ATmega64A datasheet(61/392 Pages) ATMEL

61 / 392 page

8160C–AVR–07/09

ATmega64A

Notes:

1. When the BOOTRST Fuse is programmed, the device will jump to the Boot Loader address at

reset, see “Boot Loader Support – Read-While-Write Self-programming” on page 281.

2. When the IVSEL bit in MCUCR is set, Interrupt Vectors will be moved to the start of the Boot

Flash section. The address of each Interrupt Vector will then be address in this table added to

the start address of the Boot Flash section.

3. The Interrupts on address 0x0030 - 0x0044 do not exist in ATmega103 compatibility mode.

Table 11-2 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.

Note:

1. The Boot Reset Address is shown in Table 26-6 on page 292. 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

ATmega64A is:

Address Labels

Code

Comments

0x0000

jmp

RESET

; Reset Handler

0x0002

jmp

EXT_INT0

; IRQ0 Handler

0x0004

jmp

EXT_INT1

; IRQ1 Handler

0x0006

jmp

EXT_INT2

; IRQ2 Handler

0x0008

jmp

EXT_INT3

; IRQ3 Handler

0x000A

jmp

EXT_INT4

; IRQ4 Handler

0x000C

jmp

EXT_INT5

; IRQ5 Handler

0x000E

jmp

EXT_INT6

; IRQ6 Handler

0x0010

jmp

EXT_INT7

; IRQ7 Handler

0x0034(3)

TIMER3 COMPA

Timer/Counter3 Compare Match A

0x0036(3)

TIMER3 COMPB

Timer/Counter3 Compare Match B

0x0038(3)

TIMER3 COMPC

Timer/Counter3 Compare Match C

0x003A(3)

TIMER3 OVF

Timer/Counter3 Overflow

0x003C(3)

USART1, RX

USART1, Rx Complete

0x003E(3)

USART1, UDRE

USART1 Data Register Empty

0x0040(3)

USART1, TX

USART1, Tx Complete

0x0042(3)

TWI

Two-wire Serial Interface

0x0044(3)

SPM READY

Store Program Memory Ready

Table 11-2.

Reset and Interrupt Vectors Placement

(1)

BOOTRST

IVSEL

Reset Address

Interrupt Vectors Start Address

0x0000

0x0002

0x0000

Boot Reset Address + 0x0002

Boot Reset Address

0x0002

Boot Reset Address

Boot Reset Address + 0x0002

Table 11-1.

Reset and Interrupt Vectors (Continued)

Vector

No.

Program

Address(2)

Source

Interrupt Definition

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