Datasheet

61
7701F–AVR–10/12
Atmel ATtiny24/44/84 [Preliminary]
If a logic high level (logical one) is present on an asynchronous external interrupt pin config-
ured as "interrupt on rising edge, falling edge, or any logic change on pin" while the external
interrupt is not enabled, the corresponding external interrupt flag will be set when resuming
from the above mentioned sleep mode, as the clamping in these sleep mode produces the
requested logic change.
12.2.6 Unconnected Pins
If some pins are unused, it is recommended to ensure that these pins have a defined level.
Even though most of the digital inputs are disabled in the deep sleep modes as described
above, floating inputs should be avoided to reduce current consumption in all other modes
where the digital inputs are enabled (Reset, Active mode and Idle mode).
The simplest method to ensure a defined level of an unused pin is to enable the internal
pull-up. In this case, the pull-up will be disabled during reset. If low power consumption during
reset is important, it is recommended to use an external pull-up or pull-down. Connecting
unused pins directly to VCC or GND is not recommended, since this may cause excessive
currents if the pin is accidentally configured as an output.
12.3 Alternate Port Functions
Most port pins have alternate functions in addition to being general digital I/Os. Figure 12-5 on
page 62 shows how the port pin control signals from the simplified Figure 12-2 on page 57 can
be overridden by alternate functions. The overriding signals may not be present in all port pins,
but the figure serves as a generic description applicable to all port pins in the Atmel
®
AVR
®
microcontroller family.