ATmega32A datasheet(55/352 Pages) ATMEL

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8155B–AVR–07/09

ATmega32A

above mentioned sleep modes, as the clamping in these sleep modes produces the requested

logic change.

12.2.4

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 pullup.

In this case, the pullup will be disabled during reset. If low power consumption during reset is

important, it is recommended to use an external pullup 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.

12.3

Alternate Port Functions

Most port pins have alternate functions in addition to being General Digital I/Os. Figure 12-5

shows how the port pin control signals from the simplified Figure 12-2 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 microcontroller family.

ATmega32A 데이터시트(PDF) 55 Page - ATMEL Corporation