nodemcu-firmware/docs/en/index.md

NodeMCU Documentation

NodeMCU is an open source Lua based firmware for the ESP8266 WiFi SOC from Espressif and uses an on-module flash-based SPIFFS file system. NodeMCU is implemented in C and is layered on the Espressif NON-OS SDK.

The firmware was initially developed as is a companion project to the popular ESP8266-based NodeMCU development modules, but the project is now community-supported, and the firmware can now be run on any ESP module.

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)
		print(payload)
		sck:send("HTTP/1.0 200 OK\r\nContent-Type: text/html\r\n\r\n<h1> Hello, NodeMCU.</h1>")
	end)
	conn:on("sent", function(sck) sck:close() end)
end)

-- connect to WiFi access point
wifi.setmode(wifi.STATION)
wifi.sta.config("SSID", "password")

-- 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)

-- manipulate hardware like with Arduino
pin = 1
gpio.mode(pin, gpio.OUTPUT)
gpio.write(pin, gpio.HIGH)
print(gpio.read(pin))

Lua Flash Store (LFS)

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!

Getting Started

1. Build the firmware with the modules you need.
2. Flash the firmware to the chip.
3. Upload code to the firmware.