ATmega48PA/88PA/168PA/328P
7. 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 Flash 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.
16
8161D–AVR–10/09
ATMEL [ ATMEL ]
