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ATmega8A [DATASHEET]
8159E–AVR–02/2013
12. Interrupts
This section describes the specifics of the interrupt handling performed by the ATmega8A. For a general explana-
12.1
Interrupt Vectors in ATmega8A
Notes:
1. When the BOOTRST Fuse is programmed, the device will jump to the Boot Loader address at reset, see
“Boot2. When the IVSEL bit in GICR is set, Interrupt Vectors will be moved to the start of the boot Flash section. The
address of each Interrupt Vector will then be the address in this table added to the start address of the boot Flash
section.
Table 12-2 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 12-1.
Reset and Interrupt Vectors
Vector No.
Program
Source
Interrupt Definition
1
RESET
External Pin, Power-on Reset, Brown-out Reset,
and Watchdog Reset
2
0x001
INT0
External Interrupt Request 0
3
0x002
INT1
External Interrupt Request 1
4
0x003
TIMER2 COMP
Timer/Counter2 Compare Match
5
0x004
TIMER2 OVF
Timer/Counter2 Overflow
6
0x005
TIMER1 CAPT
Timer/Counter1 Capture Event
7
0x006
TIMER1 COMPA
Timer/Counter1 Compare Match A
8
0x007
TIMER1 COMPB
Timer/Counter1 Compare Match B
9
0x008
TIMER1 OVF
Timer/Counter1 Overflow
10
0x009
TIMER0 OVF
Timer/Counter0 Overflow
11
0x00A
SPI, STC
Serial Transfer Complete
12
0x00B
USART, RXC
USART, Rx Complete
13
0x00C
USART, UDRE
USART Data Register Empty
14
0x00D
USART, TXC
USART, Tx Complete
15
0x00E
ADC
ADC Conversion Complete
16
0x00F
EE_RDY
EEPROM Ready
17
0x010
ANA_COMP
Analog Comparator
18
0x011
TWI
Two-wire Serial Interface
19
0x012
SPM_RDY
Store Program Memory Ready