This ATmega328P microcontroller UNO R3 development board is very easy to use.
Add two I2C pins next to the AREF pin(SDA and SCL, just copy of Analog 4 and 5).
Add two pins next to RESET, one is IOREF which allows the board to adapt onboard voltage.
More stable RESET circuit; the RESET is moved to place closer to USB interface, more convenient to press.
ATmega328P replaces 8U2 so that UNO can simulate USB HID, e.g MIDI/Joystick/Keyboard.

Technical Details

Size (LWH): 6 inches, 6 inches, 5 inches
Product Details
Product Dimensions: 6 x 6 x 5 inches
Shipping Weight: 0.3 pounds (View shipping rates and policies)
ASIN : B00ZP6TZQO