nodemcu-firmware

# NodeMCU 3.0.0
> Lua-based firmware for ESP8266 WiFi SOC

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NodeMCU is an open source [Lua](https://www.lua.org/) based firmware for the [ESP8266 WiFi SOC from Espressif](https://www.espressif.com/en/products/socs/esp8266) and uses an on-module flash-based [SPIFFS](https://github.com/pellepl/spiffs) file system. NodeMCU is implemented in C and is layered on the [Espressif NON-OS SDK](https://github.com/espressif/ESP8266_NONOS_SDK).

The firmware was initially developed as is a companion project to the popular ESP8266-based [NodeMCU development modules]((https://github.com/nodemcu/nodemcu-devkit-v1.0)), but the project is now community-supported, and the firmware can now be run on _any_ ESP module.

**The NodeMCU `release` and `dev` branches target the ESP8266. The `dev-esp32` branch targets the ESP32.**

## Summary

- Easy to program wireless node and/or access point
- Based on Lua 5.1.4 or Lua 5.3 but without `debug`, `io`, `os` and (most of the) `math` modules
- Asynchronous event-driven programming model
- More than **70 built-in C modules** and **close to 20 Lua modules**
- Firmware available with or without floating point support (integer-only uses less memory)
- Up-to-date documentation at [https://nodemcu.readthedocs.io](https://nodemcu.readthedocs.io)

### LFS support

In July 2018 support for a Lua Flash Store (LFS) was introduced. LFS  allows Lua code and its associated constant data to be executed directly out of flash-memory; just as the firmware itself is executed. This now enables NodeMCU developers to create **Lua applications with up to 256Kb** Lua code and read-only constants executing out of flash. All of the RAM is available for read-write data!

## 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`](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<h1> Hello, NodeMCU.</h1>")