/* Registers a callback. 
Registers the user callback and enables the interrupt */
void aon_sleep_timer_register_callback(aon_sleep_timer_callback_t fun)
/* Registers a callback. 
Registers the user callback and enables the interrupt */
void aon_sleep_timer_register_callback(aon_sleep_timer_callback_t fun)
{
	aon_sleep_timer_callback = fun;
	NVIC_EnableIRQ(AON_SLEEP_TIMER0_IRQn);
}