本文主要介绍DA14681 UART ADAPTER的使用。利用SDK中提供的ADAPTER，可以方便地使用各种外设，如IIC、SPI、UART等。(This paper mainly introduces the use of DA14681 UART ADAPTER. The use of SDK provided in ADAPTER, you can easily use a variety of peripherals, such as IIC, SPI, UART and so on