Index: firmware/App/Services/FpgaDD.c
===================================================================
diff -u -r322747d530c1b8205be257557e53dcfe9caad50a -r521cd469ec8e35476a27475170848d0f62aa0ec8
--- firmware/App/Services/FpgaDD.c	(.../FpgaDD.c)	(revision 322747d530c1b8205be257557e53dcfe9caad50a)
+++ firmware/App/Services/FpgaDD.c	(.../FpgaDD.c)	(revision 521cd469ec8e35476a27475170848d0f62aa0ec8)
@@ -90,7 +90,8 @@
 
 #define FPGA_D6_FLOATER_LEVEL_BIT       0x03                    ///< Floater level bit mask.
 
-#define FPGA_D5_HEATER_CNTRL_BIT   0x01                         ///< FPGA GIO D5 heater control bit mask
+#define FPGA_D5_HEATER_CNTRL_BIT        0x01                    ///< FPGA GIO D5 heater control bit mask
+#define FPGA_D5_HEATER_PWM_ENABLE_BIT   0x02                    ///< FPGA D5 PWM based heater control bit mask
 
 /// FPGA size of V3 read bytes.
 #define FPGA_SIZE_OF_V3_READ_BYTES      ( FPGA_READ_V3_END_BYTE_NUM - FPGA_READ_V3_START_BYTE_NUM )
@@ -324,6 +325,8 @@
     U16 fpgaD10PumpRevCount;                ///< Reg 144. Bicarb Concentrate pump revolution count
     U08 fpgaADCControl;                     ///< Reg 146. FPGA internal ADC Control register for debugging
     U08 fpgaGPIOControl;                    ///< Reg 147. FPGA GPIO control interface
+    U16 fpgaACRelayPWMLow;                  ///< Reg 148. Length of time in 10us resoultion that PWM output stays low.
+    U16 fpgaACRelayPWMPeriod;               ///< Reg 150. PWM period for AC relay/heater.
 } FPGA_ACTUATORS_T;
 #pragma pack(pop)
 
@@ -1341,6 +1344,55 @@
 
 /*********************************************************************//**
  * @brief
+ * The setFPGAD5HeaterPWMEnableControl function sets whether the primary heater
+ * control based out of On/OFF (0) or PWM based control (1).
+ * @details \b Inputs: none
+ * @details \b Outputs: fpgaGPIOControl
+ * @param enable PWM based heater control when true, otherwise On/Off Control.
+ * @return none
+ *************************************************************************/
+void setFPGAD5HeaterPWMEnableControl( BOOL enable )
+{
+    if ( TRUE == enable)
+    {
+        fpgaActuatorSetPoints.fpgaGPIOControl |= FPGA_D5_HEATER_PWM_ENABLE_BIT;
+    }
+    else
+    {
+        fpgaActuatorSetPoints.fpgaGPIOControl &= ~FPGA_D5_HEATER_PWM_ENABLE_BIT;
+    }
+}
+
+/*********************************************************************//**
+ * @brief
+ * The setFPGAD5HeaterPWMLowState function sets the PWM low period( Off time)
+ * for AC heater.
+ * @details \b Inputs: none
+ * @details \b Outputs: fpgaACRelayPWMLow
+ * @param count the number of count that PWM stays low for the AC relay/heater.
+ * @return none
+ *************************************************************************/
+void setFPGAD5HeaterPWMLowState( U16 count )
+{
+    fpgaActuatorSetPoints.fpgaACRelayPWMLow = count;
+}
+
+/*********************************************************************//**
+ * @brief
+ * The setFPGAD5HeaterPWMPeriod function sets the PWM period( On and Off time)
+ * for AC heater.
+ * @details \b Inputs: none
+ * @details \b Outputs: fpgaACRelayPWMPeriod
+ * @param period the total period of PWM cycle ( On and Off time).
+ * @return none
+ *************************************************************************/
+void setFPGAD5HeaterPWMPeriod( U16 period )
+{
+    fpgaActuatorSetPoints.fpgaACRelayPWMPeriod = period;
+}
+
+/*********************************************************************//**
+ * @brief
  * The getFPGAVersions function gets the FPGA version numbers.
  * @details \b Inputs: fpgaHeader
  * @details \b Outputs: none