6

ATmega64(L)

2490LS–AVR–10/06

Port C (PC7..PC0)

Port C is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each

bit). The Port C output buffers have symmetrical drive characteristics with both high sink

and source capability. As inputs, Port C pins that are externally pulled low will source

current if the pull-up 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 ATmega64 as listed on page

78. In ATmega103 compatibility mode, Port C is output only, and the port C pins are not

tri-stated when a reset condition becomes active.

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 special features of the ATmega64 as listed

on page 79.

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 special features of the ATmega64 as listed

on page 82.

Port F (PF7..PF0)

Port F serves as the 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 symmetrical 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 resis-

tors on pins PF7(TDI), PF5(TMS) and PF4(TCK) will be activated even if a reset occurs.

The TDO pin is tri-stated unless TAP states that shift out data are entered.

Port F also serves the functions of the JTAG interface.

In ATmega103 compatibility mode, Port F is an input port only.

Port G (PG4..PG0)

Port G is a 5-bit bi-directional 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 special features.

In ATmega103 compatibility mode, these pins only serves as strobes signals to the

external memory as well as input to the 32 kHz Oscillator, and the pins are initialized to

PG0 = 1, PG1 = 1, and PG2 = 0 asynchronously when a reset condition becomes

active, even if the clock is not running. PG3 and PG4 are Oscillator pins.