ATmegaXX4 Datasheet, Pinout, Minimal Circuit, Maximum Frequency Calculator

The ATmegaXX4 family of AVR devices includes the ATmega164, ATmega324, ATmega644, and the ATmega1284. They share a common I/O system, having 2 8-bit timers, and 1 16-bit, with the exception of the ATmega1284, which has an additional 16-bit timer. They differ in the amount of memory available, with flash memory size ranging from 16kB to 128kB. They could be considered upgrades from the older ATmega16 and ATmega32 parts, since they have the same basic pinout but more functionality.

The most popular members of this family are the ATmega644 and the ATmega1284. The others are much less common, partly because of the electronics "pop culture", which has chosen the ATmega644 to be the big brother of the Arduino's ATmega328. If you just need I/O, and not a lot of memory, it may be worthwhile to check into the ATmega164 and ATmega324, although there is a lot to say for standardizing on the ATmega644. For lower power (lower Vcc) there is the ATmegaXX4PV-10PU, with a Vcc down to 1.8V. All versions of the ATmegaXX4P run at up to 20MHz with the exception of the ATmegaXX4PV versions, which run at a maximum of 10MHz.

Power Supply vs. Maximum Frequency

The calculator below provides a way to find the maximum operating frequency for any valid power supply voltage (2.7 to 5.5). Enter the power supply voltage and click "Calculate Max Frequency" to find the ATmegaxx4's specified maximum clock speed at your Vcc.

Maximum Frequency Calculator for ATmega164, ATmega324, ATmega644, ATmega1284

ATmega164, ATmega324, ATmega644, ATmega1284 Features
Flash 16k32k64k128k
EEPROM 0.5k1k2k4k
RAM 1k2k4k16k
I/O Pins 32
Interrupts 3135
ADC Channels 8
RT Counter (w/osc)1
Timers (8-bit) 2
Timers (16-bit) 12
PWM (8-bit) 4
PWM (16-bit) 2
Price (1's) $5.73$7.33$8.38$8.32
Power Consumption (approximate) 1.125mA/MHz
Maximum I/O Current (per pin) 40mA
Maximum I/O Current (all ports) 100mA(low)/150mA(high)
Maximum I/O Current (total) 200mA (PDIP)
Maximum I/O Current (total)400mA (PDIP/QFP/MLF)

ATmega164, ATmega324, ATmega644, ATmega1284 Datasheet

Link to ATmega164, ATmega324, ATmega644, ATmega1284 datasheet from Atmel's website.

ATmega164, ATmega324, ATmega644, ATmega1284 Pinout

ATmega644PA-PU pinout ATmega644PA-AU pinout

ATmega164, ATmega324, ATmega644, ATmega1284 "Minimal" Circuit Diagram

The circuit below shows a programming port, reset circuit, and a crystal oscillator. Any or all of these could be left off and the device would function perfectly well. By default the unit runs from the 1MHz internal RC oscillator.

ATmega644 minimal schematic diagram