ATMEga64L ATMEL Corporation, ATMEga64L Datasheet - Page 62

• Manufacturer Part Number: ATMEga64L
• Description: 8-bit AVR Microcontroller with 64K Bytes In-System Programmable Flash
• Manufacturer: ATMEL Corporation

Moving Interrupts Between
Application and Boot Space
MCU Control Register –
MCUCR
62
ATmega64(L)
When the BOOTRST Fuse is programmed and the Boot section size set to 8K bytes, the
most typical and general program setup for the Reset and Interrupt Vector Addresses is:
When the BOOTRST Fuse is programmed, the Boot section size set to 8K bytes and the
IVSEL bit in the MCUCR Register is set before any interrupts are enabled, the most typ-
ical and general program setup for the Reset and Interrupt Vector Addresses is:
The General Interrupt Control Register controls the placement of the Interrupt Vector
table.
• Bit 1 – IVSEL: Interrupt Vector Select
When the IVSEL bit is cleared (zero), the Interrupt Vectors are placed at the start of the
Flash memory. When this bit is set (one), the Interrupt Vectors are moved to the begin-
ning of the Boot Loader section of the Flash. The actual address of the start of the Boot
Flash section is determined by the BOOTSZ Fuses. Refer to the section “Boot Loader
Support – Read-While-Write Self-programming” on page 277 for details. To avoid unin-
tentional changes of Interrupt Vector tables, a special write procedure must be followed
to change the IVSEL bit:
Bit
Read/Write
Initial Value
Address Labels Code
.org 0x0002
0x0002
0x0004
...
0x0044
;
.org 0x7000
0x7000 RESET: ldi
0x7001
0x7002
0x7003
0x7004
0x7005
Address Labels Code
;
.org 0x7000
0x7000
0x7002
0x7004
...
0x7044
0x7046 RESET: ldi
0x7047
0x7048
0x7049
0x704A
0x704B
SRE
R/W
7
0
jmp
jmp
...
jmp
out
ldi
out
sei
<instr>
jmp
jmp
jmp
...
jmp
out
ldi
out
sei
<instr>
SRW10
R/W
6
0
EXT_INT0 ; IRQ0 Handler
EXT_INT1 ; IRQ1 Handler
...
SPM_RDY
r16,high(RAMEND); Main program start
SPH,r16
r16,low(RAMEND)
SPL,r16
RESET
EXT_INT0 ; IRQ0 Handler
EXT_INT1 ; IRQ1 Handler
...
SPM_RDY ; Store Program Memory Ready Handler
r16,high(RAMEND); Main program start
SPH,r16
r16,low(RAMEND)
SPL,r16
xxx
xxx
R/W
SE
5
0
;
; Store Program Memory Ready Handler
; Set Stack Pointer to top of RAM
; Enable interrupts
; Reset handler
;
; Set Stack Pointer to top of RAM
; Enable interrupts
SM1
R/W
4
0
Comments
Comments
SM0
R/W
3
0
SM2
R/W
2
0
IVSEL
R/W
1
0
IVCE
R/W
0
0
2490G–AVR–03/04
MCUCR