ATmega48/88/168
Interrupts
This section describes the specifics of the interrupt handling as performed in
ATmega48/88/168. For a general explanation of the AVR interrupt handling, refer to
“Reset and Interrupt Handling” on page 12.
The interrupt vectors in ATmega48, ATmega88 and ATmega168 are generally the
same, with the following differences:
•
Each Interrupt Vector occupies two instruction words in ATmega168, and one
instruction word in ATmega48 and ATmega88.
•
ATmega48 does not have a separate Boot Loader Section. In ATmega88 and
ATmega168, the Reset Vector is affected by the BOOTRST fuse, and the Interrupt
Vector start address is affected by the IVSEL bit in MCUCR.
Interrupt Vectors in ATmega48
Table 26. Reset and Interrupt Vectors in ATmega48
Vector No. Program Address Source
Interrupt Definition
External Pin, Power-on Reset, Brown-out Reset and Watchdog System Reset
External Interrupt Request 0
External Interrupt Request 1
Pin Change Interrupt Request 0
Pin Change Interrupt Request 1
Pin Change Interrupt Request 2
Watchdog Time-out Interrupt
Timer/Counter2 Compare Match A
Timer/Counter2 Compare Match B
Timer/Counter2 Overflow
1
0x000
0x001
0x002
0x003
0x004
0x005
0x006
0x007
0x008
0x009
0x00A
0x00B
0x00C
0x00D
0x00E
0x00F
0x010
0x011
0x012
0x013
0x014
0x015
0x016
0x017
0x018
0x019
RESET
2
INT0
3
INT1
4
PCINT0
5
PCINT1
6
PCINT2
7
WDT
8
TIMER2 COMPA
TIMER2 COMPB
TIMER2 OVF
TIMER1 CAPT
TIMER1 COMPA
TIMER1 COMPB
TIMER1 OVF
TIMER0 COMPA
TIMER0 COMPB
TIMER0 OVF
SPI, STC
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
Timer/Counter1 Capture Event
Timer/Counter1 Compare Match A
Timer/Coutner1 Compare Match B
Timer/Counter1 Overflow
Timer/Counter0 Compare Match A
Timer/Counter0 Compare Match B
Timer/Counter0 Overflow
SPI Serial Transfer Complete
USART Rx Complete
USART, RX
USART, UDRE
USART, TX
ADC
USART, Data Register Empty
USART, Tx Complete
ADC Conversion Complete
EEPROM Ready
EE READY
ANALOG COMP
TWI
Analog Comparator
2-wire Serial Interface
SPM READY
Store Program Memory Ready
51
2545D–AVR–07/04
ATMEL [ ATMEL ]
