Preempting Low-Priority Interrupts

Low-priority interrupts can be preempted by high-priority interrupts. While in the low-priority ISR, if a high-priority interrupt arrives, the high-priority interrupt request is generated and the low-priority ISR is suspended, while the high-priority ISR is executed.

After the high-priority ISR is complete and if any other high-priority interrupt requests are not active, the execution returns to the preempted low-priority ISR.

Figure 1. Interrupt Execution: High-Priority Interrupt Preempting Low-Priority Interrupts