using keypad input for rotary encoder

[pheist]

I'm trying to hook up a rotary encoder to my VK202-25's keypad input. (A rotary encoder is similar to what's used in a mouse wheel, for those who don't know. Perfect for selection when mounted like a radio knob.) The trouble is how to get the signal that these things generate to be useful when plugged into the keypad input. It should end up that one "click" to the right generates one character and one click to the left generates another.

These encoders produce two digital channels in quadrature, so they call it, where a leading edge on channel A before channel B means a counter-clockwise click, and a leading edge on channel B before channel A means a clockwise click. An example is in a pdf at DigiKey (http://dkc3.digikey.com/PDF/T032/0882.pdf). I think somehow I need to detect which channel's leading edge is first, then use this to close a switch for some time (through a 10k resistor of course) that connects one of the row and column lines, simulating a keypad press.

Anyone tried to do this or have any thoughts? I'll post a circuit diagram with a bill of materials somewhere if this ever ends up working out...

thanks...

Pete

[linear]

We've had a bit of discussion previosly, check this post out: http://www.lcdforums.com/forums/viewtop ... coder#6920

The link in that post is a great one. At least if you're using a microcontroller...