5
8011KS–AVR–09/08
ATmega164P/324P/644P
The ATmega164P/324P/644P provides the following features: 16/32/64K bytes of In-System
Programmable Flash with Read-While-Write capabilities, 512B/1K/2K bytes EEPROM, 1/2/4K
bytes SRAM, 32 general purpose I/O lines, 32 general purpose working registers, Real Time
Counter (RTC), thr ee flexible Timer/Coun ters with co mpare modes and PWM, 2 USARTs, a byte
oriented 2-wire Serial Interface, a 8-channel, 10-bit ADC with optional differential input stage
with programmable gain , programmable Watchdog Timer with Internal Oscilla tor, 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/Coun ters, 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 timer base
while the rest of the device is sleeping. The ADC Noise Reduction mode stops the CPU and all
I/O modules excep t Asynchronous Timer and ADC, to m inimize switching noise during ADC
conversions. In Standby mode, the Crystal/Resonator Oscillator is running while the rest of the
device is sleeping. This allows very fast start-up combined with low power consumption. In
Extended Standby mode, both the main Oscillator and the Asynchronous Timer continue to run.
The device is manufactured using Atmel’s high-density nonvolatile memory techno logy. The On-
chip ISP Flash allows the program memory to be reprogrammed in-system through an SPI serial
interface, by a conventional nonvolatile memory programm er, or by an On-chip Boot program
running on the AVR core. The boot progra m can use any interface to download the application
program in the application Flash memory. Software in the Boot Flash section will continue to run
while the Application Flash section is updated, providing true Rea d-While-Write operation. By
combining an 8-bit RISC CPU with In-System Self-P rogrammable Flash on a monolithic chip,
the Atmel ATmega164P/324P/644P is a powerful microcontroller that provides a highly flexible
and cost effective solut ion to many embedded control applications.
The ATmega164P/324P/644P AVR is supported with a full suite of program and system devel-
opment tools including : C compilers, macro assemblers, program debugger/simulators, in-circuit
emulators, and evaluation kits.
2.2 Comparison Between ATmega164P, ATmega324P and ATmega644P
Table 2-1. Dif fe re nc es be tw ee n AT me g a1 64 P an d AT me g a6 44 P
Device Flash EEPROM RAM
ATmega164P 16 Kbyte 512 Bytes 1 Kbyte
ATmega324P 32 Kbyte 1 Kbyte 2 Kbyte
ATmega644P 64 Kbyte 2 Kbyte 4 Kbyte
