RS485通信驱动：实现通过串口调试助手下发任意个字符，单片机接收到后在末尾添加“回车+换行”符后再送回，在调试助手上重 新显示出来-RS485 communication drivers: through serial debugging assistant made under any number of characters, after the microcontroller receives at the end add carriage return line feed+ s