ATMEGA163 ATMEL [ATMEL Corporation], ATMEGA163 Datasheet - Page 28

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

Watchdog Reset
MCU Status Register –
MCUSR
28
ATmega163(L)
Figure 28. Brown-out Reset During Operation
The hysteresis on V
When the Watchdog times out, it will generate a short reset pulse of 1 XTAL cycle dura-
tion. On the falling edge of this pulse, the delay timer starts counting the Time-out Period
t
Figure 29. Watchdog Reset During Operation
The MCU Status Register provides information on which reset source caused an MCU
Reset.
• Bits 7..4 – Res: Reserved Bits
These bits are reserved bits in the ATmega163 and always read as zero.
• Bit 3 – WDRF: Watchdog Reset Flag
This bit is set if a Watchdog Reset occurs. The bit is reset by a Power-on Reset, or by
writing a logic zero to the Flag.
TOUT
Bit
$34 ($54)
Read/Write
Initial Value
. Refer to page 60 for details on operation of the Watchdog Timer.
INTERNAL
TIME-OUT
RESET
RESET
VCC
R
7
–
0
BOT
: V
6
–
R
0
BOT+
= V
R
5
–
0
1 CK Cycle
V
BOT
BOT-
+ 25 mV, V
R
4
–
0
WDRF
R/W
BOT-
3
= V
BORF
R/W
BOT
V
t
2
TOUT
BOT+
See Bit Description
- 25 mV
EXTRF
R/W
1
PORF
R/W
1142E–AVR–02/03
0
MCUSR