Index: firmware/App/Services/Timers.c
===================================================================
diff -u -reff7b1575f008f81b29ef906f6346fac6012d3ab -r1156c9be51ef9f40054860355ebee40b49ef03ca
--- firmware/App/Services/Timers.c	(.../Timers.c)	(revision eff7b1575f008f81b29ef906f6346fac6012d3ab)
+++ firmware/App/Services/Timers.c	(.../Timers.c)	(revision 1156c9be51ef9f40054860355ebee40b49ef03ca)
@@ -101,3 +101,33 @@
 
     return result;
 }
+
+/*************************************************************************
+ * @brief calcTimeSince
+ * The calcTimeSince function calculates the time (in ms) from a given start \n
+ * time until now.
+ * @details
+ * Inputs : msTimerCount
+ * Outputs : none
+ * @param startMSCount : the ms count at the start of the timeout period
+ * @return ms since given start time
+ *************************************************************************/
+U32 calcTimeSince( U32 startMSCount )
+{
+    U32 result;
+    U32 currMSCount = msTimerCount;
+
+    // no wrap
+    if ( currMSCount >= startMSCount )
+    {
+        result = currMSCount - startMSCount;
+    }
+    else
+    {
+        result = ( 0xFFFFFFFF - startMSCount ) + currMSCount + 1;
+    }
+
+    return result;
+}
+
+