ATMEGA329_071 datasheet(6/29 Pages) ATMEL | 8-bit Microcontroller with In-System Programmable Flash

6 page

2552JS–AVR–08/07

ATmega329/3290/649/6490

3.2

Comparison between ATmega329, ATmega3290, ATmega649 and ATmega6490

The ATmega329, ATmega3290, ATmega649, and ATmega6490 differs only in memory sizes,

pin count and pinout. Table 3-1 on page 6 summarizes the different configurations for the four

devices.

3.3

Pin Descriptions

The following section describes the I/O-pin special functions.

3.3.1

Digital supply voltage.

3.3.2

GND

Ground.

3.3.3

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.

3.3.4

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 3-1.

Configuration Summary

Device

Flash

EEPROM

RAM

LCD

Segments

General Purpose

I/O Pins

ATmega329

32K bytes

1K bytes

2K bytes

4 x 25

ATmega3290

32K bytes

1K bytes

2K bytes

4 x 40

ATmega649

64K bytes

2K bytes

4K bytes

4 x 25

ATmega6490

64K bytes

2K bytes

4K bytes

4 x 40

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