4
7674F–AVR–09/09
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), three flexible Timer/Counters with compare 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 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
timer base while the rest of the device is sleeping. The ADC Noise Reduction mode stops the
CPU and all I/O modules except Asynchronous Timer and ADC, to minimize 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 consump-
tion. 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 technology. The
On-chip ISP Flash allows the program memory to be reprogrammed in-system through an SPI
serial interface, by a conventional nonvolatile memory programmer, or by an On-chip Boot pro-
gram running on the AVR core. The boot program 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 Read-While-Write
operation. By combining an 8-bit RISC CPU with In-System Self-Programmable Flash on a
monolithic chip, the Atmel ATmega164P/324P/644P is a powerful microcontroller that provides a
highly flexible and cost effective solution 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.
Differences between ATmega164P and ATmega644P
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