Adafruit 2010 PCB design board Adafruit Pro Trinket - 3V 12MHz AVR® ATmega ATMega328

The Pro Trinket PCB measures only 1.5" x 0.7" x 0.2" (without headers) but packs the same capability as an Arduino UNO. So it's great once you've finished up a prototype on an official Arduino UNO and want to make the project smaller. It has onboard USB bootloading support using a MicroUSB jack. With Optiboot support, you can either program your Pro Trinket over USB or with a FTDI cable. The Pro Trinket 3V uses the Atmega328P chip, which is the same core chip in the Arduino UNO, Duemilanove and Mini. However, it uses 3V logic and 12MHz clock which means it's good when you want a lower-power and lower-voltage setup. Pro Trinket is programmable using the Arduino IDE as you already set up, and almost all Arduino projects will work out of the box!