Datasheet

ATmega164A/PA/324A/PA/644A/PA/1284/P
 2018 Microchip Technology Inc. Data Sheet Complete DS40002070A-page 14
2.1 Block diagram
Figure 2-1. Block diagram
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 ATmega164A/164PA/324A/324PA/644A/644PA/1284/1284P provide the following features:
16/32/64/128Kbytes of In-System Programmable Flash with Read-While-Write capabilities, 512/1K/2K/4Kbytes
EEPROM, 1/2/4/16Kbytes SRAM, 32 general purpose I/O lines, 32 general purpose working registers, Real
Time Counter (RTC), three (four for ATmega1284/1284P) flexible Timer/Counters with compare modes and
PWM, 2 USARTs, a byte oriented two-wire Serial Interface, a 8-channel, 10-bit ADC with optional differential
input stage with programmable gain, programmable Watchdog Timer with Internal Oscillator, an SPI serial port,
IEEE std. 1149.1 compliant JTAG test interface, also used for accessing the On-chip Debug system and
programming and six software selectable power saving modes. The Idle mode stops the CPU while allowing the
SRAM, Timer/Counters, SPI port, and interrupt system to continue functioning. The Power-down mode saves
the register contents but freezes the Oscillator, disabling all other chip functions until the next interrupt or
Hardware Reset. In Power-save mode, the asynchronous timer continues to run, allowing the user to maintain a
CPU
GND
VCC
RESET
Power
Supervision
POR / BOD &
RESET
Watchdog
Oscillator
Watchdog
Timer
Oscillator
Circuits /
Clock
Generation
XTAL1
XTAL2
PORT A (8)
PORT D (8)
PD7..0
PORT C (8)
PC5..0
TWI
SPI
EEPROM
JTAG/OCD
16bit T/C 1
8bit T/C 2
8bit T/C 0
SRAMFLASH
USART 0
Internal
Bandgap reference
Analog
Comparator
A/D
Converter
PA7..0
PORT B (8)
PB7..0
USART 1
TOSC1/PC6TOSC2/PC7
16bit T/C 1
16bit T/C 3*
* Only available in ATmega1284/1284P