DROK UNO R3 Board ATmega328P Atmega16u2 Development Board with USB Cable for Arduino - Compatible With Arduino UNO R3 Mega 2560 Nano Robot 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.