ATmega644PA datasheet(19/468 Pages) ATMEL

19 / 468 page

8152G–AVR–11/09

ATmega164PA/324PA/644PA/1284P

AVR Memories

7.1

Overview

This section describes the different memories in the ATmega164PA/324PA/644PA/1284P. The

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

space. In addition, the ATmega164PA/324PA/644PA/1284P features an EEPROM Memory for

data storage. All three memory spaces are linear and regular.

7.2

In-System Reprogrammable Flash Program Memory

The ATmega164PA/324PA/644PA/1284P contains 16/32/64/128K bytes On-chip In-System

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

bits wide, the Flash is organized as 32/64 x 16. For software security, the Flash Program mem-

ory space is divided into two sections, Boot Program section and Application Program section.

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

ATmega164PA/324PA/644PA/1284P Program Counter (PC) is 15/16 bits wide, thus addressing

the 32/64K program memory locations. The operation of Boot Program section and associated

Boot Lock bits for software protection are described in detail in ”Memory Programming” on page

296. ”Memory Programming” on page 296 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 15.

ATmega644PA датащи(PDF) 19 Page - ATMEL Corporation