All interrupt vectors are assigned to one of three possible priority levels, as
shown in the table below. An interrupt request from a high-priority source will interrupt
any ongoing interrupt handler from a normal-priority source. When returning from the
high-priority interrupt handler, the execution of the normal-priority interrupt handler
will resume.
Table 13-2. Interrupt Priority Levels
| Priority |
Level |
Source |
| Highest |
Non-Maskable Interrupt |
Device-dependent and statically assigned |
| ... |
Level 1 (high priority) |
One vector is optionally user selectable as level 1 |
| Lowest |
Level 0 (normal priority) |
The remaining interrupt vectors |
