2. 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
3. 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 be
executed in every clock cycle
4. 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
5. TYPES OF PACKAGES
• 28-pin PDIP (Plastic Dual In-line Package)
• 32-pin TQFP (Thin Quad film Package)
6. MEMORY SEGMENTS
• 8K Bytes of Flash program memory
• 512 Bytes EEPROM (Electrically Erasable
Programmable Read Only Memory)
• 1K Byte Internal RAM (Random Access
Memory)
9. 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
11. 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
12. 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)
15. 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)
16. 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)
