Arduino UNO R3 compatible microcontroller development board with CH340G USB-TTL bridge. Our UNO R3 board comes with the essential features of the original Arduino UNO R3, with some additional advantages. With the included pin header and the special advanced board layout, is our UNO R3 board much better suitable for your breadboard projects than any other UNO R3 board design, the original Arduino UNO R3 included (see picture). Essential features of the Original Arduino UNO R3, not included in many of the Chinese boards: – Diode “VD” avoids conflicts between different power supplies when connected to 2 different Vin sources same time – Transistor “Q1” protects your computer’s USB port when UNO is connected to “Vin” source the same time – ML358 OPA decouples the LED on I/O13 to make the port usable for other purposes as well Additional features as advantage over the original Arduino UNO R3: – 3.3V LDO “U5” can deliver 200mA contiunously (original Arduino UNO R3 only 150mA) – additional tie points 3.3V, 5V, GND, SCL, and SDA for easier I2C bus access – precisely 16MHz crystal with 0.003% error (original Arduino UNO R3 only +/- 0.5%) For clock applications, the original Arduino UNO R3 board is not suitable because of its very bad clock generator: – A clock, built with the original Arduino UNO R3, would have an error of about 7 minutes per day!! – A clock, built with our UNO R3 board, would have an error of less than 3 seconds per day!! Windows 10 and most Linux distributions come with the necessary driver for the CH340G USB already on board. Drivers for older Windows versions and Mac OS can be downloaded fro our website. A set of FREE headers, to use the UNO on a breadboard, is included with every UNO controller.