3

ATmega8(L)

2486QS–AVR–10/06

Overview

The ATmega8 is a low-power CMOS 8-bit microcontroller based on the AVR RISC

architecture. By executing powerful instructions in a single clock cycle, the ATmega8

achieves throughputs approaching 1 MIPS per MHz, allowing the system designer to

optimize power consumption versus processing speed.

Block Diagram

Figure 1. Block Diagram

INTERNAL

OSCILLATOR

OSCILLATOR

WATCHDOG

TIMER

MCU CTRL.

& TIMING

OSCILLATOR

TIMERS/

COUNTERS

INTERRUPT

UNIT

STACK

POINTER

EEPROM

SRAM

STATUS

REGISTER

USART

PROGRAM

COUNTER

PROGRAM

FLASH

INSTRUCTION

REGISTER

INSTRUCTION

DECODER

PROGRAMMING

LOGIC

SPI

ADC

INTERFACE

COMP.

INTERFACE

PORTC DRIVERS/BUFFERS

PORTC DIGITAL INTERFACE

GENERAL

PURPOSE

REGISTERS

X

Y

Z

ALU

+

-

PORTB DRIVERS/BUFFERS

PORTB DIGITAL INTERFACE

PORTD DIGITAL INTERFACE

PORTD DRIVERS/BUFFERS

XTAL1

XTAL2

CONTROL

LINES

VCC

GND

MUX &

ADC

AGND

AREF

PC0 - PC6

PB0 - PB7

PD0 - PD7

AVR CPU

TWI

RESET