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Arm LPC2138 Timer Vic Problem with Disable

Brian Hayes

I have a problem with Timers and the VIC on an Arm LPC2138.
I have two timers that run fine, both are programmed thru the VIC and are IRQ. In the main program loop, I need to disable one of the Interrupts (Timer0) in order to reset a variable that is updated in the timer Interrupt.
When I disable timer0 in the VIC, the program runs but the interrupts don't fire.
ie: Case (1)

unsigned char hw_msec(void)
        {
        static unsigned char milli_count = 0;
        VICIntEnClr |= (1 << 4); // Disable Time 0 in Vic
        milli_count = uiGlobalTimerMs;
        if(milli_count)
        {
        uiGlobalTimerMs = 0;
        }
        VICIntEnable |= (1 << 4); // Re-Enable Timner 0
        return milli_count;
        }


However it works when I disable all IRQs, but I would prefer not to have to do that: Case (2)

unsigned char hw_msec(void)
        {
        static unsigned char milli_count = 0;
        milli_count = uiGlobalTimerMs;
        if(milli_count)
                {
                hw_irq_disable();
                uiGlobalTimerMs = 0;
                hw_irq_enable();
                }
        return milli_count;
        }


I have stopped the program in Case (1) at Line: VICIntEnClr |= (1 << 4); and the VICIntEnable is correct (0x00000030) (Timer 1 is also enabled). After stepping over VICIntEnClr, it correctly goes to (0x00000020) and after re-enabling it returns to (0x00000030). The VICVectAddr4 & 5 are both valid and the Timers are enabled (T1TCR = 1) Any Ideas would be greatly appriciated.

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