NodeMCU is based on widely explored esp8266 System on Chip and are widely used for Internet of Things (IoT) projects. It uses LUA based programming language.We can also do Arduino programming for NodeMCU.
First of all CAUTION ! for arduino users.
* The ESP8266 chip requires 3.3V power supply voltage. It should not be powered with 5 volts like other arduino boards.
* NodeMCU ESP-12E dev board can be connected to 5Vusing micro USB connector or Vin pin available on board.
* The I/O pins of ESP8266 communicate or input/output max 3.3V only. i.e. the pins are NOT 5V tolerant inputs.
Installing Arduino Core for NodeMCU
Version 1.6.4 onwards Arduino allows installation of third-party platform packages using Boards Manager.
Start Arduino and open Preferences window(File>Preferences).
Enter http://arduino.esp8266.com/stable/package_esp8266com_index.json into Additional Board Manager URLs field.
Open Boards Manager from Tools > Board menu and install esp8266 platform.
After installation select your ESP8266 board from Tools > Board menu as shown.