Index: firmware/App/Controllers/Heaters.h
===================================================================
diff -u -r54f45c387430e440ab4607451fc84dea61f273f1 -r5c967dc311b485769e50e5e4f122be21079b5ae9
--- firmware/App/Controllers/Heaters.h	(.../Heaters.h)	(revision 54f45c387430e440ab4607451fc84dea61f273f1)
+++ firmware/App/Controllers/Heaters.h	(.../Heaters.h)	(revision 5c967dc311b485769e50e5e4f122be21079b5ae9)
@@ -23,11 +23,45 @@
 /**
  *  @defgroup Heaters Heaters
  *  @brief Heaters driver modules. Controls the primary and trimmer heaters.
+ *  The primary heaters are manufactured by Heatron, PN: UEL14EXK2A-Rev D with
+ *  fluid operating temperature in between 5 degrees C and 95 degrees C.
+ *  The trimmer heater is manufactured by Heatron, PN: UEL5EXK1A-Rev D with
+ *  fluid operating temperature in between 5 degrees C and 95 degrees C.
  *
  *  @addtogroup Heaters
  *  @{
  */
 
+// ********** Public definitions **********
+
+#pragma pack(push,1)
+
+/// Target temperature data structure.
+typedef struct
+{
+    F32 targetPrimaryHeaterTemp;    ///< Primary heater set temperature target
+    F32 targetTrimmerHeaterTemp;    ///< Trimmer heater set temperature target
+} TARGET_TEMPS_PAYLOAD_T;
+
+/// Trimmer heater command data structure.
+typedef struct
+{
+    BOOL startHeater;      ///< Flag indicates start or stop heater
+    F32 targetTemp;        ///< Target temperature for heater
+} TRIMMER_HEATER_CMD_T;
+
+/// Heaters data struct.
+typedef struct
+{
+    F32 mainPrimayHeaterDC;                 ///< Main primary heater DC
+    F32 smallPrimaryHeaterDC;               ///< Small primary heater DC
+    F32 trimmerHeaterDC;                    ///< Trimmer heater DC
+} HEATERS_DATA_T;
+
+#pragma pack(pop)
+
+// ********** Public function prototypes **********
+
 void initHeaters( void );
 
 void setPrimaryHeaterTargetTemperature( F32 targetTemp );
@@ -39,6 +73,8 @@
 void stopPrimaryHeater( void );
 void stopTrimmerHeater( void );
 
+void handleTrimmerHeaterCmd( TRIMMER_HEATER_CMD_T *heaterCmdPtr ); // handle trimmer heater control command from HD
+
 void execHeatersMonitor( void );
 
 SELF_TEST_STATUS_T execHeatersSelfTest( void );