2.3.1. Exception states

Each exception is in one of the following states:


The exception is not active and not pending.


The exception is waiting to be serviced by the processor.

An interrupt request from a peripheral or from software can change the state of the corresponding interrupt to pending.


An exception that is being serviced by the processor but has not completed.


An exception handler can interrupt the execution of another exception handler. In this case both exceptions are in the active state.

Active and pending

The exception is being serviced by the processor and there is a pending exception from the same source.

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