NodeMCU error connecting to WiFi

问题

I have tried a blink on the NodeMCU working ok, but when doing basic connection to WiFi I get this error:

init.lua:4: attempt to concatenate global 'gw' (a nil value)

this is the connection

wifi.setmode(wifi.STATION)
wifi.sta.config("wifi-name","password") 
ip, nm, gw=wifi.sta.getip()
print("\nIP Info:\nIP Address: "..ip.." \nNetmask: "..nm.." \nGateway Addr: "..gw.."\n")

回答1:

With NodeMCU many functions are asynchronous (assume this to be the default). Hence, calling wifi.sta.config isn't blocking your main thread and consequently your device most likely isn't connected to WiFi by the time you invoke wifi.sta.getip.

If you have a firmware from the dev branch you can use the WiFi event monitor to fix that:

wifi.sta.eventMonReg(wifi.STA_GOTIP, function() 
  ip, nm, gw=wifi.sta.getip()
  print("\nIP Info:\nIP Address: "..ip.." \nNetmask: "..nm.." \nGateway Addr: "..gw.."\n")
end)

I documented a more basic timer-callback driven approach in a Gist:

wifiReady = 0

function configureWiFi()
    wifi.setmode(wifi.STATION)
    wifi.sta.config(WIFI_SSID, WIFI_PASS)
    wifi.sta.connect()
    tmr.alarm(WIFI_ALARM_ID, 1000, 1, wifi_watch)
end
-- while NOT connected to WiFi you blink a LED, see below
function wifi_watch()
    -- 0: STATION_IDLE,
    -- 1: STATION_CONNECTING,
    -- 2: STATION_WRONG_PASSWORD,
    -- 3: STATION_NO_AP_FOUND,
    -- 4: STATION_CONNECT_FAIL,
    -- 5: STATION_GOT_IP.
    status = wifi.sta.status()
    if status == 5 then
        -- only do something if the status actually changed
        -- you could of course combine these two 'if's but it's more explicit for this gist
        if wifiReady == 0 then
            wifiReady = 1
            print("WiFi: connected")
            turnWiFiLedOn()
            -- do something
        end
    else
        wifiReady = 0
        print("WiFi: (re-)connecting")
        turnWiFiLedOnOff()
        wifi.sta.connect()
    end
end

来源：https://stackoverflow.com/questions/37495036/nodemcu-error-connecting-to-wifi

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lua

nodemcu