ATmega640/1280/1281/2560/2561
resistors are activated. The Port C pins are tri-stated when a reset condition becomes active,
even if the clock is not running.
Port C also serves the functions of special features of the ATmega640/1280/1281/2560/2561 as
listed on
page 82.
2.3.6
Port D (PD7..PD0)
Port D is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The
Port D output buffers have symmetrical drive characteristics with both high sink and source
capability. As inputs, Port D pins that are externally pulled low will source current if the pull-up
resistors are activated. The Port D pins are tri-stated when a reset condition becomes active,
even if the clock is not running.
Port D also serves the functions of various
ATmega640/1280/1281/2560/2561 as listed on
page 83.
2.3.7
special
features
of
the
Port E (PE7..PE0)
Port E is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The
Port E output buffers have symmetrical drive characteristics with both high sink and source
capability. As inputs, Port E pins that are externally pulled low will source current if the pull-up
resistors are activated. The Port E pins are tri-stated when a reset condition becomes active,
even if the clock is not running.
Port E also serves the functions of various
ATmega640/1280/1281/2560/2561 as listed on
page 86.
special
features
of
the
2.3.8
Port F (PF7..PF0)
Port F serves as analog inputs to the A/D Converter.
Port F also serves as an 8-bit bi-directional I/O port, if the A/D Converter is not used. Port pins
can provide internal pull-up resistors (selected for each bit). The Port F output buffers have sym-
metrical drive characteristics with both high sink and source capability. As inputs, Port F pins
that are externally pulled low will source current if the pull-up resistors are activated. The Port F
pins are tri-stated when a reset condition becomes active, even if the clock is not running. If the
JTAG interface is enabled, the pull-up resistors on pins PF7(TDI), PF5(TMS), and PF4(TCK) will
be activated even if a reset occurs.
Port F also serves the functions of the JTAG interface.
2.3.9
Port G (PG5..PG0)
Port G is a 6-bit I/O port with internal pull-up resistors (selected for each bit). The Port G output
buffers have symmetrical drive characteristics with both high sink and source capability. As
inputs, Port G pins that are externally pulled low will source current if the pull-up resistors are
activated. The Port G pins are tri-stated when a reset condition becomes active, even if the clock
is not running.
Port G also serves the functions of various
ATmega640/1280/1281/2560/2561 as listed on
page 90.
special
features
of
the
2.3.10
Port H (PH7..PH0)
Port H is a 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The
Port H output buffers have symmetrical drive characteristics with both high sink and source
capability. As inputs, Port H pins that are externally pulled low will source current if the pull-up
8
2549MS–AVR–09/10
ATMEL [ ATMEL CORPORATION ]
