Rainbow Electronics ATtiny10 - Manual (Page 30)

30
8127B–AVR–08/09
ATtiny4/5/9/10
Figure 8-5. Watchdog Reset During Operation
8.3 Watchdog Timer
The Watchdog Timer is clocked from an on-chip oscillator, which runs at 128 kHz. See Figure 8-
6 . By controlling the Watchdog Timer prescaler, the Watchdog Reset interval can be adjusted as
shown in Table 8-2 on page 32 . The WDR – Watchdog Reset – instruction resets the Watchdog
Timer. The Watchdog Timer is also reset when it is disabled and when a device reset occurs.
Ten different clock cycle periods can be selected to determine the reset period. If the reset
period expires without another Watchdog Reset, the ATtiny4/5/9/10 resets and executes from
the Reset Vector. For timing details on the Watchdog Reset, refer to
Table 8-3 on page 33 .
Figure 8-6. Watchdog Timer
The Wathdog Timer can also be configured to generate an interrupt instead of a reset. This can
be very helpful when using the Watchdog to wake-up from Power-down.
To prevent unintentional disabling of the Watchdog or unintentional change of time-out period,
two different safety levels are selected by the fuse WDTON as shown in
Table 8-1 on page 31 .
See “Procedure for Changing the Watchdog Timer Configuration” on page 31 for details.
CK
CC
OSC/2K OSC/4K OSC/8K
OSC/16K OSC/32K OSC/64K
OSC/128K OSC/256K OSC/512K OSC/1024K
MCU RESET
WATCHDOG
PRESCALER
128 kHz
OSCILLATOR
WATCHDOG
RESET
WDP0
WDP1
WDP2
WDP3
WDE
MUX