_MODE_STATE_T handleFlushLinesState( void )
 {
-    RECIRCULATE_MODE_STATE_T result = RECIRCULATE_MODE_STATE_CHECK_INLET_WATER;
+    RECIRCULATE_MODE_STATE_T result = RECIRCULATE_MODE_STATE_FLUSH_LINES;
+    F32 waterFlowRate = getMeasuredROFlowRate();
+    F32 waterVolume = ( ( waterFlowRate / SEC_PER_MIN ) / ( MS_PER_SECOND / TASK_GENERAL_INTERVAL ) );
 
+    flushLinesVolume += waterVolume;
+
+    // when enough water volume has flowed to flush the lines, transition to re-circ state
+    if ( flushLinesVolume >= FLUSH_LINES_VOLUME_ML )
+    {
+        // TODO - change VDr from drain to re-circulate
+        result = RECIRCULATE_MODE_STATE_RECIRC_WATER;
+    }
+
     return result;
 }
 
 /*********************************************************************//**
  * @brief
- * The handleRecircProductWaterState function executes the Create Product \n
- * Water state of the Fill Mode state machine.
+ * The handleRecircProductWaterState function executes the re-circulate \n
+ * water state of the Re-circulate Mode state machine.
  * @details
  * Inputs : none
  * Outputs :
- * @param none
  * @return the next state
  *************************************************************************/
-static RECIRCULATE_MODE_STATE_T handleRecircProductWaterState( void )
+static RECIRCULATE_MODE_STATE_T handleRecircWaterState( void )
 {
-    RECIRCULATE_MODE_STATE_T result = RECIRCULATE_MODE_STATE_RECIRC_PRODUCT_WATER;
+    RECIRCULATE_MODE_STATE_T result = RECIRCULATE_MODE_STATE_RECIRC_WATER;
 
     return result;
 }
 
+/*********************************************************************//**
+ * @brief
+ * The handleRecircPauseState function executes the pause state of the \n
+ * Re-circulate Mode state machine.
+ * @details
+ * Inputs : none
+ * Outputs :
+ * @return the next state
+ *************************************************************************/
+static RECIRCULATE_MODE_STATE_T handleRecircPauseState( void )
+{
+    RECIRCULATE_MODE_STATE_T result = RECIRCULATE_MODE_STATE_PAUSE;
+
+    return result;
+}
+
+/*********************************************************************//**
+ * @brief
+ * The requestDGStop function handles an HD request to stop (return to Standby mode).
+ * @details
+ * Inputs : none
+ * Outputs : DG standby mode requested
+ * @return TRUE if request accepted, FALSE if not.
+ *************************************************************************/
+BOOL requestDGStop( void )
+{
+    BOOL result = TRUE;
+
+    requestNewOperationMode( MODE_STAN );
+
+    return result;
+}
+
+/*********************************************************************//**
+ * @brief
+ * The getRecirculateModeState function returns the current state of the \n
+ * re-circulate mode.
+ * @details
+ * Inputs : recircState
+ * Outputs : none
+ * @return the current state of re-circulate mode.
+ *************************************************************************/
+RECIRCULATE_MODE_STATE_T getRecirculateModeState( void )
+{
+    return recircState;
+}
+
 /**@}*/