Atmel ARM-Based Evaluation Kit for SAM4S16C, 32-Bit ARM® Cortex® Microcontroller ATSAM4S-WPIR-RD ATSAM4S-WPIR-RD Ficha De Dados

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SAM4S Series [DATASHEET]

Atmel-11100G-ATARM-SAM4S-Datasheet_27-May-14

1: Unstack for an exception return has caused one or more bus faults.
This fault is chained to the handler. This means that when the processor sets this bit to 1, the original return stack is still 

present. The processor does not adjust the SP from the failing return, does not performed a new save, and does not write 

a fault address to the BFAR.

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 incor-

rect. The processor does not write a fault address to the SCB_BFAR. 

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.
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.

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.

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.
This bit is not set to 1 if an undefined instruction uses the EPSR.

This is part of 

. It is caused by an invalid PC load by EXC_RETURN:

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. 
When this bit is set to 1, the PC value stacked for the exception return points to the instruction that tried to perform the ille-

gal load of the PC.