
129
XMEGA A [MANUAL]
8077I–AVR–11/2012
interrupt vector address for the last acknowledged low-level interrupt will have the lowest priority the next time one or
more interrupts from the low level is requested.
Figure 12-4. Round-robin scheduling.
12.7
Interrupt Vector Locations
Table 12-2 on page 129 shows reset and Interrupt vectors placement for the various combinations of BOOTRST and
IVSEL settings. If the program never enables an interrupt source, the Interrupt Vectors are not used, and regular program
code can be placed at these locations. This is also the case if the Reset Vector is in the Application section while the
Interrupt Vectors are in the Boot section or vice versa.
Table 12-2. Reset and interrupt vectors placement.
Highest Priority
IV EC 0
:
IV EC x
IV EC x+1
:
IV EC N
IV EC 0
:
IV EC x
IV EC x+1
:
IV EC N
Highest Priority
Low est Priority
IV EC x+2
IV EC x+1 las t ack now le dge d
inte rrupt
Low est Priority
IV EC x las t ack now le dge d
inte rrupt
BOOTRST
IVSEL
Reset address
Interrupt vectors start address
1
0
0x0000
0x0002
1
0x0000
Boot Reset Address + 0x0002
0
Boot Reset Address
0x0002
0
1
Boot Reset Address
Boot Reset Address + 0x0002