Datasheet

ATmega640/1280/1281/2560/2561

2549K–AVR–01/07

Port K is a 8-bit bi-directional I/O port with internal pull-up resistors (selected for each

bit). The Port K output buffers have symmetrical drive characteristics with both high sink

and source capability. As inputs, Port K pins that are externally pulled low will source

current if the pull-up resistors are activated. The Port K pins are tri-stated when a reset

condition becomes active, even if the clock is not running.

Port K also serves the functions of various special features of the

ATmega640/1280/2560 as listed on page 111.

Port L (PL7..PL0) Port L is a 8-bit bi-directional I/O port with internal pull-up resistors (selected for each

bit). The Port L output buffers have symmetrical drive characteristics with both high sink

and source capability. As inputs, Port L pins that are externally pulled low will source

current if the pull-up resistors are activated. The Port L pins are tri-stated when a reset

condition becomes active, even if the clock is not running.

Port L also serves the functions of various special features of the

ATmega640/1280/2560 as listed on page 113.

RESET

Reset input. A low level on this pin for longer than the minimum pulse length will gener-

ate a reset, even if the clock is not running. The minimum pulse length is given in Table

26 on page 58. Shorter pulses are not guaranteed to generate a reset.

XTAL1 Input to the inverting Oscillator amplifier and input to the internal clock operating circuit.

XTAL2 Output from the inverting Oscillator amplifier.

AVCC AVCC is the supply voltage pin for Port F and the A/D Converter. It should be externally

connected to V

, even if the ADC is not used. If the ADC is used, it should be con-

nected to V

through a low-pass filter.

AREF This is the analog reference pin for the A/D Converter.

Resources

A comprehensive set of development tools and application notes, and datasheets are

available for download on http://www.atmel.com/avr.

About Code Examples

This documentation contains simple code examples that briefly show how to use various

parts of the device. Be aware that not all C compiler vendors include bit definitions in the

header files and interrupt handling in C is compiler dependent. Please confirm with the

C compiler documentation for more details.

These code examples assume that the part specific header file is included before com-

pilation. For I/O registers located in extended I/O map, "IN", "OUT", "SBIS", "SBIC",

"CBI", and "SBI" instructions must be replaced with instructions that allow access to

extended I/O. Typically "LDS" and "STS" combined with "SBRS", "SBRC", "SBR", and

"CBR".