a tmega8 basics
TRANSCRIPT
AVR ATMEGA 8
MICRO-CONTROLLER
INTRODUCTION• ATmega8 is a 8-bit microcontroller based on
the AVR RISC architecture• By executing powerful instructions in a single
clock cycle, the ATmega8 achieves throughput approaching 1 MIPS per MHz
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• 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 be executed in every clock cycle
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
TYPES OF PACKAGES
• 28-pin PDIP (Plastic Dual In-line Package)• 32-pin TQFP (Thin Quad film Package)
MEMORY SEGMENTS• 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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• Write/Erase Cycles: 10,000 Flash/100,000 EEPROM
• Data retention: 20 years at 85°C/100 years at 25°C
PIN OUT
PIN DESCRIPTION• VCC Digital supply voltage• GND Ground• RESET A low level on this pin for longer than
the minimum pulse length will generate a reset, even if the clock is not running
• AREF The analog reference pin for the A/D Converter
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• AVCC The supply voltage pin for the A/D Converter
PORTS• Three ports i.e PortB, PortC, PortD• Three registers associated with every port DDRx – Data Direction Register PINx – Port input PORTx- Port output
*Note – ‘x’ is subscript and could be either of B, C, D
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)
REGISTER DESCRIPTION OF I/O PORTS
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)
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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Thank you…