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7/29/2019 ATmega8 Basics
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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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Contd....
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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Contd....
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Thank you