Datasheet

6
ATtiny4/5/9/10 [DATASHEET]
8127F–AVR–02/2013
4. CPU Core
This section discusses the AVR core architecture in general. The main function of the CPU core is to ensure cor-
rect 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 instruction 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 typical ALU operation, two oper-
ands 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
Direct Addressing
Indirect Addressing
Interrupt
Unit
Watchdog
Timer
Analog
Comparator
Timer/Counter 0
ADC