Index: firmware/App/Controllers/Heaters.h
===================================================================
diff -u -re0265b8fad80add7a5d54db11ecc72fd6b1665a8 -r9ce06772b2f651c57144327e6cbf886e2bc22dee
--- firmware/App/Controllers/Heaters.h	(.../Heaters.h)	(revision e0265b8fad80add7a5d54db11ecc72fd6b1665a8)
+++ firmware/App/Controllers/Heaters.h	(.../Heaters.h)	(revision 9ce06772b2f651c57144327e6cbf886e2bc22dee)
@@ -32,17 +32,31 @@
  *  @{
  */
 
-// ********** public definitions **********
+#pragma pack(push,1)
 
-/// Heaters data publish struct
+/// Target temperature data structure.
 typedef struct
 {
-    F32 mainPrimaryDutyCyclePct;      ///< Main primary heater duty cycle in percent.
-    F32 smallPrimaryDutyCyclePct;     ///< Small primary heater duty cycle in percent.
-    F32 trimmerDutyCyclePct;          ///< Trimmer heater duty cycle in percent.
+    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
+{
+    U32 mainPrimayHeaterDC;                 ///< Main primary heater DC
+    U32 smallPrimaryHeaterDC;               ///< Small primary heater DC
+    U32 trimmerHeaterDC;                    ///< Trimmer heater DC
 } HEATERS_DATA_T;
 
-// ********** public function prototypes **********
+#pragma pack(pop)
 
 void initHeaters( void );
 
@@ -55,6 +69,8 @@
 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 );