ATmega88 datasheet(16/340 Pages) ATMEL

16 / 340 page

7530H–AVR–02/09

ATmega48/88/168 Automotive

Figure 5-2.

Program Memory Map, ATmega88 and ATmega168

5.2

SRAM Data Memory

Figure 5-3 shows how the ATmega48/88/168 SRAM Memory is organized.

The ATmega48/88/168 is a complex microcontroller with more peripheral units than can be sup-

ported within the 64 locations reserved in the Opcode for the IN and OUT instructions. For the

Extended I/O space from 0x60 - 0xFF in SRAM, only the ST/STS/STD and LD/LDS/LDD instruc-

tions can be used.

The lower 768/1280/1280 data memory locations address both the Register File, the I/O mem-

ory, Extended I/O memory, and the internal data SRAM. The first 32 locations address the

memory, and the next 512/1024/1024 locations address the internal data SRAM.

The five different addressing modes for the data memory cover: Direct, Indirect with Displace-

ment, Indirect, Indirect with Pre-decrement, and Indirect with Post-increment. In the Register

File, registers R26 to R31 feature the indirect addressing pointer registers.

The direct addressing reaches the entire data space.

The Indirect with Displacement mode reaches 63 address locations from the base address given

by the Y- or Z-register.

When using register indirect addressing modes with automatic pre-decrement and post-incre-

ment, the address registers X, Y, and Z are decremented or incremented.

The 32 general purpose working registers, 64 I/O Registers, 160 Extended I/O Registers, and

the 512/1024/1024 bytes of internal data SRAM in the ATmega48/88/168 are all accessible

through all these addressing modes. The Register File is described in “General Purpose Regis-

ter File” on page 10.

0x0000

0x0FFF/0x1FFF

Program Memory

Application Flash Section

Boot Flash Section

ATmega88 Datasheet(PDF) 16 Page - ATMEL Corporation