Hello! MCU chip pins are the interfaces on the chip used to connect external components. They can be divided into input pins and output pins. The input pin receives an external signal or data and sends it inside the chip for processing. The output pin transmits data or signals from the chip to the outside. Each pin has a specific function and purpose in the chip design, such as IO port, clock pin, power pin, etc. Pin numbers are usually indicated as numbers or letters, and the chip manufacturer provides a pin function sheet for reference. Choosing the right pin connection is critical to the proper functioning of the MCU. Hope this basic information can help you!