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SAM4S [DATASHEET]

11100E–ATARM–24-Jul-13

1: The exception is pending.

Note:

The user can write to these bits to change the pending status of the exceptions.

Read:

0:  The exception is not pending.

1: The exception is pending.

Note:

The user can write to these bits to change the pending status of the exceptions.

Read:

0:  The exception is not active.

1: The exception is active.

Note:

The user can write to these bits to change the active status of the exceptions.
- Caution: A software that changes the value of an active bit in this register without a correct adjustment to the 
stacked content can cause the processor to generate a fault exception. Ensure that the software writing to this regis-
ter retains and subsequently restores the current active status.
- Caution: After enabling the system handlers, to change the value of a bit in this register, the user must use a read-
modify-write procedure to ensure that only the required bit is changed.

0:  The exception is not active.

1: The exception is active.

0: Debug monitor is not active.

1: Debug monitor is active.

0: SVC call is not active.

1: SVC call is active.

0: Usage fault exception is not active.

1: Usage fault exception is active.

0: Bus fault exception is not active.

1: Bus fault exception is active.

0: Memory management fault exception is not active.

1: Memory management fault exception is active.

If the user disables a system handler and the corresponding fault occurs, the processor treats the fault as a hard fault.

The user can write to this register to change the pending or active status of system exceptions. An OS kernel can write to the 
active bits to perform a context switch that changes the current exception type.