Rainbow Electronics ATtiny43U - Manual (Page 67)

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8048B–AVR–03/09
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.
11.2.6 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, float-
ing 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 pulldown. Connecting unused pins
directly to V
CC
or GND is not recommended, since this may cause excessive currents if the pin is
accidentally configured as an output.
11.3 Alternate Port Functions
Most port pins have alternate functions in addition to being general digital I/Os. Figure 11-5 on
page 68 shows how the port pin control signals from the simplified Figure 11-2 on page 63 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 AVR microcon-
troller family.