Matthew Ballinger wrote:
>     Or a much more efficient routine 
Yes less instructions, but I have hard to see if it can beat an "addwf PCL" in decode speed, once the input bits are retrieved, and we also have to store them for next time.
But I will try your suggestion too.

>would be (in parallax mnemonics):
>ChkEncoder  mov new,encoder ;move the ra port the new var
>                 and     new,#00000011   ;clear all but encoder bits
>                 mov temp, new
>                 xor     temp,old        ;is old and new same?
>                 jz      :Return         ;if so quit
>                 clc                     ;clear carry
>                 rl      old             ;shift old to align old.0 with new.1 
>bit
>                 xor     old,new         ;xor bits to determine direction
>                 jb      old.1,:up       ;if bit is 1 then up (CW,etc), if bit 
>is 0 then down (ccw,etc)

And then wee need to rotate the other way to align the other bits and xor them to see if it was up.
And if neither up or dn, and not same, both bits changed = overspeed or error.

Did I get it right?

/Morgan


Morgans Reglerteknik, HŠllekŒs, 277 35 KIVIK, SWEDEN
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