Datasheet

SAM9G45 [DATASHEET]
Atmel-6438O-ATARM-SAM9G45-Datasheet_08-Dec-15
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The fast interrupt mode has seven private registers r8 to r14 (banked registers) to reduce or remove the
requirement for register saving which minimizes the overhead of context switching.
The Prefetch Abort is one of the aborts that indicates that the current memory access cannot be completed. When
a Prefetch Abort occurs, the ARM9EJ-S marks the prefetched instruction as invalid, but does not take the
exception until the instruction reaches the Execute stage in the pipeline. If the instruction is not executed, for
example because a branch occurs while it is in the pipeline, the abort does not take place.
The breakpoint (BKPT) instruction is a new feature of ARM9EJ-S that is destined to solve the problem of the
Prefetch Abort. A breakpoint instruction operates as though the instruction caused a Prefetch Abort.
A breakpoint instruction does not cause the ARM9EJ-S to take the Prefetch Abort exception until the instruction
reaches the Execute stage of the pipeline. If the instruction is not executed, for example because a branch occurs
while it is in the pipeline, the breakpoint does not take place.