ATmega325P datasheet(19/364 Pages) ATMEL

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8023F–AVR–07/09

ATmega325P/3250P

AVR Memories

7.1

Overview

This section describes the different memories in the ATmega325P/3250P. The AVR architecture

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

the ATmega325P/3250P features an EEPROM Memory for data storage. All three memory

spaces are linear.

7.2

In-System Reprogrammable Flash Program Memory

The ATmega325P/3250P contains 32K bytes On-chip In-System Reprogrammable Flash mem-

ory for program storage. Since all AVR instructions are 16 or 32 bits wide, the Flash is organized

as 16K x 16. For software security, the Flash Program memory space is divided into two sec-

tions, Boot Program section and Application Program section.

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

ATmega325P/3250P Program Counter (PC) is 14 bits wide, thus addressing the 16K program

memory locations. The operation of Boot Program section and associated Boot Lock bits for

software protection are described in detail in ”Boot Loader Support – Read-While-Write Self-Pro-

gramming” on page 256. ”Memory Programming” on page 271 contains a detailed description

on Flash data serial downloading using the SPI pins or the JTAG interface.

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 16.

ATmega325P 데이터시트(PDF) 19 Page - ATMEL Corporation