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Cpu core, 1 architectural overview – Rainbow Electronics ATtiny10 User Manual

Page 6

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6

8127B–AVR–08/09

ATtiny4/5/9/10

4.

CPU Core

This section discusses the AVR core architecture in general. The main function of the CPU core
is to ensure correct program execution. The CPU must therefore be able to access memories,
perform calculations, control peripherals, and handle interrupts.

4.1

Architectural Overview

Figure 4-1.

Block Diagram of the AVR Architecture

In order to maximize performance and parallelism, the AVR uses a Harvard architecture – with
separate memories and buses for program and data. Instructions in the program memory are
executed with a single level pipelining. While one instruction is being executed, the next instruc-
tion is pre-fetched from the program memory. This concept enables instructions to be executed
in every clock cycle. The program memory is In-System Reprogrammable Flash memory.

The fast-access Register File contains 16 x 8-bit general purpose working registers with a single
clock cycle access time. This allows single-cycle Arithmetic Logic Unit (ALU) operation. In a typ-
ical ALU operation, two operands are output from the Register File, the operation is executed,
and the result is stored back in the Register File – in one clock cycle.

Flash

Program
Memory

Instruction

Register

Instruction

Decoder

Program

Counter

Control Lines

16 x 8

General

Purpose

Registrers

ALU

Status

and Control

I/O Lines

Data Bus 8-bit

Data

SRAM

Dir

ec

t A

ddr

essing

In

d

ir

e

ct

A

ddr

essing

Interrupt

Unit

Watchdog

Timer

Analog

Comparator

Timer/Counter 0

ADC