Atmel ARM-Based Evaluation Kit AT91SAM9N12-EK AT91SAM9N12-EK Data Sheet

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SAM9N12/SAM9CN11/SAM9CN12 [DATASHEET]

11063K–ATARM–05-Nov-13

In all states, there are seven operation modes:



User mode is the usual ARM program execution state. It is used for executing most application programs



Fast Interrupt (FIQ) mode is used for handling fast interrupts. It is suitable for high-speed data transfer or channel 
process



Interrupt (IRQ) mode is used for general-purpose interrupt handling



Supervisor mode is a protected mode for the operating system



Abort mode is entered after a data or instruction prefetch abort



System mode is a privileged user mode for the operating system



Undefined mode is entered when an undefined instruction exception occurs

Mode changes may be made under software control, or may be brought about by external interrupts or exception
processing. Most application programs execute in User Mode. The non-user modes, known as privileged modes, are
entered in order to service interrupts or exceptions or to access protected resources.

The ARM9EJ-S core has a total of 37 registers.



31 general-purpose 32-bit registers 



6 32-bit status registers

 shows all the registers in all modes. 

R0

R0

R0

R0

R0

R0

R1

R1

R1

R1

R1

R1

R2

R2

R2

R2

R2

R2

R3

R3

R3

R3

R3

R3

R4

R4

R4

R4

R4

R4

R5

R5

R5

R5

R5

R5

R6

R6

R6

R6

R6

R6

R7

R7

R7

R7

R7

R7

R8

R8

R8

R8

R8

R8_FIQ

R9

R9

R9

R9

R9

R9_FIQ

R10

R10

R10

R10

R10

R10_FIQ

R11

R11

R11

R11

R11

R11_FIQ

R12

R12

R12

R12

R12

R12_FIQ

R13

R13_SVC

R13_ABORT

R13_UNDEF

R13_IRQ

R13_FIQ

R14

R14_SVC

R14_ABORT

R14_UNDEF

R14_IRQ

R14_FIQ

PC

PC

PC

PC

PC

PC

CPSR

CPSR

CPSR

CPSR

CPSR

CPSR

SPSR_SVC

SPSR_ABORT

SPSR_UNDEF

SPSR_IRQ

SPSR_FIQ

Mode-specific banked registers