Few examples to play with NodeMCU

Connect to the wireless network

print(wifi.sta.getip())
--nil
wifi.setmode(wifi.STATION)
wifi.sta.config("SSID","password")
print(wifi.sta.getip())
--192.168.18.110

Arduino like IO access

pin = 1
gpio.mode(pin,gpio.OUTPUT)
gpio.write(pin,gpio.HIGH)
gpio.mode(pin,gpio.INPUT)
print(gpio.read(pin))

HTTP Client

-- A simple http client
conn=net.createConnection(net.TCP, false)
conn:on("receive", function(conn, pl) print(pl) end)
conn:connect(80,"121.41.33.127")
conn:send("GET / HTTP/1.1\r\nHost: www.nodemcu.com\r\n"
    .."Connection: keep-alive\r\nAccept: */*\r\n\r\n")

HTTP Server

-- a simple http server 
srv=net.createServer(net.TCP) 
srv:listen(80,function(conn) 
 conn:on("receive",function(conn,payload) print(payload) 
 conn:send("<h1> Hello, NodeMcu.</h1>")
 end) 
end)

PWM

function led(r,g,b)
    pwm.setduty(1,r)
    pwm.setduty(2,g)
    pwm.setduty(3,b)
end
pwm.setup(1,500,512)
pwm.setup(2,500,512)
pwm.setup(3,500,512)
pwm.start(1)
pwm.start(2)
pwm.start(3)
led(512,0,0) -- red
led(0,0,512) -- blue

Blinking Led

lighton=0
tmr.alarm(0,1000,1,function()
if lighton==0 then
    lighton=1
    led(512,512,512)
    -- 512/1024, 50% duty cycle
else
    lighton=0
    led(0,0,0)
end
end)

Bootstrap

--init.lua will be excuted
file.open("init.lua","w")
file.writeline([[print("Hello World!")]])
file.close()
node.restart()  -- this will restart the module.

Use timer to repeat

tmr.alarm(1,5000,1,function() print("alarm 1") end)
tmr.alarm(0,1000,1,function() print("alarm 0") end)
tmr.alarm(2,2000,1,function() print("alarm 2") end)
-- after sometime
tmr.stop(0)

A pure lua telnet server

-- a simple telnet server
s=net.createServer(net.TCP,180)
s:listen(2323,function(c)
    function s_output(str)
      if(c~=nil)
        then c:send(str)
      end
    end
    node.output(s_output, 0)   
    -- re-direct output to function s_ouput.
    c:on("receive",function(c,l)
      node.input(l)           
      --like pcall(loadstring(l)), support multiple separate lines
    end)
    c:on("disconnection",function(c)
      node.output(nil)        
      --unregist redirect output function, output goes to serial
    end)
    print("Welcome to NodeMcu world.")
end)

Interfacing with sensor

-- read temperature with DS18B20
t=require("ds18b20")
t.setup(9)
addrs=t.addrs()
-- Total DS18B20 numbers, assume it is 2
print(table.getn(addrs))
-- The first DS18B20
print(t.read(addrs[1],t.C))
print(t.read(addrs[1],t.F))
print(t.read(addrs[1],t.K))
-- The second DS18B20
print(t.read(addrs[2],t.C))
print(t.read(addrs[2],t.F))
print(t.read(addrs[2],t.K))
-- Just read
print(t.read())
-- Just read as centigrade
print(t.read(nil,t.C))
-- Don't forget to release it after use
t = nil
ds18b20 = nil
package.loaded["ds18b20"]=nil

Please note that these examples were taken from the official website of NodeMCU