说明：  ESP8266 WiFi SoC offers a complete and self-contained Wi-Fi networking solution it can be used to host the application or to offload Wi-Fi networking functions another application processor. When ESP8266 hosts the application, it boots up directly an external flash. In has integrated cache to improve the performance of the system in such applications. Alternately, serving as a Wi-Fi adapter, wireless internet access can be added to any microcontroller-based design with simple connectivity through UART interface or the CPU AHB bridge interface.