ATmega328P datasheet(16/448 Pages) ATMEL

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8161D–AVR–10/09

ATmega48PA/88PA/168PA/328P

AVR Memories

7.1

Overview

This section describes the different memories in the ATmega48PA/88PA/168PA/328P. The AVR

architecture has two main memory spaces, the Data Memory and the Program Memory space.

In addition, the ATmega48PA/88PA/168PA/328P features an EEPROM Memory for data stor-

age. All three memory spaces are linear and regular.

7.2

In-System Reprogrammable Flash Program Memory

The ATmega48PA/88PA/168PA/328P contains 4/8/16/32K bytes On-chip In-System Repro-

grammable Flash memory for program storage. Since all AVR instructions are 16 or 32 bits

wide, the Flash is organized as 2/4/8/16K x 16. For software security, the Flash Program mem-

ory space is divided into two sections, Boot Loader Section and Application Program Section in

ATmega88PA and ATmega168PA. See SELFPRGEN description in section ”SPMCSR – Store

Program Memory Control and Status Register” on page 292 for more details.

The F lash memory has an endurance of at least 10,000 write/erase cycles. The

ATmega48PA/88PA/168PA/328P Program Counter (PC) is 11/12/13/14 bits wide, thus address-

ing the 2/4/8/16K program memory locations. The operation of Boot Program section and

associated Boot Lock bits for software protection are described in detail in ”Self-Programming

the Flash, ATmega48PA” on page 269 and ”Boot Loader Support – Read-While-Write Self-Pro-

gramming, ATmega88PA, ATmega168PA and ATmega328P” on page 277. ”Memory

Programming” on page 294 contains a detailed description on Flash Programming in SPI- or

Parallel Programming mode.

Constant tables can be allocated within the entire program memory address space (see the LPM

– Load Program Memory instruction description).

Timing diagrams for instruction fetch and execution are presented in ”Instruction Execution Tim-

ing” on page 13.

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