I have written some code to generate an interrupt from the RTC alarm. This includes sub seconds. This works well for times in excess of 1 second. The alarm time, including subseconds is calculated and displayed. When the interrupt is hit the time is read again and the difference is only a few subsecond counts. However when a short time (less than 1 second) is tried it will fail if the only thing that changes are the subseconds. Then the interrupt is not triggered. This does not seem expected behaviour, any workarounds out there?