Index: firmware/App/Modes/ModeChemicalDisinfect.c
===================================================================
diff -u -r138efd92a8645e0d2fe422409ef5a33dd2929a25 -rc48a99d2d1c852adcc986253b6c420a90dab7bfe
--- firmware/App/Modes/ModeChemicalDisinfect.c	(.../ModeChemicalDisinfect.c)	(revision 138efd92a8645e0d2fe422409ef5a33dd2929a25)
+++ firmware/App/Modes/ModeChemicalDisinfect.c	(.../ModeChemicalDisinfect.c)	(revision c48a99d2d1c852adcc986253b6c420a90dab7bfe)
@@ -1,4 +1,4 @@
-/**************************************************************************
+/**********************************************************************//**
  *
  *  Copyright (c) 2019-2020 Diality Inc. - All Rights Reserved.
  *
@@ -17,48 +17,74 @@
 #include "ModeChemicalDisinfect.h"
 #include "OperationModes.h"
 
+/**
+ *  @addtogroup ChemicalDisinfectMode
+ *  @{
+ */
+
+// ********** private definitions **********
+
+/// Enumeration of chem. disinfect mode states.
+typedef enum Chem_States
+{
+    CHEM_DISINFECT_STATE_START = 0,                                            ///< Start chemical disinfect mode state.
+    NUM_OF_CHEM_DISINFECT_STATES                                               ///< Number of chemical disinfect mode states.
+} CHEM_DISINFECT_STATE_T;
+
 // ********** private data **********
 
+static CHEM_DISINFECT_STATE_T chemState = CHEM_DISINFECT_STATE_START;          ///< Currently active chemical disinfect state.
+
 // ********** private function prototypes **********
 
-/*************************************************************************
+/*********************************************************************//**
  * @brief
  * The initChemicalDisinfectMode function initializes the chemical disinfect Mode module.
  * @details
  * Inputs : none
  * Outputs : Module initialized.
- * @param none
  * @return none
  *************************************************************************/
 void initChemicalDisinfectMode( void )
 {
+    chemState = CHEM_DISINFECT_STATE_START;
 }
 
-/*************************************************************************
+/*********************************************************************//**
  * @brief
  * The transitionToChemicalDisinfectMode function prepares for transition to \n
  * chemical disinfect mode.
  * @details
  * Inputs : none
  * Outputs : none
- * @param none
  * @return none
  *************************************************************************/
 void transitionToChemicalDisinfectMode( void )
 {
+    initChemicalDisinfectMode();
 }
 
-/*************************************************************************
+/*********************************************************************//**
  * @brief
  * The execChemicalDisinfectMode function executes the chemical disinfect Mode state machine.
  * @details
  * Inputs : none
  * Outputs : none
- * @param none
  * @return none
  *************************************************************************/
 void execChemicalDisinfectMode( void )
 {
+    // execute current chemical disinfect state
+    switch ( chemState )
+    {
+        case CHEM_DISINFECT_STATE_START:
+            break;
 
+        default:
+            chemState = CHEM_DISINFECT_STATE_START;
+            // TODO - s/w fault
+            break;
+    }
 }
 
+/**@}*/