Serial Port, Voltage : 3.3V (Esp8266) 5V (Arduino)

WiFi module is industrial-grade chips ESP8266, which is ESP-12E with metal shield, strong anti-interference ability. Shield is pin-compatible with Arduino Uno, Mega2560 and other control board. A voltage converter chip is used to deal with 3.3V (Esp8266) and 5V (Arduino). Dual DIP switches is used for serial ports so that this module shield can be used alone as an Arduino Uno expansion board, and also be used as ESP8266 expansion board. Serial data is transported to WiFi device transparently, and vice versa. Arduino program does not need any configuration. WebServer is developed to configure WiFi parameters and serial port parameters. The module shield can be used as an independent ESP8266 development board. for instance, downloading the official AT commands firmware, NodeMCU open source firmware can be used. The module shield also can be used as stand-alone expansion board for Arduino Uno.