1、Open original design of the circuit diagram, the development software interface is easy to download, you can also modify it according to your needs, the download procedure is simple and convenient. 2、You can simply use sensors, a variety of electronic components (such as: LED lights, buzzers, buttons, photoresistors, etc.) to make a variety of interesting works. 3、Using the high-speed microprocessor controller, the development interface and environment are very simple and easy to understand, which is very suitable for beginners to learn. 4、Pin change, two I2C pins are added next to the AREF pin (SDA and SCL, only copy of Analog4 and 5, not an extra I2C interface). In addition, two pins are added next to RESET, one is IOREF. The expansion board can be adapted to the onboard voltage. This pin only tells the expansion board what the current onboard voltage is, and the other is the placeholder pin that will be used later. 5、The more stable RESET circuit, the position of the RESET button has also changed, and it has been moved to the corner of the board near the USB interface, which is more convenient to press. 6、Replaces 8U2, which does not mean that R3 with 16K flash can make your code run faster. This update is for USB interface chip. Item Type: Development Board Digital I/O: Digital input/output terminals total 0~13 Analog I/O: The analog input/output terminals are 0~5 Download Function: Support ISP download function Input Voltage: No external power supply is required when connecting to the computer USB, external power supply 7V~12V DC voltage input Output Voltage: 5V DC voltage output and 3.3V DC voltage output Controller:  microprocessor controller 1 x Development Board