Note:  No USB cable version.  This version can not compatible with OS system.     Features:  Open the original schematic design, free development software interface download, also allow your needs to be modified, easy and convenient to download the program.  Can simply use sensors, all kinds of electronic components connection (such as LED lights, buzzer, buttons and photosensitive resistance, etc.), make all sorts of interesting work.  Using high-speed microprocessor controller (ATMEGA328), development interface and environment are all very simple, easy to understand, very suitable for beginners to learn.     Description:  Digital I / O: 0 - 13;  Analog I / O: 0 - 5;  Support ISP download function;  Input voltage: DC 5V ~ 9V (No external power supply when connected to the computer);  Output voltage: DC 5V / 3.3V;  Using Atmega328 microprocessor controller.     How to use:  1. Download the IDE.  2. Download the USB chip driver.  3. Plug in UNO development board, the driver will be installed automatically.  4. Select the UNO from the die.  5. Select the COM port.  6. The best choice first, come with routine procedures, burn into it.     Package included:  5 x UNO R3 Development Board.