# NodeMCU Documentation NodeMCU is an [eLua](http://www.eluaproject.net/) based firmware for the [ESP8266 WiFi SOC from Espressif](http://espressif.com/en/products/esp8266/). The firmware is based on the Espressif NON-OS SDK and uses a file system based on [spiffs](https://github.com/pellepl/spiffs). The code repository consists of 98.1% C-code that glues the thin Lua veneer to the SDK. The NodeMCU *firmware* is a companion project to the popular [NodeMCU dev kits](https://github.com/nodemcu/nodemcu-devkit-v1.0), ready-made open source development boards with ESP8266-12E chips. ## Programming Model The NodeMCU programming model is similar to that of [Node.js](https://en.wikipedia.org/wiki/Node.js), only in Lua. It is asynchronous and event-driven. Many functions, therefore, have parameters for callback functions. To give you an idea what a NodeMCU program looks like study the short snippets below. For more extensive examples have a look at the `/lua_examples` folder in the repository on GitHub. ```lua -- a simple HTTP server srv = net.createServer(net.TCP) srv:listen(80, function(conn) conn:on("receive", function(sck, payload) print(payload) sck:send("HTTP/1.0 200 OK\r\nContent-Type: text/html\r\n\r\n

Hello, NodeMCU.

") end) conn:on("sent", function(sck) sck:close() end) end) ``` ```lua -- connect to WiFi access point wifi.setmode(wifi.STATION) wifi.sta.config("SSID", "password") ``` ```lua -- register event callbacks for WiFi events wifi.sta.eventMonReg(wifi.STA_CONNECTING, function(previous_state) if(previous_state==wifi.STA_GOTIP) then print("Station lost connection with access point. Attempting to reconnect...") else print("STATION_CONNECTING") end end) ``` ```lua -- manipulate hardware like with Arduino pin = 1 gpio.mode(pin, gpio.OUTPUT) gpio.write(pin, gpio.HIGH) print(gpio.read(pin)) ``` ## Getting Started 1. [Build the firmeware](build.md) with the modules you need. 1. [Flash the firmware](flash.md) to the chip. 1. [Upload code](upload.md) to the firmware.