Adds a simple countdown timer, available as a custom view in surface and dive mode. This can be used to time safety stops, or to prebreathe a CCR (or to boil your breakfast eggs if you are so inclined). The duration of the timer is configurable from 1 second to 9:59 minutes in the System menu. The timer is started by switching to the custom view, and remaining on it until a 10 second delay has elapsed. Once the timer has started the custom view can be changed and the timer will continue running in the background. After the timer has run out 'Finished' will be shown for 10 seconds in the timer custom view, and then automatic switching of custom views (if configured) resumes. In surface mode the dive computer will not go to sleep while the timer is running, and a mini timer will be shown when the timer custom view is not showing. (mikeller)

--- a/Common/Inc/data_central.h	Thu Aug 10 21:35:34 2023 +0200
+++ b/Common/Inc/data_central.h	Mon Aug 21 17:20:07 2023 +0200
@@ -360,6 +360,14 @@
 		CHARGER_lostConnection
 };
 
+typedef enum {
+    TIMER_STATE_OFF = 0,
+    TIMER_STATE_PRESTART,
+    TIMER_STATE_RUNNING,
+    TIMER_STATE_WAIT_FINISHED,
+    TIMER_STATE_FINISHED,
+} timerState_e;
+
 typedef struct
 {
 	SDiveSettings diveSettings;
@@ -390,6 +398,9 @@
 	uint8_t sensorErrorsRTE;
 
 	uint8_t lastKnownBatteryPercentage;
+
+    timerState_e timerState;
+    int timerStartedS;
 } 	SDiveState;
 
 
@@ -512,4 +523,6 @@
 void setCompassHeading(uint16_t heading);
 
 const SDecoinfo *getDecoInfo(void);
+
+void disableTimer(void);
 #endif // DATA_CENTRAL_H