RN8209参考，包括参考程序，用户手册，通讯参考等(RN8209 reference, including reference program, user manual, communication reference etc.)

RN8209初始化UART通讯参考程序,包含SPI示例程序和UART程序(RN8209 initializes the UART communication reference program, including the SPI sample program and the UART program.)