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 ATmega48PA/88PA/168PA 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 (ATmega88PA and ATmega168PA).

The ATmega48PA/88PA/168PA 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 ATmega48PA 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 ATmega48PA

0x0000

0x7FF

Program Memory

Application Flash Section

ATmega48PA/88PA/168PA

AVR Memories

Datasheet Complete

DS40002011A-page 39