2. Overview
The ATmega64A is a low-power CMOS 8-bit microcontroller based on the AVR enhanced RISC architecture. By
executing powerful instructions in a single clock cycle, the ATmega64A achieves throughputs approaching 1 MIPS
per MHz, allowing the system designer to optimize power consumption versus processing speed.
2.1
Block Diagram
Figure 2-1. Block Diagram
PF0 - PF7
PA0 - PA7
PC0 - PC7
VCC
GND
PORTA DRIVERS
PORTF DRIVERS
PORTC DRIVERS
AVCC
DATA REGISTER
PORTF
DATA DIR.
REG. PORTF
DATA REGISTER
PORTA
DATA DIR.
REG. PORTA
DATA REGISTER
PORTC
DATA DIR.
REG. PORTC
8-BIT DATA BUS
XTAL1
XTAL2
AREF
CALIB. OSC
INTERNAL
OSCILLATOR
ADC
OSCILLATOR
OSCILLATOR
PROGRAM
COUNTER
STACK
POINTER
WATCHDOG
TIMER
JTAG TAP
TIMING AND
CONTROL
PROGRAM
FLASH
MCU CONTROL
REGISTER
SRAM
ON-CHIP DEBUG
RESET
BOUNDARY-
SCAN
INSTRUCTION
REGISTER
TIMER/
COUNTERS
GENERAL
PURPOSE
REGISTERS
X
Y
Z
PROGRAMMING
LOGIC
INSTRUCTION
DECODER
INTERRUPT
UNIT
PEN
CONTROL
LINES
ALU
EEPROM
STATUS
REGISTER
2-WIRE SERIAL
INTERFACE
SPI
USART0
USART1
DATA REGISTER
PORTE
DATA DIR.
REG. PORTE
DATA REGISTER
PORTB
DATA DIR.
REG. PORTB
DATA REGISTER
PORTD
DATA DIR.
REG. PORTD
DATA REG. DATA DIR.
PORTG
REG. PORTG
PORTB DRIVERS
PORTD DRIVERS
PORTG DRIVERS
PORTE DRIVERS
PE0 - PE7
PB0 - PB7
PD0 - PD7
PG0 - PG4
The AVR core combines a rich instruction set with 32 general purpose working registers. All the 32 registers are
directly connected to the Arithmetic Logic Unit (ALU), allowing two independent registers to be accessed in one
single instruction executed in one clock cycle. The resulting architecture is more code efficient while achieving
throughputs up to ten times faster than conventional CISC microcontrollers.
The ATmega64A provides the following features: 64 Kbytes In-System Programmable Flash with Read-While-
Write capabilities, 2 Kbytes EEPROM, 4 Kbytes SRAM, 53 general purpose I/O lines, 32 general purpose working
registers, Real Time Counter (RTC), four flexible Timer/Counters with compare modes and PWM, two USARTs, a
byte oriented Two-wire Serial Interface, an 8-channel, 10-bit ADC with optional differential input stage with pro-
grammable gain, programmable Watchdog Timer with internal Oscillator, an SPI serial port, IEEE std. 1149.1
ATmega64A [DATASHEET]
3
8160DS–AVR–02/2013
ATMEL [ ATMEL ]
