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Debounce Both States / Asm / Freescale 908 2011-06-13

I wrote this for toggle switches. It first looks for a change of state. If seen, it counts loops to be constantly in that state, any reversal reloads counter. Exit is by loop countout: consistent state change OR too many reloads. In effect, it soft delays out the bounce. The loop counts set debounce delay and excessive reload countout. My std rules: free to use, But put "uMax/Sarge" associated with it somewhere. TNX <<<)))

Code:
dbict   equ     $10             ;debounce Inactive count
dbact   equ     $20             ;debounce Active count
swtank  ds.b    1               ;btns/sws input tank
swprev  ds.b    1               ;previous sw state for debouncing

Sw_In:  psha
        mov	PTAD,swtank          ;get current Sw state
        lda     swtank
        cmp     swprev          ;current=previous: Xit
        beq     SWIXit
        mov     #dbict,dbIctr   ;load debounce Inactive counter
SwDbLL: mov     #dbact,dbActr   ;load debounce Active counter
        mov     swtank,swprev   ;put current->previous
        dbnz    dbIctr,SwDbLD   ;only load active debounce N times
        bra     SWIXit          ;Not full active == off
SwDbLD: bsr     SwRead          ;get current Sw state
        lda     swtank
        cmp     swprev          ; :: previous
        bne     SwDbLL          ;Any bounce to different state resets counter
        dbnz    dbActr,SwDbLD   ;must stay on for #dbact counter loops
SWIXit: pula
        rts
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OlPhart
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