In my application- counter for readout of rotary
encoders and linear scales- I have used an 89C1051
to solely do this duty of decoding quadrature signals
to pulse and direction output for 89C52-T2 up/dn
counting. The code-quad1- courtesy John Veazey needed
only a small modification to suit my application. In
the agilent chip, they have described a filter that
bars very fast transients from disturbing the count.
I want to implement that idea. The code-the entire
counter- mm/inch,rad/dia,inc/abs,8 digit display- is
available to interested hobbyists as a thanksgiving
for all the help received from sources here.I want to
thank Peter Dannegar for his keyscan routine(wondrous)
and Dr Marshal for his help with maths.