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ManualsBrandsMICROCHIP TECHNOLOGY ManualsMicrocontrollers, Microprocessors & QuartzesEmbedded microcontroller QFN 64 (9x9) 8-Bit 16 MHz I/O number 54
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7
2549PS–AVR–10/2012
ATmega640/1280/1281/2560/2561
2.2 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. Table 2-1 summarizes the different configurations for the six devices.
2.3 Pin Descriptions
2.3.1 VCC
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
ATmega640/1280/1281/2560/2561 as listed on page 78.
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
ATmega640/1280/1281/2560/2561 as listed on page 79.
2.3.5 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
Table 2-1. Configuration Summary
Device Flash EEPROM RAM
General
Purpose I/O pins
16 bits resolution
PWM channels
Serial
USARTs
ADC
Channels
ATmega640 64KB 4KB 8KB 86 12 4 16
ATmega1280 128KB 4KB 8KB 86 12 4 16
ATmega1281 128KB 4KB 8KB 54 6 2 8
ATmega2560 256KB 4KB 8KB 86 12 4 16
ATmega2561 256KB 4KB 8KB 54 6 2 8