/* Registers an interrupt handler for the SysTick interrupt. */
void SysTickIntRegister(void(*pfnHandler)(void))
/* Registers an interrupt handler for the SysTick interrupt. */
void SysTickIntRegister(void(*pfnHandler)(void))
{
    IntRegister(FAULT_SYSTICK, pfnHandler);
    HWREG(NVIC_ST_CTRL) |= NVIC_ST_CTRL_INTEN;
}