Current scheme involves trying to fence the current count by knowing the direction with CMP to trigger at the next position. Direction-change interrupts to alter which side CMP is placed with ARR match to handle the starting case where we don't really know the direction.
However, that is a bigger mess than seems reasonable because the desire to be notified whenever the count changes is just about the first thing people would want to do and should have been designed in. Does anyone have a clue?
