Try to add this line in your setup() function :
LowPower.attachInterruptWakeup(RTC_ALARM_WAKEUP, alarmEvent0, CHANGE);
And create a dummy function :
void alarmEvent0() {
alarm_source = 0;
}
Try to add this line in your setup() function :
LowPower.attachInterruptWakeup(RTC_ALARM_WAKEUP, alarmEvent0, CHANGE);
And create a dummy function :
void alarmEvent0() {
alarm_source = 0;
}