>Not convinced about this.  The output would have the same
>mark/space irrespective of direction.  With no reference
>to compare this signal to, how would the direction be
>decoded?  In fact, you'd get the same output with just
>one sensor AFAICT.

Forget mark/space, think analogue voltage. As the spoke moves clockwise
(say) the spoke will shield a portion of the sensor so the voltage on the
output pin will go (say) high for a midpoint voltage. This could be enough
to put the trigger point outside the window of the chip, thereby generating
an interrupt, or whatever is used to sense the position. As the spoke keeps
moving the voltage will go towards midrail again as the spoke shields both
parts equally, and then as the other half of the sensor gets shielded the
voltage goes low, and again outside the window, generating another
interrupt.

I believe doing this with a 16F630/676/627/628 or any others with
comparators would allow you to sense the mouse mickeys quite successfully.

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