attiny13-20ss ATMEL Corporation, attiny13-20ss Datasheet - Page 34

• Manufacturer Part Number: attiny13-20ss
• Description: 8-bit Microcontroller With 1k Bytes In-system Programmable Flash - Atmel Corporation
• Manufacturer: ATMEL Corporation

Watchdog Reset
MCU Status Register –
MCUSR
34
ATtiny13
Figure 17. Brown-out Reset During Operation
When the Watchdog times out, it will generate a short reset pulse of one CK cycle dura-
tion. On the falling edge of this pulse, the delay timer starts counting the Time-out period
t
Figure 18. 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 ATtiny13 and will 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.
• Bit 2 – BORF: Brown-out Reset Flag
This bit is set if a Brown-out Reset occurs. The bit is reset by a Power-on Reset, or by
writing a logic zero to the flag.
• Bit 1 – EXTRF: External Reset Flag
TOUT
Bit
Read/Write
Initial Value
. Refer to page 42 for details on operation of the Watchdog Timer.
CC
INTERNAL
TIME-OUT
RESET
RESET
V
R
7
–
0
CC
R
6
–
0
R
5
–
0
V
CK
BOT-
R
4
–
0
WDRF
R/W
3
See Bit Description
BORF
R/W
V
t
2
TOUT
BOT+
EXTRF
R/W
1
PORF
R/W
2535G–AVR–01/07
0
MCUSR