ESP8266, NodeMCU GPIOs, ESP-12 modules ,ESP-12 pins, ESP8266 datasheet, Main functions for GPIO in the Arduino IDE, Introduction When the subject is ESP8266, it is normal that our attention is on the Wifi module. We've already discussed some applications in previous articles, and there's still a lot of cool stuff to see in the future. We've looked at how the ESP8266 communicates with the world via wifi, and now ....