1) Out of 96 possible interrupts, some interrupts are not used. These interrupts are reserved for future devices. These interrupts can be
used as software interrupts if they are enabled at the PIEIFRx level, provided none of the interrupts within the group is being used by a
peripheral. Otherwise, interrupts coming in from peripherals may be lost by accidentally clearing their flag while modifying the PIEIFR.
To summarize, there are two safe cases when the reserved interrupts could be used as software interrupts:
• No peripheral within the group is asserting interrupts.
• No peripheral interrupts are assigned to the group (for example, PIE groups 5, 7, or 11) .