Datasheet

6
ATmega329/3290/649/6490
2552I–AVR–04/07
Comparison between
ATmega329,
ATmega3290,
ATmega649 and
ATmega6490
The ATmega329, ATmega3290, ATmega649, and ATmega6490 differs only in memory
sizes, pin count and pinout. Table 1 on page 6 summarizes the different configurations
for the four devices.
Pin Descriptions The following section describes the I/O-pin special functions.
V
CC
Digital supply voltage.
GND Ground.
Port A (PA7..PA0) Port A is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each
bit). The Port A output buffers have symmetrical drive characteristics with both high sink
and source capability. As inputs, Port A pins that are externally pulled low will source
current if the pull-up resistors are activated. The Port A pins are tri-stated when a reset
condition becomes active, even if the clock is not running.
Port A also serves the functions of various special features of the
ATmega329/3290/649/6490 as listed on page 67.
Port B (PB7..PB0) Port B is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each
bit). The Port B output buffers have symmetrical drive characteristics with both high sink
and source capability. As inputs, Port B pins that are externally pulled low will source
current if the pull-up resistors are activated. The Port B pins are tri-stated when a reset
condition becomes active, even if the clock is not running.
Port B has better driving capabilities than the other ports.
Port B also serves the functions of various special features of the
ATmega329/3290/649/6490 as listed on page 68.
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 ATmega329/3290/649/6490
as listed on page 71.
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.
Table 1. Configuration Summary
Device Flash EEPROM RAM
LCD
Segments
General Purpose
I/O Pins
ATmega329 32K bytes 1K bytes 2K bytes 4 x 25 54
ATmega3290 32K bytes 1K bytes 2K bytes 4 x 40 69
ATmega649 64K bytes 2K bytes 4K bytes 4 x 25 54
ATmega6490 64K bytes 2K bytes 4K bytes 4 x 40 69