Added the ability to set the match/compare mask

Now by default the interrupt is enabled but the mask
is set to no compare.

Author: GabrielNotman

src/RTCZero.cpp

@@ -64,7 +64,8 @@ void RTCZero::begin(bool timeRep)
   NVIC_EnableIRQ(RTC_IRQn); // enable RTC interrupt 
   NVIC_SetPriority(RTC_IRQn, 0x00);
 
-  RTC->MODE2.INTENSET.reg &= ~RTC_MODE2_INTENSET_ALARM0; // disable alarm interrupt by default
+  RTC->MODE2.INTENSET.reg |= RTC_MODE2_INTENSET_ALARM0; // enable alarm interrupt
+  RTC->MODE2.Mode2Alarm[0].MASK.bit.SEL = MATCH_OFF; // default alarm match is off (disabled)
 
   while (RTCisSyncing())
     ;
@@ -78,6 +79,20 @@ void RTC_Handler(void)
   RTC->MODE2.INTFLAG.reg = RTC_MODE2_INTFLAG_ALARM0; // must clear flag at end
 }
 
+void RTCZero::enableAlarm(Alarm_Match match)
+{
+  RTC->MODE2.Mode2Alarm[0].MASK.bit.SEL = match;
+  while (RTCisSyncing())
+    ;
+}
+
+void RTCZero::disableAlarm()
+{
+  RTC->MODE2.Mode2Alarm[0].MASK.bit.SEL = 0x00;
+  while (RTCisSyncing())
+    ;
+}
+
 /*
  * Get Functions
  */

src/RTCZero.h

@@ -27,8 +27,22 @@
 class RTCZero {
 public:
 
+  enum Alarm_Match: uint8_t
+  {
+    MATCH_OFF          = 0x00,
+    MATCH_SS           = 0x01,
+    MATCH_MMSS         = 0x02,
+    MATCH_HHMMSS       = 0x03,
+    MATCH_DHHMMSS      = 0x04,
+    MATCH_MMDDHHMMSS   = 0x05,
+    MATCH_YYMMDDHHMMSS = 0x06
+  };
+
   RTCZero() {};
   void begin(bool timeRep);
+
+  void enableAlarm(Alarm_Match match);
+  void disableAlarm();
 
   /* Get Functions */