At 08:41 PM 3/3/97 -0800, you wrote:

I did an encoder thingy by polling at high speed, keeping the previous value
read in in RAM, then XORing to find the deltas (a delta appears as a 1 bit).

You just need to poll fast enough to catch all the changes at the speed you
expect to move.

Kinda like below:

OldEnc  ds      1               ; Holds previous value read from encoder
NewEnc  ds      1               ; Holds current value
Deltas  ds      1               ; Holds deltas
EncPort equ     RB

ChkEnc  movf    EncPort,W
        movwf   NewEnc
        xorwf   OldEnc,W
        movwf   Deltas          ; A "1" signifies a changed bit
        btfsc   Z
        goto    ChkEnc          ; No changes, so loop, or go back to main
program
DoChg   ...                     ; Process each bit change manually


Andy




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Andy Kunz - Montana Design - 409 S 6th St - Phillipsburg, NJ 08865
          Hardware & Software for Industry & R/C Hobbies
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