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ATSAM4S-XPLD
203
SAM4S [DATASHEET]
11100E–ATARM–24-Jul-13
• STKERR: Bus Fault on Stacking for Exception Entry
This is part of
.
0: No stacking fault.
1: Stacking for an exception entry has caused one or more bus faults.
When the processor sets this bit to 1, the SP is still adjusted but the values in the context area on the stack might be incorrect.
The processor does not write a fault address to the SCB_BFAR register.
The processor does not write a fault address to the SCB_BFAR register.
• BFARVALID: Bus Fault Address Register (BFAR) Valid flag
This is part of
.
0: The value in SCB_BFAR is not a valid fault address.
1: SCB_BFAR holds a valid fault address.
The processor sets this bit to 1 after a bus fault where the address is known. Other faults can set this bit to 0, such as a memory
management fault occurring later.
management fault occurring later.
If a bus fault occurs and is escalated to a hard fault because of priority, the hard fault handler must set this bit to 0. This prevents
problems if returning to a stacked active bus fault handler whose SCB_BFAR value has been overwritten.
problems if returning to a stacked active bus fault handler whose SCB_BFAR value has been overwritten.
• UNDEFINSTR: Undefined Instruction Usage Fault
This is part of
0: No undefined instruction usage fault.
1: The processor has attempted to execute an undefined instruction.
When this bit is set to 1, the PC value stacked for the exception return points to the undefined instruction.
An undefined instruction is an instruction that the processor cannot decode.
• INVSTATE: Invalid State Usage Fault
This is part of
0: No invalid state usage fault.
1: The processor has attempted to execute an instruction that makes illegal use of the EPSR.
When this bit is set to 1, the PC value stacked for the exception return points to the instruction that attempted the illegal use of the
EPSR.
EPSR.
This bit is not set to 1 if an undefined instruction uses the EPSR.
• INVPC: Invalid PC Load Usage Fault
This is part of
0: No invalid PC load usage fault.
1: The processor has attempted an illegal load of EXC_RETURN to the PC, as a result of an invalid context, or an invalid
EXC_RETURN value.
EXC_RETURN value.
When this bit is set to 1, the PC value stacked for the exception return points to the instruction that tried to perform the illegal load
of the PC.
of the PC.
• NOCP: No Coprocessor Usage Fault
This is part of
0: No usage fault caused by attempting to access a coprocessor.
1: The processor has attempted to access a coprocessor.