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Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
16 years ago

Code blocked in the ISR routine...

Hi,

I want to generate a simple Push Button ISR routine...

But my code didn't work...

The interrupt occurs but the program still in the ISR routine...

Here the declaration of the init_button_pio() 

    static void init_button_pio()
    {
        /* Recast the edge_capture pointer to match the
        alt_irq_register() function prototype. */
        void* edge_capture_ptr = (void*) &edge_capture;
        /* Disable button interrupts. */
        IOWR_ALTERA_AVALON_PIO_IRQ_MASK(button_BASE, 0x0);
        /* Reset the edge capture register. */
        IOWR_ALTERA_AVALON_PIO_EDGE_CAP(button_BASE, 0x1);
        
        /* Register the ISR. */
        alt_irq_register( button_IRQ, edge_capture_ptr, handle_button_interrupts );
       
        /* Enable button interrupts. */
        IOWR_ALTERA_AVALON_PIO_IRQ_MASK(button_BASE, 0x1);
    }

And, here the ISR routine : 

    static void handle_button_interrupts(void* context, alt_u32 id)
    {
        /* cast the context pointer to an integer pointer. */
        volatile int* edge_capture_ptr = (volatile int*) context;
        /*
        * Read the edge capture register on the button PIO.
        * Store value.
        */
        *edge_capture_ptr = IORD_ALTERA_AVALON_PIO_EDGE_CAP(button_BASE);
        
        /* Write to the edge capture register to reset it. */
        IOWR_ALTERA_AVALON_PIO_EDGE_CAP(button_BASE, 0x0);
        /* MY CODE*/
        IOWR_ALTERA_AVALON_PIO_DATA(leds_BASE, ledCount ++);
        
         
        /* reset interrupt capability for the Button PIO. */
        IOWR_ALTERA_AVALON_PIO_IRQ_MASK(button_BASE, 0x1);
    }

I don't understand why my code is staying in the ISR, I reset the edge capture register...

Thank you for your help.

1 Reply

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    16 years ago

    Hi there,

    Is your button input de-bounced? If not it could generate a series of consecutive interrupt requests so that as soon as you leave the ISR it re-enters again. If you run your code, rather than step through it, what happens? I'd guess that it would change the state of your LEDs, but in a somewhat erratic fashion.

    If your button inputs are debounced to provide a single clean edge, there should be no problem.

    Cheers