Exception priority levels in ARM Architecture - Cheat Sheet & Quick Revision

Recall & Review

beginner

What are exception priority levels in ARM architecture?

Exception priority levels determine the order in which exceptions are handled. Higher priority exceptions can interrupt lower priority ones.

beginner

Name the main types of exceptions in ARM Cortex-M processors.

The main types are: Reset, NMI (Non-Maskable Interrupt), HardFault, and other configurable interrupts with different priority levels.

intermediate

How does ARM architecture assign priority to exceptions?

ARM uses a priority number where lower numbers mean higher priority. The processor always handles the exception with the highest priority first.

intermediate

What happens if two exceptions with the same priority occur simultaneously in ARM?

The exception with the lower exception number (vector number) is handled first, ensuring a consistent order.

beginner

Why is understanding exception priority important in embedded systems?

It helps design reliable systems by ensuring critical tasks interrupt less important ones, improving responsiveness and safety.

In ARM architecture, which exception has the highest priority?

A Reset

B NMI

C HardFault

D SysTick

Reset exception has the highest priority and occurs when the system starts or resets.

What does a lower priority number mean in ARM exception handling?

A Equal priority

B Lower priority

C No priority

D Higher priority

In ARM, lower priority numbers indicate higher priority exceptions.

If two exceptions have the same priority, how does ARM decide which to handle first?

A Randomly

B By exception number (lower first)

C By time of occurrence

D By software setting

ARM handles the exception with the lower exception number first when priorities are equal.

Which exception cannot be masked or disabled in ARM Cortex-M?

A PendSV

B SysTick

C NMI

D UsageFault

NMI (Non-Maskable Interrupt) cannot be disabled or masked.

Why are exception priority levels important in real-time systems?

A To ensure critical tasks run first

B To avoid exceptions

C To save memory

D To slow down processing

Priority levels ensure that critical tasks interrupt less important ones for timely response.

Explain how ARM architecture uses exception priority levels to manage multiple interrupts.

Think about how the processor decides which interrupt to handle first.

Describe why understanding exception priority levels is crucial when designing embedded systems.

Consider the impact on system safety and performance.