Q:
What is a nested interrupt?
belongs to collection: Embedded C interview questions and answers (2022)
Embedded C interview questions and answers (2022)
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C programming
Answer:
In a nested interrupt system, an interrupt is allowed to any time and anywhere even an ISR is being executed. But, only the highest priority ISR will be executed immediately. The second highest priority ISR will be executed after the highest one is completed.
The rules of a nested interrupt system are:
- All interrupts must be prioritized.
- After initialization, any interrupts are allowed to occur anytime and anywhere.
- If a low-priority ISR is interrupted by a high-priority interrupt, the high-priority ISR is executed.
- If a high-priority ISR is interrupted by a low-priority interrupt, the high-priority ISR continues executing.
- The same priority ISRs must be executed by time order
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