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))