Atmel SAM4S-XPLD Atmel ATSAM4S-XPLD ATSAM4S-XPLD データシート

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SAM4S [DATASHEET]

11100E–ATARM–24-Jul-13

Notes: 1. Occurs on an access to an XN region even if the processor does not include an MPU or the MPU is disabled.

2. Attempt to use an instruction set other than the Thumb instruction set, or return to a non load/store-multiple instruction 

with ICI continuation.

All faults exceptions except for hard fault have configurable exception priority, see 

.

The software can disable the execution of the handlers for these faults, see 

.Usually, the exception priority, together with the values of the exception mask registers, determines whether the
processor enters the fault handler, and whether a fault handler can preempt another fault handler, as described in

.

In some situations, a fault with configurable priority is treated as a hard fault. This is called priority escalation, and the
fault is described as escalated to hard fault. Escalation to hard fault occurs when:



A fault handler causes the same kind of fault as the one it is servicing. This escalation to hard fault occurs because 
a fault handler cannot preempt itself; it must have the same priority as the current priority level.



A fault handler causes a fault with the same or lower priority as the fault it is servicing. This is because the handler 
for the new fault cannot preempt the currently executing fault handler.



An exception handler causes a fault for which the priority is the same as or lower than the currently executing 
exception.



A fault occurs and the handler for that fault is not enabled.

If a bus fault occurs during a stack push when entering a bus fault handler, the bus fault does not escalate to a hard fault.
This means that if a corrupted stack causes a fault, the fault handler executes even though the stack push for the handler
failed. The fault handler operates but the stack contents are corrupted. 

Note:

Only Reset and NMI can preempt the fixed priority hard fault. A hard fault can preempt any exception other than 
Reset, NMI, or another hard fault.

The fault status registers indicate the cause of a fault. For bus faults and memory management faults, the fault address
register indicates the address accessed by the operation that caused the fault, as shown in 

Attempt to access a coprocessor

Usage fault

NOCP

Undefined instruction

UNDEFINSTR

INVSTATE

Invalid EXC_RETURN value

INVPC

Illegal unaligned load or store

UNALIGNED

Divide By 0

DIVBYZERO

Hard fault

SCB_HFSR

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