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11100B–ATARM–31-Jul-12
SAM4S Series [Preliminary]
Memory Management Fault (MemManage)
A Memory Management Fault is an exception that occurs because of a memory protection
related fault. The MPU or the fixed memory protection constraints determines this fault, for both
instruction and data memory transactions. This fault is used to abort instruction accesses to
Execute Never (XN) memory regions, even if the MPU is disabled.
Bus Fault
A Bus Fault is an exception that occurs because of a memory related fault for an instruction or
data memory transaction. This might be from an error detected on a bus in the memory system.
Usage Fault
A Usage Fault is an exception that occurs because of a fault related to an instruction execution.
This includes:
• an undefined instruction
• an illegal unaligned access
• an invalid state on instruction execution
• an error on exception return.
The following can cause a Usage Fault when the core is configured to report them:
• an unaligned address on word and halfword memory access
• a division by zero.
SVCall
A supervisor call (SVC) is an exception that is triggered by the SVC instruction. In an OS envi-
ronment, applications can use SVC instructions to access OS kernel functions and device
drivers.
PendSV
PendSV is an interrupt-driven request for system-level service. In an OS environment, use
PendSV for context switching when no other exception is active.
SysTick
A SysTick exception is an exception the system timer generates when it reaches zero. Software
can also generate a SysTick exception. In an OS environment, the processor can use this
exception as system tick.
Interrupt (IRQ)
A interrupt, or IRQ, is an exception signalled by a peripheral, or generated by a software
request. All interrupts are asynchronous to instruction execution. In the system, peripherals use
interrupts to communicate with the processor.
Table 11-9.
Properties of the Different Exception Types
Exception
Number
Irq Number
Exception Type
Priority
Vector Address
or Offset
Activation
1
-
Reset
-3, the highest
0x00000004
Asynchronous
2
-14
NMI
-2
0x00000008
Asynchronous
3
-13
Hard fault
-1
0x0000000C
-
Summary of Contents for SAM4S Series
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