CLOCK register is now only accessed once in getEpoch()

This reduces the number of synchronised accesses to the
CLOCK register. Also it ensures that the values haven't changed
in the middle of the epoch calculation.

Author: GabrielNotman

src/RTCZero.cpp

@@ -303,17 +303,21 @@ void RTCZero::setAlarmDate(uint8_t day, uint8_t month, uint8_t year)
 
 uint32_t RTCZero::getEpoch()
 {
+  RTCreadRequest();
+  RTC_MODE2_CLOCK_Type clockTime;
+  clockTime.reg = RTC->MODE2.CLOCK.reg;
+
   struct tm tm;
 
   tm.tm_isdst = -1;
   tm.tm_yday = 0;
   tm.tm_wday = 0;
-  tm.tm_year = getYear() + EPOCH_TIME_YEAR_OFF;
-  tm.tm_mon = getMonth() - 1;
-  tm.tm_mday = getDay();
-  tm.tm_hour = getHours();
-  tm.tm_min = getMinutes();
-  tm.tm_sec = getSeconds();
+  tm.tm_year = clockTime.bit.YEAR + EPOCH_TIME_YEAR_OFF;
+  tm.tm_mon = clockTime.bit.MONTH - 1;
+  tm.tm_mday = clockTime.bit.DAY;
+  tm.tm_hour = clockTime.bit.HOUR;
+  tm.tm_min = clockTime.bit.MINUTE;
+  tm.tm_sec = clockTime.bit.SECOND;
 
   return mktime(&tm);
 }
@@ -365,7 +369,7 @@ void RTCZero::config32kOSC()
 
 /* Synchronise the CLOCK register for reading*/
 inline void RTCZero::RTCreadRequest() {
-  RTC->MODE2.READREQ.reg |= RTC_READREQ_RREQ;
+  RTC->MODE2.READREQ.reg = RTC_READREQ_RREQ | RTC_READREQ_ADDR(0x10);
   while (RTCisSyncing())
     ;
 }