NodeMCU program to read buttons and light up LEDs, communicates with MQTT

voting.lua

broker_ip_address='192.168.178.19'

wifi.sta.config({ssid="ssid",pwd="password"})
m = mqtt.Client('esp', 120, 'dev', 'dev')

wifi.setmode(wifi.STATION)

gpio.mode(1, gpio.INPUT, gpio.PULLUP)
gpio.mode(2, gpio.INPUT, gpio.PULLUP)
gpio.mode(3, gpio.OUTPUT, gpio.PULLUP)
gpio.mode(4, gpio.OUTPUT, gpio.PULLUP)

m:on("message", function(client, topic, data)
  print("got message: " .. topic)
  local _, _, led, state = string.find(topic, 'vote.led.([0123]).(%a+)')
  if state == 'on' then
     gpio.write(led + 3, 0)
  elseif state == 'off' then
     gpio.write(led + 3, 1)
  else
     print("message could not be parsed")
  end
end)

function connect_to_broker()
  m:connect(broker_ip_address,
            1883, 0,
            function(client)
               m:subscribe('vote/led/#', 0, function() print('subscribed to led messages') end)
            end,
            function(client)
               print('connection to message broker failed')
            end)
end

key_pins = { 1, 2, 5, 6 }
key_state = { 1, 1, 1, 1 }
keyboard_timer = tmr.create()
keyboard_timer:register(100, tmr.ALARM_AUTO, function ()
  for i, pin in ipairs(key_pins) do
      local new_state = gpio.read(pin)
      if new_state ~= key_state[i] then
         print("key " .. i .. " state " .. new_state)
         key_state[i] = new_state
         if new_state == 1 then
            m:publish("vote/keypress/" .. i, '', 0, 0)
         end
      end
  end
end)
keyboard_timer:start()

wait_led_state = 0
netup_timer = tmr.create()
netup_timer:register(150, tmr.ALARM_AUTO, function ()
  ip_address = wifi.sta.getip()
  if ip_address == nil then
    gpio.write(3, wait_led_state)
    wait_led_state = wait_led_state == 1 and 0 or 1
  else
    gpio.write(3, 1)
    netup_timer:stop()
    print("IP address: " .. ip_address)
    connect_to_broker()
  end
end)
netup_timer:start()