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Parallax Forums > Public Forums > SX Microcontrollers, SX/B Compiler and SX-Key Tool > Is it normal for interrupt initialization to trigger the ISR? RESOLVED- Thanks Mojorizing!

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CarlC
Registered Member

Date Joined Oct 2005
Total Posts : 29

Posted 1/31/2006 9:15 PM (GMT -8)

While stepping through in debug mode, I find that changing the mode register to set WKPEND causes a triggering of my ISR in my initialization segment.

mov W,#$19

I even tried initially biasing my pins high (pulled up pins not connected to ground) in case seeing a low pin right after activating interrupts was causing a problem without effect.

In normal operation, my ISR uses the state of the WKPEND register (swapped through W) to determine the cause of an interrupt. I have problems when the ISR is called outside of the normal means. I guess I could put in a work around by setting a flag in the main body so the ISR is skipped through if the main hasn't been reached yet, but I'm wondering if there's a proper way to avoid running the ISR after making interrupts available during initialization.

Post Edited (CarlC) : 2/1/2006 6:19:15 AM GMT

mojorizing
Registered Member

Date Joined Jul 2004
Total Posts : 141

Posted 1/31/2006 9:59 PM (GMT -8)

Hi Carl,
In your intialization code you need to clear the WKPEND register before you enable the wake ups following a sequence such as;

;------------------------ INITIALIZATION ROUTINE -----------------------

Initialize
        ;Edge Detection Configuration

        mov     W,#$19            ;Allow Wake-Up Pending access
        mov     M,W
        mov    !rb,#%00000000        ;Clear Wake-Up Pending (WKPND_B)

        mov    W,#$1A            ;Allow Wake-Up Edge configuration
        mov    M,W
        mov    !rb,#%11111111        ;Set port B bits 0-7 to falling edge

        mov    W,#$1B            ;Allow Wake-Up Enable configuration
        mov    M,W
        mov    !rb,#%11110000        ;Set port B bits 4-7 to normal, bits 0-3 to Wake-Up Enable

        mov    W,#$1E            ;disAllow Pull-up configuration
        mov    M,W
        mov    !rb,#%11111111        ;Port B bits 0-7 without pullups

        mov    W,#$1F            ;Allow Direction configuration
        mov    M,W
        mov    !rb,#%11111111        ;Set port B bits 0-7 to input direction

        mov    W,#$19            ;Allow Wake-Up Pending access
        mov    M,W
        mov    !rb,#%00000000        ;Clear Wake-Up Pending (WKPND_B)

does this answer your question?

Bad spellers of the world untie!

CarlC
Registered Member

Date Joined Oct 2005
Total Posts : 29

Posted 1/31/2006 10:18 PM (GMT -8)

Thanks mojo,

that was exactly my problem. I forgot to clear all the interrupt flags before enabling the interrupts.

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