Index: firmware/App/Controllers/Heaters.h
===================================================================
diff -u -r54f45c387430e440ab4607451fc84dea61f273f1 -r853d846a60d61d1c6f8987d9cdcfc2bc32913840
--- firmware/App/Controllers/Heaters.h	(.../Heaters.h)	(revision 54f45c387430e440ab4607451fc84dea61f273f1)
+++ firmware/App/Controllers/Heaters.h	(.../Heaters.h)	(revision 853d846a60d61d1c6f8987d9cdcfc2bc32913840)
@@ -28,6 +28,24 @@
  *  @{
  */
 
+#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;
+
+#pragma pack(pop)
+
 void initHeaters( void );
 
 void setPrimaryHeaterTargetTemperature( F32 targetTemp );
@@ -39,6 +57,8 @@
 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 );