attiny11 ATMEL Corporation, attiny11 Datasheet - Page 21

• Manufacturer Part Number: attiny11
• Description: 8-bit Microcontroller With 1k Byte Flash
• Manufacturer: ATMEL Corporation

ATtiny11/12
reset (if enabled), an external level interrupt (INT0), or a pin change interrupt can wake
up the MCU.
Note that if a level triggered or pin change interrupt is used for wake-up from Power-
down Mode, the changed level must be held for a time to wake up the MCU. This makes
the MCU less sensitive to noise. The wake-up period is equal to the clock-counting part
of the reset period (See Table 10). The MCU will wake up from the power-down if the
input has the required level for two watchdog oscillator cycles. If the wake-up period is
shorter than two watchdog oscillator cycles, the MCU will wake up if the input has the
required level for the duration of the wake-up period. If the wake-up condition disap-
pears before the wake-up period has expired, the MCU will wake up from power-down
without executing the corresponding interrupt. The period of the watchdog oscillator is
2.7 µs (nominal) at 3.0V and 25°C. The frequency of the watchdog oscillator is voltage
dependent as shown in the section “ATtiny11 Typical Characteristics” on page 62.
When waking up from Power-down Mode, there is a delay from the wake-up condition
occurs until the wake-up becomes effective. This allows the clock to restart and become
stable after having been stopped. The wake-up period is defined by the same CKSEL
fuses that define the reset time-out period.
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