This Nano Mult-Function expansion board is designed specially for Arduino Nano, solve the problem of wiring confusing when a variety of sensors connected. Lead out all digital IO port and analog IO port, each one with standard positive and negative power interface. Lead out the I2C interface of mainboard for convenient connection. Increasing the DC power supply interface. Nano USB interface supply current is actually only 50MA, to bring high-current devices, such as the steering, is obviously insufficient. So in the DC power connector provide external power supply to ensure the stability of equipment operation.