Sean Breheny wrote:
> Does your encoder have explicit detents? If so, I think that each
> detent is usually one count, not 4.

Hmm.  The ones I have seen have been one full quadrature cycle per detent.
That means 4 state transitions per detent, but one "count" or "position" as
described in the datasheet.

There is good reason for this scheme, so I'm a little surprised you really
found a encoder with one detent per individual state.   The reason is that
the length of each state is going to vary from the ideal of 1/4 cycle.  You
can get some additional position information from the state, but the
accuracy is usually not guaranteed.  So the states within a cycle may be a
bit irregular, but since whole cycles repeat, those can be counted on to the
accuracy stated in the datasheet.

Another way to think about this is that a quadrature encoder is intended for
measuring position in whole cycles, which is where the detents are for those
that have detents.  The 4 states/cycle are only to provide the signals to
robustly decode whole cycles while tolerating irregularity and bouncing
between adjacent states.


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