6

8025FS–AVR–08/08

ATmega48P/88P/168P/328P

architecture is more code efficient while achieving throughputs up to ten times faster than con-

ventional CISC microcontrollers.

The ATmega48P/88P/168P/328P provides the following features: 4K/8K/16K/32K bytes of In-

System Programmable Flash with Read-While-Write capabilities, 256/512/512/1K bytes

EEPROM, 512/1K/1K/2K bytes SRAM, 23 general purpose I/O lines, 32 general purpose work-

ing registers, three flexible Timer/Counters with compare modes, internal and external

interrupts, a serial programmable USART, a byte-oriented 2-wire Serial Interface, an SPI serial

port, a 6-channel 10-bit ADC (8 channels in TQFP and QFN/MLF packages), a programmable

Watchdog Timer with internal Oscillator, and five software selectable power saving modes. The

Idle mode stops the CPU while allowing the SRAM, Timer/Counters, USART, 2-wire Serial Inter-

face, 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 inter-

rupt 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 Reduc-

tion 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 ISP Flash allows the program memory to be reprogrammed In-System through an SPI

serial interface, by a conventional non-volatile 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 ATmega48P/88P/168P/328P is a powerful microcontroller that pro-

vides a highly flexible and cost effective solution to many embedded control applications.

The ATmega48P/88P/168P/328P AVR is supported with a full suite of program and system

development tools including: C Compilers, Macro Assemblers, Program Debugger/Simulators,

In-Circuit Emulators, and Evaluation kits.

2.2

Comparison Between ATmega48P, ATmega88P, ATmega168P, and ATmega328P

The ATmega48P, ATmega88P, ATmega168P, and ATmega328P differ only in memory sizes,

interrupt vector sizes for the three devices.

ATmega88P, ATmega168P, and ATmega328P support a real Read-While-Write Self-Program-

ming mechanism. There is a separate Boot Loader Section, and the SPM instruction can only

execute from there. In ATmega48P, there is no Read-While-Write support and no separate Boot

Loader Section. The SPM instruction can execute from the entire Flash.

Table 2-1.

Memory Size Summary

Device

Flash

EEPROM

RAM

Interrupt Vector Size

ATmega48P

4K Bytes

256 Bytes

512 Bytes

1 instruction word/vector

ATmega88P

8K Bytes

512 Bytes

1K Bytes

1 instruction word/vector

ATmega168P

16K Bytes

512 Bytes

1K Bytes

2 instruction words/vector

ATmega328P

32K Bytes

1K Bytes

2K Bytes

2 instructions words/vector