HEDS5540 optical encoder

[richard]

easiest way

Flag var byte
wsave VAR BYTE    $70     SYSTEM  ; alternate save location for W 
enc_new VAR BYTE
enc_old VAR BYTE
enc_counter VAR WORD

asm    

    ;Read latest input from PORTB & put the value in _enc_new.
         MOVE?CB    1 ,_Flag
         movf    PORTB,W
         movwf  _enc_new

         ;Strip off all but the 2 MSBs in _enc_new.

         movlw    B'11000000'    ;Create bit mask (bits 7 & 6).
         andwf   _enc_new,F         ;Zero bits 5 thru 0.

         ;Determine the direction of the

[mark_s]

Richard's way is the best. Just for referece it could also be done without asm since its not time sensitive.

old_enc_counter var word
Main_Loop:   
  
if enc_counter<> old_enc_counter then 'If change update LCD
Lcdout $fe, 1                    
Lcdout Dec enc_counter     ; display counter value on LCD
old_enc_counter = enc_counter
endif
goto Main_Loop
end

[louislouis]

hmm, I try it and no change, still only the "encoder test" message on the LCD.
This line is ok MOVE?CB 1 ,_Flag what means the question mark.