I would just poll the inputs in a fixed-time based interrupt routine. For
normal manual rotation you'd have no trouble keeping up.

Assume the two inputs are called A and B.

We have a value called and 'SaveB'

On each interrupt:

if B <> SaveB then

    if A is high then increment the controlled value
    else decrement the controlled value

    Set B to SaveB

endif

It is really that simple.

Bob Ammerman
RAm Systems

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