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The Stop condition provides a Timer Enable/Disable function. The CK down-divided modes are scaled directly from the CK
oscillator clock. If the external pin modes are used for Timer/Counter0, transitions on PB2/(T0) will clock the counter even if
the pin is configured as an output. This feature can give the user SW control of the counting.
Timer Counter 0 – TCNT0
Bit
7
$32
MSB
Read/Write
R/W
Initial value
0
The Timer/Counter0 is implemented as an up-counter with read and write access. If the Timer/Counter0 is written and a
clock source is present, the Timer/Counter0 continues counting in the timer clock cycle following the write operation.
Watchdog Timer
The Watchdog Timer is clocked from a separate on-chip oscillator. By controlling the Watchdog Timer prescaler, the
Watchdog reset interval can be adjusted as shown in Table 16. See characterization data for typical values at other V
levels. The WDR – Watchdog Reset – instruction resets the Watchdog Timer. Eight different clock cycle periods can be
selected to determine the reset period. If the reset period expires without another Watchdog reset, the ATtiny10/11/12
resets and executes from the reset vector. For timing details on the Watchdog reset, refer to page 22.
To prevent unintentional disabling of the watchdog, a special turn-off sequence must be followed when the watchdog is
disabled. Refer to the description of the Watchdog Timer Control Register for details.
Figure 25. Watchdog Timer
6
5
4
R/W
R/W
R/W
0
0
0
Oscillator
1 MHz at V
= 5V
CC
350 kHz at V
= 3V
CC
110 kHz at V
= 2V
CC
3
2
1
R/W
R/W
R/W
0
0
0
ATtiny10/11/12
0
LSB
TCNT0
R/W
0
CC
31
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