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AVR

ATMEGA 8

MICRO-CONTROLLER

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INTRODUCTION ATmega8 is a 8-bit microcontroller based on

the AVR RISC architecture

By executing powerful instructions in a singleclock cycle, the ATmega8 achieves throughput

approaching 1 MIPS per MHz

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Contd....

In order to maximize performance and

parallelism, the AVR uses a Harvard

architecture- which separates memories and

buses for program and data

Instruction in program memory are executed

with single level pipelining

This concept enables instructions to beexecuted in every clock cycle

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FEATURES

High-performance 8 bit Microcontroller

Up to 16 MIPS Throughput at 16 MHz

32 x 8 General Purpose Working Registers Six ADC channels in PDIP package

Internal Calibrated Oscillator

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TYPES OF PACKAGES 28-pin PDIP (Plastic Dual In-line Package)

32-pin TQFP (Thin Quad film Package)

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MEMORYSEGMENTS 8K Bytes of Flash program memory

512 Bytes EEPROM (Electrically Erasable

Programmable Read Only Memory) 1K Byte Internal RAM (Random Access

Memory)

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Contd....

Write/Erase Cycles: 10,000 Flash/100,000

EEPROM

Data retention: 20 years at 85C/100 years at

25C

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PIN OUT

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PIN DESCRIPTION

VCC Digital supply voltage

GND Ground

RESET A low level on this pin for longer thanthe minimum pulse length will generate a

reset, even if the clock is not running

AREF The analog reference pin for the A/DConverter

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AVCC The supply voltage pin for the A/DConverter

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PORTS

Three ports i.e PortB, PortC, PortD

Three registers associated with every port

DDRx Data Direction Register

PINx Port input

PORTx- Port output

*Notex is subscript and could be either of B, C, D

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Port B (PB7..PB0)

Port B is an 8-bit bi-directional I/O port

Can be used either as a input port or as

output port ( direction must be specified in

programming)

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REGISTER DESCRIPTION OF I/O PORTS

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Port C (PC5..PC0)

Port C is an 7-bit bi-directional I/O port

Can be used either as a input port or as

output port ( direction must be specified in

programming)

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Port D (PD7..PD0)

Port D is an 8-bit bi-directional I/O port

Can be used either as a input port or as

output port ( direction must be specified in

coding)

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Contd....

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Contd....

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Contd....

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Thank you