ATmega328 microcontroller with Arduino Uno Bootloader
The ATmega328 with a pre-loaded Arduino Uno bootloader is great for your more customised designs where you'd like to add Arduino Uno code without buying the Uno board. To enable the bootloader to function exactly like an Uno board you will need a 16 MHz crystal oscillator or resonator, a 5 V power supply and a serial connection.
Features & Benefits of the Uno Bootloader 32 K program space 23 I/O lines Runs up to 20 MHz 1.8 V to 5 V operating voltage