141
8331B–AVR–03/12
Atmel AVR XMEGA AU
12.8
Register Description
12.8.1
STATUS – Status register
• Bit 7 – NMIEX: Non-Maskable Interrupt Executing
This flag is set if a non-maskable interrupt is executing. The flag will be cleared when returning
(RETI) from the interrupt handler.
• Bit 6:3 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always
write these bits to zero when this register is written.
• Bit 2 – HILVLEX: High-level Interrupt Executing
This flag is set when a high-level interrupt is executing or when the interrupt handler has been
interrupted by an NMI. The flag will be cleared when returning (RETI) from the interrupt handler.
• Bit 1 – MEDLVLEX: Medium-level Interrupt Executing
This flag is set when a medium-level interrupt is executing or when the interrupt handler has
been interrupted by an interrupt from higher level or an NMI. The flag will be cleared when
returning (RETI) from the interrupt handler.
• Bit 0 – LOLVLEX: Low-level Interrupt Executing
This flag is set when a low-level interrupt is executing or when the interrupt handler has been
interrupted by an interrupt from higher level or an NMI. The flag will be cleared when returning
(RETI) from the interrupt handler.
12.8.2
INTPRI – Interrupt priority register
• Bit 7:0 – INTPRI: Interrupt Priority
When round-robin scheduling is enabled, this register stores the interrupt vector of the last
acknowledged low-level interrupt. The stored interrupt vector will have the lowest priority the
next time one or more low-level interrupts are pending. The register is accessible from software
to change the priority queue. This register is not reinitialized to its initial value if round-robing
scheduling is disabled, and so if default static priority is needed, the register must be written to
zero.
Bit
7
6
5
4
3
2
1
0
NMIEX
–
–
–
–
HILVLEX
MEDLVLEX
LOLVLEX
STATUS
Read/Write
R
R
R
R
R
R
R
R
Initial Value
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
INTPRI[7:0]
INTPRI
Read/Write R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0