3
2467S–AVR–07/09
ATmega128
Block Diagram
Figure 2.
Block Diagram
PROGRAM
COUNTER
INTERNAL
OSCILLATOR
WATCHDOG
TIMER
STACK
POINTER
PROGRAM
FLASH
MCU CONTROL
REGISTER
SRAM
GENERAL
PURPOSE
REGISTERS
INSTRUCTION
REGISTER
TIMER/
COUNTERS
INSTRUCTION
DECODER
DATA DIR.
REG. PORTB
DATA DIR.
REG. PORTE
DATA DIR.
REG. PORTA
DATA DIR.
REG. PORTD
DATA REGISTER
PORTB
DATA REGISTER
PORTE
DATA REGISTER
PORTA
DATA REGISTER
PORTD
TIMING AND
CONTROL
OSCILLATOR
OSCILLATOR
INTERRUPT
UNIT
EEPROM
SPI
USART0
STATUS
REGISTER
Z
Y
X
ALU
PORTB DRIVERS
PORTE DRIVERS
PORTA DRIVERS
PORTF DRIVERS
PORTD DRIVERS
PORTC DRIVERS
PB0 - PB7
PE0 - PE7
PA0 - PA7
PF0 - PF7
RESET
VCC
AGND
GND
AREF
XT
AL1
XT
AL2
CONTROL
LINES
+
-
ANALOG
COMP
ARA
T
O
R
PC0 - PC7
8-BIT DATA BUS
AVCC
USART1
CALIB. OSC
DATA DIR.
REG. PORTC
DATA REGISTER
PORTC
ON-CHIP DEBUG
JTAG TAP
PROGRAMMING
LOGIC
PEN
BOUNDARY-
SCAN
DATA DIR.
REG. PORTF
DATA REGISTER
PORTF
ADC
PD0 - PD7
DATA DIR.
REG. PORTG
DATA REG.
PORTG
PORTG DRIVERS
PG0 - PG4
TWO-WIRE SERIAL
INTERFACE