void LPCInitVIC()
{
volatile unsigned long * pVecAdd, *pVecCntl;
int i;
// Assign all interrupt channels to IRQ
VICINTSELECT = 0;
// Disable all interrupts
VICINTENCLEAR = 0xFFFFFFFF;
// Clear all software interrupts
VICSOFTINTCLEAR = 0xFFFFFFFF;
// VIC registers can be accessed in User or privileged mode
VICPROTECTION = 0;
// Clear interrupt
VICADDRESS = 0;

// Clear address of the Interrupt Service routine (ISR) for vectored IRQs
// and disable all vectored IRQ slots
for(i = 0, pVecCntl = &VICVECTPRIORITY0, pVecAdd = &VICVECTADDR0; i < 32; ++i)
{
*pVecCntl++ = *pVecAdd++ = 0;
}
}


Вот стандартный вид обработчика
__irq __arm void irq_handler(void)
{
void (*interrupt_function)();
unsigned int vector;

vector = VICADDRESS; // Get interrupt vector.
interrupt_function = (void(*)())vector;
if( interrupt_function != (void(*)())0 )
{
interrupt_function(); // Call vectored interrupt function.
VICADDRESS = 0; // Clear interrupt in VIC.
}

}

Вместо interrupt_function(); вызывай свой _blink();