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108
8210C–AVR–09/11
Atmel AVR XMEGA D
10.8.2
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.
10.8.3
CTRL – Control register
• Bit 7 – RREN: Round-robin Scheduling Enable
When the RREN bit is set, the round-robin scheduling scheme is enabled for low-level interrupts.
When this bit is cleared, the priority is static according to interrupt vector address, where the low-
est address has the highest priority.
• Bit 6 – IVSEL: Interrupt Vector Select
When the IVSEL bit is cleared (zero), the interrupt vectors are placed at the start of the applica-
tion section in flash. When this bit is set (one), the interrupt vectors are placed in the beginning
of the boot section of the flash. Refer to the device datasheet for the absolute address.
This bit is protected by the configuration change protection mechanism. Refer to
for details.
• Bit 5:3 – 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 – HILVLEN: High-level Interrupt Enable
When this bit is set, all high-level interrupts are enabled. If this bit is cleared, high-level interrupt
requests will be ignored.
• Bit 1 – MEDLVLEN: Medium-level Interrupt Enable
When this bit is set, all medium-level interrupts are enabled. If this bit is cleared, medium-level
interrupt requests will be ignored.
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
Bit
7
6
5
4
3
2
1
0
RREN
IVSEL
–
–
–
HILVLEN
MEDLVLEN
LOLVLEN
CTRL
Read/Write R/W
R/W
R
R
R
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0