一个函数专门向上位机发送数据，上位机接受 一个函数是通过上位机向单片机发送并回传显示 还有一个是串口调试工具 适合初学者入门(A function to send data to the upper computer, the upper computer to accept. A function is sent by the upper computer to the MCU and transmitted back and forth. Another is the se