ATMEGA325-16AJ ATMEL [ATMEL Corporation], ATMEGA325-16AJ Datasheet - Page 6

• Manufacturer Part Number: ATMEGA325-16AJ
• Description: 8-bit Microcontroller with In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

Comparison between
ATmega325,
ATmega3250,
ATmega645 and
ATmega6450
Pin Descriptions
V
GND
Port A (PA7..PA0)
Port B (PB7..PB0)
Port C (PC7..PC0)
Port D (PD7..PD0)
Port E (PE7..PE0)
6
CC
ATmega325/3250/645/6450
The ATmega325, ATmega3250, ATmega645, and ATmega6450 differs only in memory
sizes, pin count and pinout. Table 1 on page 6 summarizes the different configurations
for the four devices.
Table 1. Configuration Summary
The following section describes the I/O-pin special functions.
Digital supply voltage.
Ground.
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 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.
P o r t B a l s o s e r v e s t h e f u n c t i o n s o f v a r i o u s s p e c i a l f e a t u r e s o f t h e
ATmega325/3250/645/6450 as listed on page 59.
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 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.
P o r t D a l s o s e r v e s t h e f u n c t i o n s o f v a r i o u s s p e c i a l f e a t u r e s o f t h e
ATmega325/3250/645/6450 as listed on page 62.
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
Device
ATmega325
ATmega3250
ATmega645
ATmega6450
Flash
32K bytes
32K bytes
64K bytes
64K bytes
EEPROM
1K bytes
1K bytes
2K bytes
2K bytes
RAM
2K bytes
2K bytes
4K bytes
4K bytes
General Purpose
I/O Pins
53
68
53
68
2570A–AVR–09/04