Hello all! This is my first post to the message boards. I'm going to try and give all the info I can here in the beginning so everyone will understand my situation.

I am using a relatively high resolution optical encoder (1024 pulses per revolution) to determine position in a linear slide system. The encoder outputs the standard quadrature signal (channel A and channel B).

The fastest frequency that will come from the encoder will be approximately 4864 Hz. (Stepper motor resolution=0.9 degrees per step, max frequency to stepper motor=1.9 kHz).

I actually could have gotten away with using a 50 ppr encoder, but I am a student and this one was donated.

As this is an incremental encoder and not an absolute encoder, I need to be able to continually increment/decrement a positional value in my 89C51.

At each end of the rails on the linear slide system there will be a limit switch. This is both for a positional "reset" and safety. When my trolley travels all the way to the end and hits a limit switch, the internal count in my code needs to be loaded with either the min or max value.

Because I am relatively new to assembly coding, I obtained two chips that I thought would lessen the burden. They are an LS7083/7084 made by LSI/CSI.

The 7083 will take quadrature signals in and output separate "clock up" and "clock down" signals. The 7084 will take quadrature signals in and output a clock signal and an up/!down bit.

Main question: What is the 1) most accurate way to implement my encoder and 2) after accuracy, the easiest way to implement it?

If I have forgotten important details, please let me know. I'm not looking for someone to totally design my code for me, just some helpful tips, pointers, maybe code snippets. I've thought of using the 7084 chip, and then using the event counter on the 89C51. The problem I run into is being able to decrement and/or reading the up/down bit simultaneously.

Thanks ahead for all suggestions,

David Sanders