ATmega640/1280/1281/2560/2561
3.2
Comparison Between ATmega1281/2561 and ATmega640/1280/2560
Each device in the ATmega640/1280/1281/2560/2561 family differs only in memory size and
number of pins.
summarizes the different configurations for the six devices.
Table 3-1.
Device
ATmega640
ATmega1280
ATmega1281
ATmega2560
ATmega2561
Configuration Summary
Flash
64KB
128KB
128KB
256KB
256KB
EEPROM
4KB
4KB
4KB
4KB
4KB
RAM
8KB
8KB
8KB
8KB
8KB
General
Purpose I/O pins
86
86
54
86
54
16 bits resolution
PWM channels
12
12
6
12
6
Serial
USARTs
4
4
2
4
2
ADC
Channels
16
16
8
16
8
3.3
3.3.1
Pin Descriptions
VCC
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
ATmega640/1280/1281/2560/2561 as listed on
special
features
of
the
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
ATmega640/1280/1281/2560/2561 as listed on
special
features
of
the
3.3.5
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
7
2549L–AVR–08/07
ATMEL [ ATMEL CORPORATION ]
