ATMEGA163 ATMEL [ATMEL Corporation], ATMEGA163 Datasheet - Page 23

• Manufacturer Part Number: ATMEGA163
• Description: 8-bit Microcontroller with 16K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

Reset Sources
1142E–AVR–02/03
When the BOOTRST Fuse is programmed and the Boot section size set to 512 bytes,
the most typical and general program setup for the Reset and Interrupt Vector
Addresses in ATmega163 is:
The ATmega163 has four sources of reset:
•
•
•
•
During Reset, all I/O Registers are set to their initial values, and the program starts exe-
cution from address $000 (unless the BOOTRST Fuse is programmed, as explained
above). The instruction placed in this address location must be a JMP – absolute jump –
instruction to the reset handling routine. If the program never enables an interrupt
source, the Interrupt Vectors are not used, and regular program code can be placed at
these locations. The circuit diagram in Figure 24 shows the Reset Logic. Table 4 and
Table 5 define the timing and electrical parameters of the reset circuitry.
Address
$002
...
$022
;
$024
$025
$026
$027
$028
;
.org $1f00
$1f00
Power-on Reset. The MCU is reset when the supply voltage is below the Power-on
Reset threshold (V
External Reset. The MCU is reset when a low level is present on the RESET pin for
more than 500 ns.
Watchdog Reset. The MCU is reset when the Watchdog Timer period expires and
the Watchdog is enabled.
Brown-out Reset. The MCU is reset when the supply voltage V
Brown-out Reset threshold (V
...
Labels Code
MAIN:
jmp
...
jmp
ldi
out
ldi
out
<instr> xxx
jmp
POT
).
EXT_INT0
TWI
r16,high(RAMEND) ; Main program start
SPH,r16
r16,low(RAMEND)
SPL,r16
RESET
BOT
).
; Two-wire Serial Interface Interrupt Handler
Comments
; IRQ0 Handler
; Set stack pointer to top of RAM
; Reset Handler
ATmega163(L)
CC
is below the
23