diff --git a/src/rtc.c b/src/rtc.c
--- a/src/rtc.c
+++ b/src/rtc.c
@@ -16,7 +16,7 @@ static void Error_Handler(void)
 // Initialize RTC
 void rtc_init(void)
 {
-        __HAL_RCC_RTC_ENABLE();
+	__HAL_RCC_RTC_ENABLE();
 
     
   RTC_TimeTypeDef sTime;
@@ -25,11 +25,12 @@ void rtc_init(void)
 
   hrtc.Instance = RTC;
   hrtc.Init.HourFormat = RTC_HOURFORMAT_24;
-  hrtc.Init.AsynchPrediv = 127;
-  hrtc.Init.SynchPrediv = 255;
+  hrtc.Init.AsynchPrediv = 124;
+  hrtc.Init.SynchPrediv = 322; // if this has enough bits should be 1.0018Hz based on 40kHz LSI
   hrtc.Init.OutPut = RTC_OUTPUT_DISABLE;
   hrtc.Init.OutPutPolarity = RTC_OUTPUT_POLARITY_HIGH;
   hrtc.Init.OutPutType = RTC_OUTPUT_TYPE_OPENDRAIN;
+
   if (HAL_RTC_Init(&hrtc) != HAL_OK)
   {
     Error_Handler();
@@ -55,6 +56,7 @@ void rtc_init(void)
     Error_Handler();
   }
 
+
     /**Enable the Alarm A 
     */
   sAlarm.AlarmTime.Hours = 0x0;
@@ -63,7 +65,9 @@ void rtc_init(void)
   sAlarm.AlarmTime.SubSeconds = 0x0;
   sAlarm.AlarmTime.DayLightSaving = RTC_DAYLIGHTSAVING_NONE;
   sAlarm.AlarmTime.StoreOperation = RTC_STOREOPERATION_RESET;
-  sAlarm.AlarmMask = RTC_ALARMMASK_NONE;
+
+  // Alarm will trigger on the Xth second of every minute
+  sAlarm.AlarmMask = RTC_ALARMMASK_DATEWEEKDAY | RTC_ALARMMASK_HOURS | RTC_ALARMMASK_MINUTES;
   sAlarm.AlarmSubSecondMask = RTC_ALARMSUBSECONDMASK_ALL;
   sAlarm.AlarmDateWeekDaySel = RTC_ALARMDATEWEEKDAYSEL_DATE;
   sAlarm.AlarmDateWeekDay = 0x1;
@@ -73,4 +77,18 @@ void rtc_init(void)
     Error_Handler();
   }
 
+  HAL_NVIC_SetPriority(RTC_IRQn, 0, 0);
+  HAL_NVIC_EnableIRQ(RTC_IRQn);
 }
+
+void rtc_cal(void)
+{
+	// Do something with hrtc.Instance->CALR; // this has a plus and minus component, see refman
+}
+
+RTC_HandleTypeDef* rtc_gethandle(void)
+{
+	return &hrtc;
+}
+
+