Index: firmware/App/Modes/Prime.c
===================================================================
diff -u -r3e0d27b2607ac2ec6cead5360af682e40ec6e80f -r1f91b5a53bda942b0967817bbd5e68a499dbf816
--- firmware/App/Modes/Prime.c	(.../Prime.c)	(revision 3e0d27b2607ac2ec6cead5360af682e40ec6e80f)
+++ firmware/App/Modes/Prime.c	(.../Prime.c)	(revision 1f91b5a53bda942b0967817bbd5e68a499dbf816)
@@ -1,14 +1,14 @@
 /**************************************************************************
 *
-* Copyright (c) 2020-2022 Diality Inc. - All Rights Reserved.
+* Copyright (c) 2020-2023 Diality Inc. - All Rights Reserved.
 *
 * THIS CODE MAY NOT BE COPIED OR REPRODUCED IN ANY FORM, IN PART OR IN
 * WHOLE, WITHOUT THE EXPLICIT PERMISSION OF THE COPYRIGHT OWNER.
 *
 * @file    Prime.c
 *
-* @author  (last)      Sean Nash
-* @date    (last)      02-Dec-2022
+* @author  (last)      Michael Garthwaite
+* @date    (last)      19-Jan-2023
 *
 * @author  (original)  Quang Nguyen
 * @date    (original)  08-Dec-2020
@@ -218,6 +218,8 @@
  *************************************************************************/
 void execPrime( void )
 {
+    HD_PRE_TREATMENT_PRIME_STATE_T priorSubState = currentPrimeState;
+
     // execute prime sub-mode state machine
     switch ( currentPrimeState )
     {
@@ -293,6 +295,11 @@
     // Prime flags should be handled by now
     resetPrimeFlags();
 
+    if ( priorSubState != currentPrimeState )
+    {
+        SEND_EVENT_WITH_2_U32_DATA( HD_EVENT_SUB_STATE_CHANGE, priorSubState, currentPrimeState );
+    }
+
     // Broadcast priming data
     broadcastPrimingStatus();
 }