An ATmega328 in DIP package, pre-loaded with the Arduino pro mini 8MHz Bootloader. This will allow you to use Arduino code in your custom embedded project without having to use an actual Arduino board.
To get this chip working with Arduino IDE, you do not require an external 16MHz crystal or resonator, all you need to supply is a 3.3V or 5V supply, and a serial connection. If you are not comfortable doing this, we recommend purchasing the Arduino Uno board that has all of these built into the board.
Atmel’s ATMega328 8-Bit Processor in 28 pin DIP package. It’s like the ATmega168, with double the flash space. 32K of program space. 23 I/O lines, 6 of which are channels for the 10-bit ADC. Runs up to 20MHz with external crystal. Package can be programmed in circuit. 1.8V to 5V operating voltage!
To compile and upload a sketch to this chip you just need to select 'Arduino Pro or Pro Mini (3.3V, 8MHz) w/ ATmega328' from the tools - board menu (don't worry about the 3.3V part, thats the minimum voltage, you can run these at 5V if you need to).
Note: This contains the bootloader used on the Arduino Pro Mini.