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NodeMCU 2.2.0

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A Lua based firmware for ESP8266 WiFi SOC

NodeMCU is an eLua based firmware for the ESP8266 WiFi SOC from Espressif. The firmware is based on the Espressif NON-OS SDK 2.2.0 and uses a file system based on 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, ready-made open source development boards with ESP8266-12E chips.


  • Easy to program wireless node and/or access point
  • Based on Lua 5.1.4 (without debug, os modules)
  • Asynchronous event-driven programming model
  • more than 65 built-in modules
  • Firmware available with or without floating point support (integer-only uses less memory)
  • Up-to-date documentation at

Programming Model

The NodeMCU programming model is similar to that of 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.

-- a simple HTTP server
srv = net.createServer(net.TCP)
srv:listen(80, function(conn)
	conn:on("receive", function(sck, payload)
		sck:send("HTTP/1.0 200 OK\r\nContent-Type: text/html\r\n\r\n<h1> Hello, NodeMCU.</h1>")
	conn:on("sent", function(sck) sck:close() end)
-- connect to WiFi access point
wifi.sta.config{ssid="SSID", pwd="password"}


The entire NodeMCU documentation is maintained right in this repository at /docs. The fact that the API documentation is maintained in the same repository as the code that provides the API ensures consistency between the two. With every commit the documentation is rebuilt by Read the Docs and thus transformed from terse Markdown into a nicely browsable HTML site at


Due to the ever-growing number of modules available within NodeMCU, pre-built binaries are no longer made available. Use the automated custom firmware build service to get the specific firmware configuration you need, or consult the documentation for other options to build your own firmware.

This project uses two main branches, master and dev. dev is actively worked on and it's also where PRs should be created against. master thus can be considered "stable" even though there are no automated regression tests. The goal is to merge back to master roughly every 2 months. Depending on the current "heat" (issues, PRs) we accept changes to dev for 5-6 weeks and then hold back for 2-3 weeks before the next snap is completed.

A new tag is created every time dev is merged back to master. They are listed in the releases section here on GitHub. Tag names follow the <SDK-version>-master_yyyymmdd pattern.




MIT © zeroday/


lua based interactive firmware for mcu like esp8266




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