Datasheet

6
2552KS–AVR–04/11
ATmega329/3290/649/6490
2.2 Comparison between ATmega329, ATmega3290, ATmega649 and ATmega6490
The ATmega329, ATmega3290, ATmega649, and ATmega6490 differs only in memory sizes,
pin count and pinout. Table 2-1 on page 6 summarizes the different configurations for the four
devices.
2.3 Pin Descriptions
The following section describes the I/O-pin special functions.
2.3.1 V
CC
Digital supply voltage.
2.3.2 GND
Ground.
2.3.3 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.
2.3.4 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.
Table 2-1. Configuration Summary
Device Flash EEPROM RAM
LCD
Segments
General Purpose
I/O Pins
ATmega329 32Kbytes 1Kbytes 2Kbytes 4 x 25 54
ATmega3290 32Kbytes 1K bytes 2Kbytes 4 x 40 69
ATmega649 64Kbytes 2Kbytes 4Kbytes 4 x 25 54
ATmega6490 64Kbytes 2Kbytes 4Kbytes 4 x 40 69