Datasheet

7701F–AVR–10/12

Atmel ATtiny24/44/84 [Preliminary]

6. Memories

This section describes the different memories in the Atmel

ATtiny24/44/84. The AVR

archi-

tecture has two main memory spaces, the data memory space and the program memory

space. In addition, the Atmel ATtiny24/44/84 features an EEPROM memory for data storage.

All three memory spaces are linear and regular.

6.1 In-System Re-programmable Flash Program Memory

The Atmel

ATtiny24/44/84 contains 2/4/8K bytes of on-chip, in-system, reprogrammable flash

memory for program storage. Since all AVR instructions are 16 or 32 bits wide, the flash mem-

ory is organized as 1024/2048/4096 x 16.

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

ATtiny24/44/84 program counter (PC) is 10/11/12 bits wide, thus addressing the

1024/2048/4096 program memory locations. “Memory Programming” on page 163 contains a

detailed description on Flash data serial downloading using the SPI pins.

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

Timing” on page 12.

Figure 6-1. Program Memory Map

6.2 SRAM Data Memory

Figure 6-2 on page 16 shows how the ATtiny24/44/84 SRAM Memory is organized.

The lower 160 data memory locations address the register file, the I/O memory, and the inter-

nal data SRAM. The first 32 locations address the register file, the next 64 locations the

standard I/O memory, and the last 128/256/512 locations address the internal data SRAM.

The five different addressing modes for the data memory are: 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 mode reaches the entire data space.

The indirect with displacement mode reaches 63 address locations starting from the base

address given by the Y- or Z-register.

0x0000

0x03FF/0x07FF/0xFFF

Program Memory