Datasheet

12. AVR Memories

12.1 Overview

This section describes the different memory types in the device. The AVR architecture has two main

memory spaces, the Data Memory and the Program Memory space. In addition, the device features an

EEPROM Memory for data storage. All memory spaces are linear and regular.

12.2 In-System Reprogrammable Flash Program Memory

The ATmega48A/88A/168A contains 4K/8K/16Kbytes 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 2K/4K/8K

x 16. For software security, the Flash Program memory space is divided into two sections - Boot Loader

Section and Application Program Section in the device (ATmega88A and ATmega168A).

The ATmega48A/88A/168A Program Counter (PC) is 11/12/13 bits wide, thus addressing the 2K/4K/8K

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

software protection are described in detail in Self-Programming for ATmega48A and Boot Loader Support

– Read-While-Write Self-Programming. Refer to Memory Programming for the description of Flash data

serial downloading using the SPI pins.

Constant tables can be allocated within the entire program memory address space, using the Load

Program Memory (LPM) instruction.

Timing diagrams for instruction fetch and execution are presented in Instruction Execution Timing.

Figure 12-1. Program Memory Map ATmega48A

0x0000

0x7FF

Program Memory

Application Flash Section

ATmega48A/88A/168A

AVR Memories

Datasheet Complete

DS40002007A-page 39