Normal-Priority Interrupts

All interrupt vectors other than NMI are assigned to priority level 0 (normal) by default. The user may override this by assigning one of these vectors as a high-priority vector. The device will have many normal-priority vectors, and some of these may be pending at the same time. Two different scheduling schemes are available to choose which of the pending normal-priority interrupts to service first: Static or round robin.

IVEC is the interrupt vector mapping, as listed in the Peripherals and Architecture section. The following sections use IVEC to explain the scheduling schemes. IVEC0 is the Reset vector, IVEC1 is the NMI vector, and so on. In a vector table with n+1 elements, the vector with the highest vector number is denoted IVECn. Reset, non-maskable interrupts, and high-level interrupts are included in the IVEC map, but will always be prioritized over the normal-priority interrupts.