5

8393CS-MCU Wireless-09/14

ATmega256/128/64RFR2

The device is manufactured using Atmel’s high-density nonvolatile memory technology.

The On-chip ISP Flash allows the program memory to be reprogrammed in-system

trough an SPI serial interface, by a conventional nonvolatile memory programmer, or by

on on-chip boot program running on the AVR core. The boot program can use any

interface to download the application program in the application Flash memory.

Software in the boot Flash section will continue to run while the application Flash

section is updated, providing true Read-While-Write operation. By combining an 8 bit

RISC CPU with In-System Self-Programmable Flash on a monolithic chip, the Atmel

ATmega256/128/64RFR2 is a powerful microcontroller that provides a highly flexible

and cost effective solution to many embedded control applications.

The ATmega256/128/64RFR2 AVR is supported with a full suite of program and system

development

tools

including:

C

compiler,

macro

assemblers,

program

debugger/simulators, in-circuit emulators, and evaluation kits.

3.2 Pin Descriptions

3.2.1 EVDD

External analog supply voltage.

3.2.2 DEVDD

External digital supply voltage.

3.2.3 AVDD

Regulated analog supply voltage (internally generated).

3.2.4 DVDD

Regulated digital supply voltage (internally generated).

3.2.5 DVSS

Digital ground.

3.2.6 AVSS

Analog ground.

3.2.7 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

also

provides

functions

of

various

special

features

of

the

ATmega256/128/64RFR2.

3.2.8 Port D (PD7...PD0)

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.

Port

D

also

provides

functions

of

various

special

features

of

the

ATmega256/128/64RFR2.

3.2.9 Port E (PE7...PE0)

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