主要功能为，从USB总线读取延时参数，单片机延时发送内存缓冲区的一个字节数据到USB总线，每传送一个字节数据查询USB总线是否有停止USB总线通信命令，如有停止USB总线通信命令，则重新开始检查串口握手信号，开始下一次USB总线通信。

-Main function is to read from the USB bus delay parameters, single-chip delay sending a byte of data memory buffer to the USB bus, send a byte of data queries USB bus stop USB bus communication command, if any, to stop the USB the bus communication command, then re-start check the serial handshake signals to start the next USB bus communication.