142
8331B–AVR–03/12
Atmel AVR XMEGA AU
12.8.3
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 0 – LOLVLEN: Low-level Interrupt Enable
When this bit is set, all low-level interrupts are enabled. If this bit is cleared, low-level interrupt
requests will be ignored.
Note:
1. Ignoring interrupts will be effective one cycle after the bit is cleared.
12.9
Register Summary
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
Address
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Page
+0x00
STATUS
NMIEX
–
–
–
–
HILVLEX
MEDLVLEX
LOLVLEX
+0x01
INTPRI
INTPRI[7:0]
+0x02
CTRL
RREN
IVSEL
–
–
–
HILVLEN
MEDLVLEN
LOLVLEN