UNO R3 Mega328P Development Board for arduino
Pin changes plus two I2C pins (SDA and SCL: next to the AREF pin, the Analog 4 and 5 copy, not the additional I2C interface), added two pins, the RESET next one is IOREF, allowing the expansion board to adapt to on-board voltage, this pin is just told to expand the board's current on-board voltage (such as UNO is 5V, the power supply pin can be seen as copy, does not provide the level pull-up), and the other is after inactive placeholder pins.
(20) more stable RESET circuit. RESET key position has changed, be moved close to the USB interface board corner, more convenient to press.
3 ATmega16U2 to replace a 8U2, this does not mean a 16K flash R3 to make your code run faster, this update for the USB interface chip, in theory, it allows the UNO can emulate USB the HID, such as the MIDI/ Joystick/Keyboard.
1pcs * KUONGSHUN UNO R3