Datasheet
3
ATmega8A [DATASHEET]
8159E–AVR–02/2013
2. Overview
The Atmel
®
AVR
®
ATmega8A is a low-power CMOS 8-bit microcontroller based on the AVR RISC architecture. By
executing powerful instructions in a single clock cycle, the ATmega8A achieves throughputs approaching 1 MIPS
per MHz, allowing the system designer to optimize power consumption versus processing speed.
2.1 Block Diagram
Figure 2-1. 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