The UNO R3 differs from all preceding boards inthat it does not use the FTDI USB-to-serial driver chip. Instead, it featuresthe Atmega16U2 (Atmega8U2 up to version R2) programmed as a USB-to-serialconverter
Name ： SpecificationController ： ATMEGA16-U2
Flash Memory: 32 KB (ATmega328) of which 0.5 KB used by bootloader
SRAM: 2 KB
EEPROM: 1 KB
Input Voltage (recommended) ：7-12V
Operating voltage ： 5V
Input Voltage (limits) ： 6-20V
DC Current per I/O Pin ： 40 mA
DC Current for 3.3V Pin ： 50 mA
Digital IO pins ：14 (of which 6 provide PWM output)
Analog input pins： 6
USB Port ： typeB USB
Clock Speed : 16MHz
Noted
We produce this board based on the open-source arduino official schematics.The printing or color on the board may be different from each production date, but the function is exactly the same.

• Updated Version -Stitching changes: beside the AREF sutural added two I2C pins (SDA and SCL, only Analog copy of 4 and 5, are not additional I2C interface), in addition, beside the RESET also added two pins, one is IOREF, can let the extension board to board, load voltage, the stitching is tell extension board currently on-board voltage is how many (such as UNO is 5 v, can is regarded as a copy of the power pins, does not provide a level), the other one is after treated with placeholder pins.
• Updated version-The RESET circuit is more stable. RESET button position is changed, and moved to near the USB interface of voids, it is more convenient.
• Updated version-ATmega16U2 instead of 8 u2, this does not mean that there are 16 k flash R3 can make your code run faster, the update service for the USB interface chip, it make UNO can simulate USB HID in theory, such as MIDI / Joystick / Keyboard.
• 1 x Compatible Arduino UNO R3 Development Board 1 x USB OTG Cable 1xbag
• E-book of fun arduino projects

Updated Version -Stitching changes: beside the AREF sutural added two I2C pins (SDA and SCL, only Analog copy of 4 and 5, are not additional I2C interface), in addition, beside the RESET also added two pins, one is IOREF, can let the extension board to board, load voltage, the stitching is tell extension board currently on-board voltage is how many (such as UNO is 5 v, can is regarded as a copy of the power pins, does not provide a level), the other one is after treated with placeholder pins.Virocana