5
8023F–AVR–07/09
ATmega325P/3250P
The ATmega325P/3250P provides the following features: 32K bytes of In-System Programma-
ble Flash with Read-While-Write capabilities, 1K bytes EEPROM, 2K byte SRAM, 54/69 general
purpose I/O lines, 32 general purpose working registers, a JTAG interface for Boundary-scan,
On-chip Debugging support and programming, three flexible Timer/Counters with compare
modes, internal and external interrupts, a serial programmable USART, Universal Serial Inter-
face with Start Condition Detector, an 8-channel, 10-bit ADC, a programmable Watchdog Timer
with internal Oscillator, an SPI serial port, and five software selectable power saving modes. The
Idle mode stops the CPU while allowing the SRAM, Timer/Counters, SPI port, and interrupt sys-
tem 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, 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 consumption.
The device is manufactured using Atmel’s high density non-volatile memory technology. The
On-chip In-System re-Programmable (ISP) Flash allows the program memory to be repro-
grammed In-System through an SPI serial interface, by a conventional non-volatile memory
programmer, or by an On-chip Boot program running on the AVR core. The Boot program can
use any interface to download the application program in the Application Flash memory. Soft-
ware 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 ATmega325P/3250P is a powerful
microcontroller that provides a highly flexible and cost effective solution to many embedded con-
trol applications.
The ATmega325P/3250P AVR is supported with a full suite of program and system develop-
ment tools including: C Compilers, Macro Assemblers, Program Debugger/Simulators, In-Circuit
Emulators, and Evaluation kits.
2.2
Comparison between ATmega325P and ATmega3250P
The ATmega325P and ATmega3250P differs only in memory sizes, pin count and pinout.
Table2-1 on page 5 summarizes the different configurations for the four devices.
Table 2-1.
Configuration Summary
Device
Flash
EEPROM
RAM
General Purpose
I/O Pins
ATmega325P
32K bytes
1K bytes
2K bytes
54
ATmega3250P
32K bytes
1K bytes
2K bytes
69