Datasheet

ATmega8A [DATASHEET]

8159E–AVR–02/2013

Note: 1. The Boot Reset Address is shown in Table 24-6 on page 204. For the BOOTRST Fuse “1” means unprogrammed

while “0” means programmed.

The most typical and general program setup for the Reset and Interrupt Vector Addresses in ATmega8A is:

addressLabels Code Comments

$000 rjmp RESET ; Reset Handler

$001 rjmp EXT_INT0 ; IRQ0 Handler

$002 rjmp EXT_INT1 ; IRQ1 Handler

$003 rjmp TIM2_COMP ; Timer2 Compare Handler

$004 rjmp TIM2_OVF ; Timer2 Overflow Handler

$005 rjmp TIM1_CAPT ; Timer1 Capture Handler

$006 rjmp TIM1_COMPA ; Timer1 CompareA Handler

$007 rjmp TIM1_COMPB ; Timer1 CompareB Handler

$008 rjmp TIM1_OVF ; Timer1 Overflow Handler

$009 rjmp TIM0_OVF ; Timer0 Overflow Handler

$00a rjmp SPI_STC ; SPI Transfer Complete Handler

$00b rjmp USART_RXC ; USART RX Complete Handler

$00c rjmp USART_UDRE ; UDR Empty Handler

$00d rjmp USART_TXC ; USART TX Complete Handler

$00e rjmp ADC ; ADC Conversion Complete Handler

$00f rjmp EE_RDY ; EEPROM Ready Handler

$010 rjmp ANA_COMP ; Analog Comparator Handler

$011 rjmp TWSI ; Two-wire Serial Interface Handler

$012 rjmp SPM_RDY ; Store Program Memory Ready Handler

;

$013 RESET: ldi r16,high(RAMEND); Main program start

$014 out SPH,r16 ; Set Stack Pointer to top of RAM

$015 ldi r16,low(RAMEND)

$016 out SPL,r16

$017 sei ; Enable interrupts

$018 <instr> xxx

:. :. :.

Table 12-2. Reset and Interrupt Vectors Placement

BOOTRST

(1)

IVSEL Reset Address Interrupt Vectors Start Address

1 0 0x000 0x001

1 1 0x000 Boot Reset Address + 0x001

0 0 Boot Reset Address 0x001

0 1 Boot Reset Address Boot Reset Address + 0x001