Datasheet

181
SAM3X / SAM3A [DATASHEET]
Atmel-11057C-ATARM-SAM3X-SAM3A-Datasheet_23-Mar-15
• MONITORACT
Debug monitor active bit, reads as 1 if Debug monitor is active
• SVCALLACT
SVC call active bit, reads as 1 if SVC call is active
• USGFAULTACT
Usage fault exception active bit, reads as 1 if exception is active
• BUSFAULTACT
Bus fault exception active bit, reads as 1 if exception is active
• MEMFAULTACT
Memory management fault exception active bit, reads as 1 if exception is active
If you disable a system handler and the corresponding fault occurs, the processor treats the fault as a hard fault.
You 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.
• Software that changes the value of an active bit in this register without correct adjustment to the stacked content can
cause the processor to generate a fault exception. Ensure software that writes to this register retains and subsequently
restores the current active status.
•A
f
ter you have enabled the system handlers, if you have to change the value of a bit in this register you must use a
read-modify-write procedure to ensure that you change only the required bit.